Hand Made Bicycle Building

Las Vegas - Capital of the Dada Anti-life

noreply@blogger.com (Rick Guggemos) — Wed, 23 Sep 2009 02:05:00 +0000

Well… Here I sit waiting for my first seminar of my first Interbike. This, btw, is related to a new entrepreneurial venture that I’m trying to kick off for 2010 – not frame-building. Stay tuned here to be among those who first find out about it.

A rain delay in Dallas meant I got to my room at 2:30AM (my time). In Vegas, the dispatcher for the ground-transport company was convinced thought that being contrary and contradictory was really funny for weary travelers. Then, the registration desk at the hotel was very backed up – after all time of day hasn’t much meaning in Vegas. Finally I made the mistake of thinking that Vegas was only 1 hour ahead of Chicago – meaning I got up earlier than necessary.

The hotel is the Imperial Palace. The best aspect of these digs is that they reinforce my sense of entrepreneurial spirit (in other words its cheap). It’s rated 3 stars, the middle of the Vegas range. I’d hate to see the lower rated venues. Seriously, I’ve been in Motel 6s that seemed nicer. But, at the rates I got – it’s probably a fair value.

Having criticized the hotel, I should point to the objectionable elements. While my floor appears to be no-smoking, the ventilation system recycles the smells of tobacco smoke and air freshener. Not cool for anyone with sinus/allergy issue. Also, the room is old. How old? The shower still uses separate hot and cold faucets – one of which fits loosely enough that water sprays behind it and the fiberglass surround. Also, the shower and sink drains don’t – at least not beyond a trickle. The balconette faces a roof and two walls of windows – it’s almost impossible to see sky (fair enough that this is due to pricing). The cost of food is astronomical. I understand that the whole $2 buffet thing is long gone from Vegas, but $10 for a cafeteria croissant and small cupa is just a bit high. Especially in a place where one has traverse a floor of crazy, smoking gamblers to get in and out. Not my idea of the place for a vacation.

Being a newbie to Vegas, I am amazed that it exceeds any image I had of this town. In fact, I assumed that much of its reputation was a caricature – but that simply isn’t so. You’re welcome to laugh at me for being so naive, but there it is.

Yep, the characters in the hotel are pure Vegas. There are lots of bored looking people playing penny slots without really paying attention to their machine, or the people around them. It’s almost as if they’re catatonic. There were a few obvious prostitutes in the mix, some looking for action while others appear to be on their way home. I don’t know if they’re legal of not – but it feels strange to see them in a regular hotel.

On the other hand, the sun was shining (naturally) and it was 90 degrees this morning. I didn’t head to the Outdoor Demo Days: this morning was dedicated to journalists – and I wanted to attend seminars in the afternoon.

Instead it was time to get some fresh air (really important after the casino/hotel) and enjoy the dry heat. Walking past the Venetian (walking is probably a lower class thing to do in Vegas), the neighborhood looks nice and upper class. But I was hailed by a hooker, who wouldn’t give up after just one try. At 8:30AM Vega time. It was weird.

Coming back in the afternoon, there was a fellow selling "new Sony & Apple laptops" out of his shopping bags on the sidewalk in front of the Pallatzo and across the street from Dior. Down near Harrah's, someone was hawking CDs from a bag. Further down, there was a little gauntlet of people doing a rhythmic thing of slapping tickets on there wrist (making a slapping sound) and then thrusting them out in front of the pedestrians. At the last moment, they'd retract their arms if the walker wasn't a taker - starting the slapping cycle over. Based on their t-shirts, it looks like they were marketing a strip show. Again, weird.

More on tires and wheels and such

noreply@blogger.com (Rick Guggemos) — Sun, 20 Sep 2009 15:27:00 +0000

Today I finally got out on the updated carbon bike. The core of the ride was 32.63 miles in 1:57:32 - or a bit over 16.8 mph, with a total ride of 42 miles. That's pretty good for me, riding solo, on a breezy day. And the route was as hilly as its possible to find around here (although this isn't very hilly).

Initial impressions of the SRAM group. All parts worked correctly. The brakes do have enough modulation for my taste, along with good stopping power. The shifters shift reliably, as do the derailers (Force has replaced the Campy front derailer). The chain and cassette don't seem loud, although they are a bit louder than Campy when cross chained.

The grip around the base of the levers felt good; my initial impression was that it was better than Campy (due in part to its greater width). The end of the hoods have a larger and more pronounce hump than Campy. I like to ride with my palm on the hump with Campy, but all the weight is concentrated on the tall nub with the SRAM shifters. Overall, I was having more Ulnar nerve issues today than usual - but I'll need more rides to determine if this is related to SRAM shifters, or something else. Going forward, I may put on a longer stem to compensate for not riding on the shifter nub.

Overall, I'd say that the tires lived up to expectations - but I have to qualify it for now because the wheels are also new. The tubeless ride is definitely smoother riding - with this being most obvious on sharp-edged bumps. Its not quite like a high-quality tubular, but it's clearly a step up from an open tubular.

One other observation re the tires: They are very nicely concentric on the rims. Recently, I was using some Michelin Pro3Race on test wheels while building the rear-wheel fairing on a tri bike. It was almost scary how far from concentric these (expensive) tires are - so much so that I took them off and remounted them just to make sure that the beads were seated properly. Of course, when testing for clearances, this makes a great worst case example. But while riding, concentric tires roll more smoothly with less rolling resistance. So, again, I am impressed with the concentricity of the Hutchinson tubeless tires (based on a sample of 2).

While my time today was good, I suspect that it had more to do with my current conditioning and a need to burn off psychic energy. I'm sure, at least for now, that the wheels weren't really doing their job.

There is a nice downhill run where I test my rollout. My usual wheels are either an older pair of Campy Zonda (with the steel spokes rather than aluminum), or some MA3's laced up to Record hubs. With these wheels, no one out-rolls me, and I pass up many folks going down this hill.

The Easton EA70s were clearly not competitive going down this hill. I don't know whether this is seal drag, drag in the rachet of the freehub, or a bearing issue. Note that these wheels didn't even have a mile on them when I started this morning - and less than seven miles when I reached the coasting hill. Its entirely possible that the issue is just one of breaking in the bearing seals. Subjectively, the wheels felt as if they were rolling better towards the end of the ride. Guess I'll have post further on this issue after I get a few hundred miles on these wheels.

Over all, I enjoyed this mornings ride. With the gears working correctly, I could better enjoy the ride and the handling of my frame and fork. This really is a nice frame, and handles beautifully. Today was a super morning to enjoy it. It was still a little dark when I started and about 54 degrees. By the time I got home it was 65 degrees, sunny with blue sky.

And that's a wrap for today.

Old & New

noreply@blogger.com (Rick Guggemos) — Fri, 18 Sep 2009 22:57:00 +0000

Spent yesterday working in the shop. Busy day. Finished it by updating my personal carbon ride. It's been equipped with Record 10s w/ a long cage rear derailer. Of late, it's not shifting right. The cassette is fine, the chain is new, and the derailer tab checks out as straight. So... looks like the derailer is bent. I tried straightening the cage a bit, but there are so few flat surfaces on it that I couldn't get a good read on the alignment table.

Meanwhile, I've been meaning to test out some Hutchinson tubeless clinchers. Supposedly, with Stan's tape and fluid, they work well on Easton rims. And I happened to have a spare set of EA-70s lying around (don't know quite why). The wheels, however, are set up for a Shimano cassette - so a no go-on my Campy bikes.

However, I also have a bit of spare SRAM gear lying around including some 1st gen Rival shifters and rear derailer. Which, of course, would work with Easton rims.

So, I did the only bike-geek respectable thing possible: I've converted the old bike to SRAM.

For now, I can only offer initial thoughts - I don't have any meaningful mileage on this setup. But, here's what I have.

1) Stan's tape was easy to apply - using my truing stand. Without a stand, I think it would have been a pain because the tape is really made for a wider (MTB) rim. It requires tension and a wiggling motion to get it seated properly down below the bead.

2) Unlike with regular tubes, the threaded nut on the valve stem is necessary. Without it, the stem doesn't pull in tightly enough to prevent leakage. Using the nut cranks the stem down nicely.

3) Stan's instructions are right on, but the video is the way to learn the proper install method.

4) It takes tire levers to mount the Hutchinsons (at least on the EA70 rims). I understand the concern about tires blowing off (or at least of having tires loosen enough to loose air), hence the use of a carbon fiber bead that won't stretch. But I have to wonder if the Stan's tape is contributing to this issue. I'm going to have to try tubeless on a set of Ksyriums where rim tape isn't necessary.

5) The tires pumped right up with a floor pump, even without the water and soap suds seal at the rim. After inflating them, I put them in the sink to work in the suds (see Stan's video for explanation). Actually, I couldn't pump the tires up until the valve stems were tight. But, once this was done, the tire beads seemed leak-free. BTW, the next morning, the tires still felt full when squeezed.

6) Installing the fluid wasn't too hard, but because the applicator looks like a big syringe, I thought to draw in fluid and then squirt into the valve stem. Doesn't work that way - too big a nozzle, too thin a fluid: it all spills out. So, I used the applicator more as a funnel - connecting it to the stem - and pouring fluid into it.

7) The initial test rides seemed very plush, but I need to go back and check pressures and try again with some actual miles. Also, I need to get out the tire gauge and see how long the tires hold pressure.

8) The old style (silver) Rival shifters have a nice looking finish. I don't know if its painted or polished and anodized, or? But it looks nice. It will be interesting to see how durable it is. These shifters don't have all the adjustments available on newer SRAM shifters, but seem to fit my hands just fine.

9) For now, I'm using a Campy front derailer. This isn't working well - I can't seem to dial in the shifting. Next stop, Rival front shifter.

10) The rear is shifting nicely. It's so nice to have every cog available to me again. Too bad I didn't have a cassette with a 26t or 27t available. Now I just have to train myself in SRAM shifting. Let's acknowledge here that these 1st gen, lower level, shifters don't sound or feel as nice as Campy. But they are much cheaper and seem to be shifting great with the Rival derailer.

11) The brakes are 1st generation Force. Again, attractively finished. Good braking power - still checking out modulation. Fit of the Q/R impedes easy access to adjust the brake shoe on the cable side - but not outrageously so. These brakes don't have the centering screw of later versions - a loss, but not a major one. The rear brake feels more spongy than I'd like, may have to reduce the toe-in.

12) I haven't weighed anything, but suspect that the SRAM components are lighter or equal in weight to the Campy ones that were swapped out.

13) The cassette has an attractive looking spider inside of the cogs. Otherwise, the cassette just works - nothing to write home about.

14) The ratchet in the rear freehub seems rather draggy. It's not noisy, and the issue may just be too much grease. I'll have to wait and find out if these wheels roll ok, or not. If the hubs roll, then its a great bargain of a wheel set - complete with nice (low drag) stainless spokes. But if the hubs are friction factories, I'm not going to be very happy with these wheels. Perhaps I'll have to check out the Easton website regarding how to adjust the bearings.

That's all for now. I'll provide some more feedback once I have some miles on this combo.

If bikes had a memory...

noreply@blogger.com (Rick Guggemos) — Tue, 15 Sep 2009 18:39:00 +0000

oh the stories they could tell. Today continued our outstanding weather - it feels like San Diego or something. With the day job starting late on Tuesdays, I scooted out for a quick ride on what is now called the Death Bike, which has some stories of its own.

Death Bike is a track bike, originally designed for one of our local racers. He, however, found a good deal on a used BH carbon frame and canceled right after the tubes were mitered. What the heck, the frame was only a little small for me, and I didn't have much time on a pure track bike design, so the build moved forward as my bike. Naturally, its set up as a fixed gear, but not like the path racer. The wheels are clincher, with 23mm open tubs from Deda - nice rolling tires. It has track forks with thick walled blades and limited rake making them stiff stiff stiff. The rest of the frame isn't much different being of 2 x oversize tubing (a 35mm steel downtube is a serious piece of pipe) - which combined with its black paint presents a very serious look.

Death Bike has relatively long trail given its steep head tube, because of the short fork rake. At slower speeds, trail quickly begins to stabilize the bike, but the steep head tube and short wheel base allow it to turn quickly and in a small space. Frankly, I think the geo is nailed for track riding. But it is a bit jarring on the streets, and there isn't room for cushier tires.

Death Bike had an old Campy mid-level (Athena?) brake on the front to keep me safe on the road. Yep, I drill the fork crown. But recently, a friend borrowed it to see if he liked fixed gear riding. For this, I swapped in a SRAM Force brake. That puppy offers right . . . NOW! stopping power - ideal for someone not used to only one brake. To simplify the brake change, I swapped in a new bar with a Cane Creek lever (leaving the old brake and bar connected to each other).

Anyhow, my rider has lots of time on fixed-gear training cycles, so I guessed he could make the step up to a fixed gear bike pretty easily. Whoops, I was wrong. Should have been there to give him pointers. Anyhow, he quickly got launched, twice, and decided fixed was not for him. Hence the name Death Bike.

The new handlebar is a Nitto Rando. I don't have much experience with these, so I was pleased to find that the shape was more comfortable than I expected. The Rando has a great bend behind the brake lever which supports the hand without leaning on the lever. This makes it ideal for a bike with only one brake lever, as both hands get support.

Today's ride pointed out that this is really a pretty stiff handlebar. Some folks take think of flex as a bad thing, but a softer bar offers more comfort than a stiff one. My ulnar nerve sometimes gives me trouble, making my hands/fingers numb. There are many factors related to this, but for me the primary ones are: fitness; & stiffness of the the bike's front end. At this point in the season, most bikes don't bother my ulnar: my weight is going into the pedals, not the bars. But, even on a short 1.5 hr ride, I experienced numb hands with the Rando on the Death Bike. Don't get me wrong, many other bars would do the same thing. But don't buy the Rando expecting it to enhance your bike's ride.

Both the roads & trails had light traffic this morning. Blue sky and temperatures in the mid-70's made for ideal conditions. I beat out a pretty good pace: both the frame and the wheels like to scoot. Meanwhile, my mind was liberated from serious thoughts. When I chose to consider it, I could tell that I was breathing hard and pushing the pace. But mostly, I just didn't notice. Other than the Ulnar thing, I could gone for hours at this level. Sort of a Zen thing - my mind and body all doing its thing in a very coordinated fashion, but without conscious thought driving any of it. I don't know if this makes sense to you, but its a cool thing when it happens.

That's it for today. Enjoy your rides. Pix of something soon.

Good Weather

noreply@blogger.com (Rick Guggemos) — Mon, 14 Sep 2009 14:17:00 +0000

Lots of work yesterday, but the weather was too nice to miss riding. I went out on the path racer (yeah I need to post some pix) this afternoon. It's always a peaceful bike to ride - even when pushed.

Along the way, some guy comes blasting out into the street, without looking, from a pedestrian path connecting to a residential neighborhood. He's all tricked out on his C'dale six/sixteen - and practically glowing with reflective bits from head to toe (despite it being a bright sunny afternoon).

A quick swerve avoids him, but the expected pass from behind never arrives. Half mile down is a stop for a busy road, and before I get across Mr. C'dale shows up. No problem, I'm just beginning to cross - but I get the feeling that he's right behind me and trying to pass. It's not a good spot for this as we are entering a trail with center barrier and a speed bump (both of which seem useless). So I keep my tempo up and the sound of him recedes as the path gets bumpy.

After a sharp turn onto another trail, and a street crossing, the trail scoots down a viaduct under the expressway, then it's back up and half a mile to the first street crossing. As I'm waiting to cross, guess who shows up and manages to time things perfectly to cross without stopping. All of which is cool, he ought to be making better time than me anyway.

But, once he's in front, he slows down. I'm not out for a race, but I like to maintain my cadence, and I can't just shift gears to adjust to his. The nice weather has brought out lots of slow riders, so passing is a bit chancy in many sections. Eventually the opportunity comes, and I'm off.

The next crossing has a stop light, and you can guess what happens. Instead of waiting for the light, I go ahead and time the traffic to shoot across before he can react. This time I up my tempo for a bit, build a gap and settle in. After a mile and a half he makes another dumb pass in heavy traffic. Naturally, as soon as we're in the clear, he slows down. So one more time I pass him, and stick to my cadence. It's a few more miles to the next crossing. While there's plenty of traffic, no one is trying dumb passes here. Cool, I get to relax and just enjoy peddling, with the subtle speed control that comes with a fixed (don't worry, I have front and rear brakes).

Before the next street, there are a couple of sharp corners. Ahead of them, I come upon a couple riding single file, a bit slowly. Judging distances, I can probably get around them before the corners, but it will be close enough that they might be scared, or pissed off. So I slow, and follow them through. And they slow more. As do I. And then they slow down even more. And so do I, again. Five-hundred feet begin to feel like a life sentence - but I'm staying cool.

Naturally, as we emerge from the trees, and try turn into the crossing, Mr. C-dale comes flying through, with total disregard for where each of us is, or where we are heading.

This time, I get to feeling pissy. Traffic holds us up from a quick crossing. At the gap, I take off but this time I spin it up and hold the up-tempo for a couple of miles. The sun is shining and the sky is clear and a bright blue. This portion of the trail rarely has much traffic, and is true to form today. While often less than 100 yards from the expressway, the path rises, dips, and winds through woods and past ponds. Its some of the best local scenery - it reminds me of Minnesota. Three miles of kicking it gets me to my 18 mile marker, and the beginning of loop around to start home. A few trails come together here, and with the expectation of traffic, I slow down.

Naturally I'm waiting for my shadow to jump out - but he doesn't. The last stretch must have finished him off. I return to my normal tempo. Fat tires (32mm), at 75psi, run quietly and absorb most of the bumps. The ride is mellow now. The light has a fall-like quality, even though all of nature is still green. The miles disappear without thought. The effort remains, but its natural - not something to notice.

People must be heading home, because I don't use either my voice or my bell for the rest of the way. Out on the roads, even the drivers seem to have chilled out. The air tempurature is in the upper seventies - its real short-sleeve weather. The three stop lights I pass are in sync with my ride- and the bike just spins on through.

Somehow, the messages are muted where I'm normally reminded that it's good to be almost home. And I spin along. Its fun to feel how happy the tires are when I do silly sharp turns. The garage door is up when arriving at my drive, and I coast right in. Opening the door to the house, I smell the first batch of chili for the season. It's a bit early, but smells great. The kids both have friends over, and are out back releasing there extra energy. I grab a shower no longer caring about missing today's Century. Instead, I'm ready to go back to work.

Little Details make a custom frame

noreply@blogger.com (Rick Guggemos) — Fri, 17 Jul 2009 01:40:00 +0000

One of my current projects is a fast bike for someone who may yet try his hand at racing. I've been working with him to adjust his fit for some time now; and we're starting to see results. He's getting pretty quick on the bike, and can use much more handlebar drop than when we first started. That said, there's no way to get past the fact that he has an extreme body geometry where he needs about a 55CM seat-tube combined with 53CM top tube. And that's using a 9CM stem. You could say he's long in the leg.

He's a strong and heavy rider, so no wimpy frames for him. And it's going to be lugged steel. Now this presents some interesting issues. Generally, lug sets aren't available in multiple angles. So, framebuilders have to 'adjust' lugs to fit their designs.

For this frame, I've chosen Dazza's Slant Six (aka XL Compact) lugs with a Kirk Pacenti lugged Bottom Bracket. This combo is designed for use with a 2X Oversize tube set (in this case it'll be Columbus Life), with diameters as follows: DT=34.9mm, ST=31.8mm, TT=31.8mm. These fat tubes should keep everything plenty stiff. The Spirit chainstays will do their part to, running full size (i.e. without a taper) until the last 90mm. Most chainstays taper over the last 250-300mm - so this is a meaningful difference.

The Slant Six lugs create a frame with a modest slope (6 degrees) to the top tube, allowing for somewhat more standover clearance. Which is great. They are sized for a 1-1/8" steering tube - unlike most lugs which are sized for 1" steerers. Personally, I don't think that steerer diameter is very important for road bikes - but the rider wants a carbon fork and the larger steerer will leave us with more options.

So, back to the lugs, short top tube, and adjustments. The angles on the stock lower head tube lug, and on the BB between the seat and down tube, are about 3-1/2 degrees away from the plan on BikeCad. This means that it's time to adjust, in a fairly significant way.

I have some nice bending bars and quickly got the BB in shape. Naturally, the bent lug ports needs some hammering to make sure that they conformed to the shape of the tubes. The lower head tube lug is a bit more difficult. It is somewhat like a bikini lug, in that there isn't much lug on the headtube, especially above the down tube. This means that its hard to clamp this part of the lug in place during the bending, and that this section doesn't have enough material to both fill the gap created by the bend and provide a good surface area on the head tube. That's where this piece comes in. I traced the top of the lug onto a cutoff piece of head tube, and then cut it out.

This will get brazed into the corresponding section (see the second photo) of the lug, using brass filler. After some file work, it will fill the gap between the adjusted lug and the head tube. Some more filing on the outside of the lug will restore the outer shape (so that the shoreline of the lug doesn't become twice as thick).

The actual joint will be brazed with silver filler, hence it won't heat up enough to weaken the brass filler used to modify the lug. Cool concept but plenty of work.

That's it for this post. Cheers,b

They said what?

noreply@blogger.com (Rick Guggemos) — Wed, 08 Jul 2009 02:25:00 +0000

Its become clear to me that I shouldn't promise anything here - something always comes up to distract the dialog. So no promises, I think.

There many topics worthy of discussion, but what got me going tonight was this bit in Velo News

Now, I don't know about you, but I think big companies try to patent too much - especially broad concepts which they haven't invented or substantially developed. I think that Trek's 'Kamm Tail' fits this description. First of all, they are borrowing aerodynamic licks that have been employed repeatedly, for many years, and in a borad variety contexts - it's nothing new. And applying them to a bicycle isn't nothing new.

In fact, I've been experimenting with similar tubing shapes on TT bikes for over a year. And I didn't get the idea from Trek or anyone else in the bike business. In fact, I've long wondered why the so-called aerodynamicsts of the bike industry weren't exploring these ideas all along - thus making me wonder how many of them really know anything about aerodynamics.

It should be noted that an 8:1 aspect ratio is not optimal (as described in the article) for head-on air pressue. 8:1 represents a 12.5% ratio, which is near the maximum for the size of airfoil created by a bicycle tube, and the speeds at which a bike travels. Airfoils have scaling issues, and the smaller the airfoil is, the greater the challenges presented. If we want to talk about an optimal aspect ratio for dead-ahead air pressure, then we should be looking to something in the 8-10% range, meaning somewhere between 10:1 and 12:1. These are significantly different form an 8:1 ratio.

Of course, it's not just aspect ratio, but also the shape and size of the object which determines how slippery the object is. A really big object with a very slippery shape and aspect ratio may have more drag than a smaller object which has a sticky shape and aspect ratio. Or it may not. So much more needs to be pinned down, apart from the 8:1 ratio. But lets explore this further.

First, a round tube isn't much better than a square tube regarding the drag produced as an air stream hits it. Historically, metal aero-tubes had a round front and tapered rear. The rear fairing did little to improve aerodynamics over a normal round tube (although it never stopped a manufacturer from touting aero advantages). The simple learning here is that the leading edge (front) of the tube is the most critical shape for achieving low aero drag.

Trek suggests that the tube's profile should/can be cut off just past its broadest point. So let's look at this with their 8:1 profile and the UCI limit of 3:1 size.

Usually the thickest part of a wing is about 1/3 back from the leading edge. On an 8:1 ratio tube, with a 1" thickness, the chord (front to back distance) would be 8". If we took only the front 1/3 of that shape, the actual (as opposed to effective) chord would be reduced to 2-2/3". This creates a tube with a 1:2-2/3 aspect ratio. Which keeps us in the game vis a vis UCI rules. So far, so good.

Now lets talk about the Kamm Tail. The concept of the Kamm Tail (or more correctly Kamm Back) is that an aerodynamic automobile not only has too little aerodynamic downforce for stability, but actually can achieve aerodynamic lift as speed. The Kamm Back creates a low pressure area behind the vehicle (drag) which helps to maintain directional stability. So, while it works in conjunction with aerodynamic drag reduction, it actually is using drag to keep a car traveling in the correct direction. Which is quite different from what Trek is describing.

This doesn't make Trek's shapes or concept wrong, but shows how marketing mis-uses technology to explain and sell products.

OK, so let's get back to this shape thing. It looks like Trek has 1/3 of an inch left according to UCI rules. Should they max out the 3:1 ratio?

Aerodynamics occur in 3 dimensions. Any aerodynamicist who forgets this is unlikely to be successful for long. For example, a round down tube has a salami slice like shape (sort of an oval) as it presents itself to the wind - because the tube isn't vertical.

Moreover, the airflow will chase the lowest pressure areas. As with a swept wing on a jet, this means that on the downtube, there will be airflow from the further forward points (near the head tube) towards the bottom bracket - all else being equal. Perhaps you've seen an airplane with tiplets on the ends of the wing - they often look like small rudders. On the wing, air travels similarly down its length. Air below the wing has higher pressure than on top - so when the flow of air reaches the end of the wing, the high pressure below wants to flip over the top and fill the low-pressure area. This reduces lift and causes drag. The tiplet is designed to interfere with the spill of high pressure are from the bottom to the top, thus improving lift and reducing drag.

The sides of the downtube are symmetrical. So, if the wind is from dead-ahead, then there won't be a high and low pressure side. Nonetheless, all else being equal, the air flow along the downtube will be slightly downhill - which further elongates the oval presented to the wind.

It's possible that a tube that has a actual 3:1 ratio, presents itself to the wind at some other ratio - for example, instead of being 3" deep aerodynamically, it might be 4" long. Now this is of no particular advantage to one builder or another - they will all have a chance to leverage this phenomena. But it does prepare us for the next step.

Unlike what Trek says, the optimal cutoff for the airfoil is not at its widest point. The airflow needs to be stablized into a path similar to that it would take if the rear of the foil had not been truncated. The path from the thickes part of a wing to it's trailing edge is not a straight path. But it is generally the straightest part of the outline of the airfoil. Let's say that when we truncate an airfoil, we still need 10% of the overall chord length to be located behind the widest point of the airfoil. In reality, how much wing is required behind the maximum thickness is a function of the wing size, shape, and airspeed - so we're speaking in hypotheticals here when we use the numbe 10%.

Given that the base airfoil is 8:1 (per Trek), the 10% extra would be 0.8". Now, measured using the actual tube profile, we have a chord lenght of 2.667". Adding 0.8" to this gives us a chord of 3.467" - or an aspect ratio of almost 3.5:1 - well above the UCI limits. But let's think this over again. Assuming that we present a foil to the wind that is 4" deep and 1" wide, for a tube that has an actual 3:1 profile: In this case we have more of the aerodynamic airfoil with which to play. Let's move the widest point of the tube forward, so that it is 2.667" behind the leading edge when measured along the path of air flow. That means that we have 1.333" left behind the widest point, and this 1.333" is 13% of the original air foils chord. If we only needed 10% of the overall chord behind the widest point, then we have another 3% to play with.

Let me point out that the numbers above are not meant to emulate the reality of Trek's tube shape. Rather, they give the reader some insight into the sorts of opportunities and tradeoffs which exist in designing a an efficiently shaped downtube.

Now, if we have 3% of the chord left to play with, what should we do with this? If the wind always came from the front, we would probably just use it to truncate the shape closer to the trailing edge. However, the wind rarely is truely from directly ahead. All the points of the compass have equal likelyhood has being the source of any wind, and while the bike's ground movement adds another vector necessary to calculate effective (as opposed to true) wind direction, it should be obvious that we will commonly contend with a wind that is not from dead ahead. Further componding things this challenge is the fact that a bike rarely travels in a truely straight line. Instead bike and rider are constantly adjusting inputs, causing the front end to continually move back and forth.

So what? Think of our truncated airfoil. With wind dead ahead, a sharp corner at the rear has little impact. But, turn the wind direction 15 degrees to one side, and now this corner becomes a drag riser. We want to smooth the transition of the air flowing around this edge. A rounder shape will work better in these circumstances. So, the extra 3/10" in chord length might be best used to transition air around the rear of the tube, when its coming from a direction other than straight ahead.

With the widest part of the tube being located 2.667" from the leading edge, along the actual airflow, where is it located in a 90 degree cross section of the tube? Well, its 2.667/4.0 from the front. Solving the math gives us a maximum width 2" from the front of the tube. Similarly, the end of the rearward taper is located 2.600" inches back, leaving 0.4" that can be shaped to help cross winds get around the rear of the tube. All of this has been down in the context of UCI 3:1 rule.

Naturally, this isn't the end of the story. For example, cross winds see an assymetric shape, even though the tube is symmetric from left to right. This begs the question regarding whether there might be benefits to having a tube which is symmetric from front to back? Also, there are aerodynamic tools which can manange how well the airflow follows the contour of the airfoil. Remember when we (arbitrarily) suggested that the tube shape needed to include 10% of the overall (8") chord located behind the widest point of our tube? Flow managing tools could reduce this number without limiting our drag reduction. If so, then we would have more chord length available (within UCI rules) by which to manage how cross winds wrap around the down tube. And, what if there is another place where we can truncate the chord of the tube without compromizing aerodynamics? There is such a place, but that's a story for a different day.

Be aware, Trek is sloppy in describing what they are doing, greeding in suggesting that they may patent their technology, most likely accurate in describing what they doing as an improvement, and not producing an impact that you can measure within margins of error in real practice. Yeah, we haven't touched on this yet, but you the rider are the source aero drag. Yes the bike contributes, but its contribution is small. Your position on the bike; what accessories (water bottle(s), computer, tool bag, etc.) and how carry them; these are the important aspects of aerodynamics. Until you have these nailed, don't worry about the shape of your frame tubes, or how well hidden your brake may be.

Until next time, Cheers!

Rick

Cable Runs

noreply@blogger.com (Rick Guggemos) — Sun, 23 Nov 2008 17:30:00 +0000

Something that new framebuilders should learn sooner rather than later is that planning and installing small bits (cable guides, brake mounts, H2O mounts, etc.) are better done up front rather than after the frame is built.

This is doubly true with carbon fiber frames where small bits present some special challenges. I don't like to put lots of holes through my tubing, and I like to keep the holes as small as possible. The biggest challenge comes when a rider requests internal cable runs.

Routing of internal gear cables is dependent on the crank axle design. Some, like cartridge BBs, are hard to fit a cable around while staying within the BB. For these, I exit the cable at the base of the down tube and use a normal BB cable guide.

Where more space is available, however, its possible to do some interesting things. There are still some challenges however.

Many external cup BB's use a sleeve running around the axle and between the two cups. This isn't compatible with having shift cables inside the BB's. I've developed a split seal for inside the BB, where each bearing cup is sealed separately from the other - leaving a nice smooth axle around which the cable can turn on its run.

This opens up some neat possibilities. A large hole in the front of the BB allows the cable to run inside the down tube and directly into the BB. Then a whole at the rear of the BB has a cable tube running part way down the chain stay where it exits. The cable continues to a pre-formed housing stop - and through the housing to the rear derailer. This makes a very tidy looking setup.

For guides, I like 0.125" O.D. brass tube. This is easy to handle and requires a minimal hole through the tubing and chain stay.

Here are some pix of the chain stay tubing exit that I'm working on. To begin, I build up a filet around the tube as it exits the chainstay.

The filet is basically a thickened epoxy which: 1) doesn't run while curing; 2) has better compression strength than plain epoxy. As you can see from the picture, its hard to get a smooth filet - it's too sticky.

The first thing we have to do is drill out the end of the tunnel and make sure that the cable passes freely through it.

Then we borrow some techniques from steel frame building. Out comes the file, and I file the filet into a smooth shape. It seems to be looking pretty good here, so now we can reinforce this area.

Frankly, this is probably not necessary, but this bike is being built to last and the chain stay encounters pretty significant forces on a regular basis.

In this case, I'm going to put on two longitudinal plys of uni-CF. Each will be split in the middle, along its length, for about half its length. One will be laid from each direction, splitting around the exit hole. The splits allow me to better flatten the CF down, where I want it. These plys will wrap about 2/3 of the way down each side of the stay.

Next comes a uni-CF ply running directly around the stay (at 90 degrees to the prior stays). This ply won't be split, so our exit hole will be covered. Not to worry, it's easy to see where the hole is under the CF.

Finally, I'm putting a full wrap of my double layer 2x2 12K twill. This has a toughening layer between the two plys of CF, making it good for reinforcing a chain stay. The total reinforcement is 5 layers of 150 Gr/SqMeter CF - 3 uni, 2 low-crimp. When it's cured we'll need to drill out the exit hole and make sure all is smooth. Then this guid will be done. A similar arrangement will be used for the front derailer, but we can't finish it yet for reasons that will be obvious later.

Meanwhile, we need to squeeze our CF layers together, and remove the excess epoxy. This is a complicated area to work with. The part is small enough to easily fit in a vacuum bag. Given the small diameter of the chain stay, holding the plys together with good alignment, along with peel ply and bleeder felt, is a bit of a challenge. So for this situation I prefer a different approach - wrapping with electrical tape.

Before I begin wrapping plys of CF, I put a ring of electrical tape around the chain stay, just beyond each end of the section to be reinforced. The tape is wraped upside down - so the sticky side is out. These sections of tape will be used to start and end the compression wraps of tape. Mounting them before things are wet with epoxy makes it a much easier and cleaner step.

Once the CF sandwich is in place, I take off my gloves (so I have clean dry hands), and begin winding the tape around the stay. This too gets wrapped upside down - the inner (usually outer) side won't stick to the epoxy and by pulling the tape tightly, we get good compression.

Ultimately I wind from one end to the other, then reverse and wind back to the original end. Along the way, it's important to keep the tape as free from wrinkles as possible. Every wrinkle will cause a pocket of epoxy that needs to be later sanded down. And a big wrinkle could actually lead to a hump in the CF which would be nasty.

With this done, its time to poke lots of holes in the tape. Actually, in the course of wrapping, excess epoxy was driven ahead of the wrap and out of the layup. But we want to do more and the holes will allow more epoxy to migrate up and out of the CF. The whole setup gets heated by a nearby incandescent lamp to thin the epoxy and facilitate it's flow. If you click to enlarge the picture, you should see lots of little bubbles of epoxy on the surface of the tape.

I won't be able to return to this before tomorrow - but hopefully then I can show pictures of the raw finish.

Cheers,

Done Baking

noreply@blogger.com (Rick Guggemos) — Sat, 22 Nov 2008 01:52:00 +0000

Here's the main plate. This is viewed from the top and looks much like the surface of the last piece. However, when we turn it over, we'll see a different finish.

Unfortunately, there are a couple of defects on the bottom. Most obvious, a corner got folded over, apparently while placing the layup in the vacuum bag.

While not visible in the pictures, a close observation shows the defect visible through the top layer as a triangular corner which is lower than the rest of the plate.

There is also a stray fiber that got caught - which is strictly a cosmetic defect. But there are also some depressions in the bottom - apparently the table had some defects in its surface which I didn't detect.

All of this leads me to consider a different approach for the next time. Rather than using a bag on a table, I'm going to try laying a piece of plate glass on the table. This should provide a smooth lower surface. The layout w/ peelplys and breathers will be laid on this. Then a lay piece of bagging material over this and seal its edges to the table with a special caulk-like tape. This will avoid the difficulty of sliding the layup into the bag.

Having said this, the majority of this plate looks good, and should make some fine dropouts.

All up this plate weighs 310 grams - so 40 grams of epoxy was squeezed out in the vacuum. That said, my ideal weight was 250 grams and my realistic expectation was 290 grams. So we're just a bit pudgy. It seems clear that I started with too much epoxy to hit my targets. Also, I need to check my pressure next time to make sure that I'm pulling as much as I think (possibility of excess leakage in the bag). Nonetheless, this plate came in with a lower epoxy weight than the last plate so we're making progress. And there doesn't appear to be so much epoxy as to reduce the strength of the plate.

More later.

More Carbon Plates

noreply@blogger.com (Rick Guggemos) — Fri, 21 Nov 2008 22:36:00 +0000

Pictures! Yea!!!!
Sorry for the quality, its a very old digital camera and the color is off because these were taken without a flash.

Anyhow, these are some more carbon fiber plates under vacuum. Last time, some heavy Kevlar was applied where the axle nuts rest. Two problems with this: 1) It doesn't cut; 2) It doesn't cut. A $35 ceramic tile blade died in the jig saw trying to cut Kevlar. Note, it didn't have any problem getting through the CF - slow steady cuts worked great. Moreover, the edges of the Kevlar end up fraying where the saw tore through them - very unsightly. Meanwhile, some of the CF elders suggested that I experiment without and protective layer over the CF - so that's what I'm doing here.

The last plates were cut up into smaller pieces and showed now voids or soft spots - clearly the epoxy soaked through just fine. After some careful weighing of my raw CF stocks, and some further calculations, it appears that I added nearly 70% epoxy by weight to the final product. That's fine, but not as light as it can be. It may be that for this sort of heavy layup, and infusion technique might be best. Something to explore down the line.

Back to the pix (you can click on them to enlarge), you can see the rough outline of the larger plate being vacuumed. In the one picture, you can also see a 2x4 clamped down on top of the other plate - squeezing it to the work table.

This time my layups looked much dryer than last - but after weighing everything, the main plate has 175 grams of CF and had 175 grams of epoxy added. Once its cured, we'll weigh the plate and find out how much epoxy remained in it. I'm hoping that this will be lighter (by volume) than the last.

The hidden (by the board) plate is just a lever about 1" x 7mm (finished thickness) x 12". It'll be used for some deflection testing.

The main plate will be used for some sample dropouts and the remainder will be used for a variety of tests, including impact & tensile strength.

For this set of plates, a release film was used on the bottom side instead of a peel-ply fabric. This should lead to a layer of smooth epoxy - although nothing like a jell coat. So it's just an experiment. Just as the clamps on the narrow plate are an experiment.

You can see the dark spots where the epoxy is oozing through. Apart from the edges, there's not too much. I gave the edges an extra drink just because I apply epoxy from the center and they looked a bit dryer. Maybe next time we'll do with out the extra.

Just FYI, there is a bleeder felt under the whole setup
(inside the bag of course), and one over the top. The long edges of the big plate got an extra layer of bleeder on top - you can see the ridges running across the top of the bag where these end. You'll also note that the bleeder is much wider than the plates - so there should always be an unobstructed path for the air to reach the outlets for the vacuum pump.

That's about it for this time. See ya around.

CF Drop Outs

noreply@blogger.com (Rick Guggemos) — Sat, 25 Oct 2008 01:54:00 +0000

OK,

I'm working on CF dropouts. I want to use a new brand of rear triangles, but they don't work with any prefabbed DOs. This is because the chainstays taper all the way to the ends, which aren't parallel to each other. So, a round plug that fits into the end, is way to loose at its front. And, a Do that follows the axis of the stay, without a bend, won't form a parallel platform for the hub.

Anyhow, the first step is to make a plate from which to cut out the DOs. Luckly, I've come into some samples of very nice CF fabrics. The one that will be the base of the plate has 9 plys of UNI Cf in 0/90/45/-45 degree orientation. Three layers of this are used, creating a base 27 layers deep. On the outside, I'm using some 2x2 12K twill that is doubled layered, so the total sandwich will be 31 layers. Kevlar tape goes on where the axle mounts to protect the CF from the bolts.

So here are some pictures from my first plate. This is the backside - nice and flat with a stray piece of CF in the laminate. Unless this stray ends up in an exposed place, I won't worry about it. Note, the Kevlar hasn't been mounted on this side yet. That will wait until the DOs are cut out.

The next view is an edge of the CF that has been cut. All looks good from this slice in terms of bonding and compaction.

You can click on the pictures to enlarge them.

No indications of voids or dry spots. This whole plate weighs 65 grams. I expect that the dropouts will weight less than half this - say 30 grams. After adding the hardware for the derailer - it'll probably be 35 grams.

Typical aluminum DOs the come with many carbon rear triangles weigh around 110 grams (on my scale).

The stainless plate DOs that these are based on weigh in at 125 grams.

So, 35 grams for these sounds pretty good to me.

By the way, Blogger is turning my pix sideways for some reason - sorry.

Here's the front. I've laid the stainless DOs on top of the plate, then sprayed it with some gray primer - to show where to cut.

The yellow is the Kevlar. One piece of Kevlar picked up a spare piece of CF - but this will sand out easily enough.

Notice on the derailer side how there is a shiny rectangle. There was a bit of tape on the end of the Kevlar tape to prevent fraying. The rest of the material was pressed against a woven peel-ply - leaving a flat finish. Where the tape was left a glossy finish.

That's it for tonight. See ya next time.

Fabric Pictures

noreply@blogger.com (Rick Guggemos) — Fri, 05 Sep 2008 23:14:00 +0000

Normally, I work with unidirectional CF, and sometimes a cosmetic layer of plain weave. Let me explain. In a plain weave, there are threads going both up and down, and side to side, each go over one thread then under the next. It's about as simple a weave as can be imagined. If you know that CF only exhibits strength in tension, then this might sound like a great idea, because one layer can deal with tension in two directions, each at a 90 degree angle to the other. Unfortunately, this doesn't quite work. In weaving the fabric, the threads get bent up and down - they don't lie in a straight line. So we can say that they are 'crimped' and these reduces their strength. In fact, the strength to weight ratio of CF is negatively impacted by the need add epoxy, to align with the vectors of stress (adding layers), and because of crimping. This latter factor is the reason that a woven fabric is usually reserved for an outer 'cosmetic' layer.

Uni-directional CF is an interesting beast and comes in several forms. Because it is uni (one) directional, it doesn't have crimps. Also, it's fairly easy to align with the force vectors, although multiple layers may be needed to pick up all the force vectors. Multiple layers aren't really a problem for us because we'll use enough CF to require multiple layers anyhow.

CF is held together in one of several ways. The first is to run a thread (generally of something other than CF) across the width of the fabric (which is sometimes narrow enough to be called a tape, or wide enough to be a cloth). The cross thread is held in place by some sort of glue. Another approach is to glue a veil (very thin layer of randomly aligned threads) of fibers to one or both surfaces of the uni. The later approach tends to be less visible afterward, but often doesn't allow as much bending of the uni to follow the shape of a structure.

The uni with the cross threads is more common, but the cross threads are thick enough that, even when they are turned in towards the work, they tend to print through somewhat as a ridge in the finished material. Also, its easier to damage the uni carbon threads by rubbing something (anything) across their surface. Each thread is made of very fine strands of CF, and abrasion starts to pull the individual strands away from the thread. With the veil, the surface is better protected, and often on both sides. However, with wider uni fabrics, the veil so limits bending that it doesn't seem to be used much. However, there is an interest form of CF tape made with a veil backing. A one inch tape will be divided into three strips of CF, each with a space between them. The veil runs edge to edge and so crosses these empty strips. Using this tape, it can be split length-wise along these gaps, allowing it to better follow contours. So where one tube joins another, the end of the tape can be split (as an example) allowing the middle CF strip to bend up along the length of the intersecting tube, while each of the other strips angles off and wraps around the intersecting tube. I'll probably have to add a picture of these later to illustrate this clearly.

Woven CF fabrics can come in a number of different weaves, which I won't try to describe here. But, some of the fancier weaves offer more flexibility than a plain weave, and often less crimping as well. This makes them better structural solutions, especially for more complex shapes. In a few moments we'll see more regarding this.

It should be noted that some of the challenges of handling uni-fabrics can be overcome using pre-preg CF. However, pre-preg requires a freezer for storage and an over for curing. Currently, my little shop has room for neither of these appliances - so pre-preg is out.

There are some other venues were pre-preg isn't the chosen solution. And for these
variations on uni-fiber have been developed. Most of these solutions are very high-tech, at least in terms of how they are manufactured. Only a few manufacturers have the facilities to create the best of these fabrics. And, these fabrics aren't generally available except on special order in very large quantities. Thus, they haven't readily been available to custom frame builders.

Recently I spotted someone selling 150 yards of such a fabric - which is much more than I can use over the course of several years - so the purchase was out of the question. But I made contact with the individual who is in the aero-space industry. He works for a major company that you've worked for, and my best guess is that his work is in the defense sector. But that's all I can share.

Anyhow, I asked questions because I wanted to know more about this stuff and it's applicability to framebuilding. He offered to sell me a small lot, so I bought 4 linear yards. Here is a picture of some in the raw:

If you look closely, you will see that there are two layers of uni CF. The top layer is clear, but look at the edge and see that there is a layer behind running at 90 degrees. What is this? It is non-crimped +/- 45 degree uni-directional carbon fiber. The stiching you see helps to hold its shape or body, but it allows the fabric to be very flexible and drape wonderfully around complex shapes (think of a bottom bracket where 3-4 tubes join together around the BB shell). Moreover, each layer of this fabric is about as heavy as one lay of my normal uni-CF - so only half as many layers need to be cut and applied. Naturally, each layer soaks up more epoxy, and more work has to be spent workign the epoxy thoroghly through the cloth. Also, I still need normal Uni to add a third major force vector plus occassionally other lesser vectors. This is very cool stuff and I hope to have some pictures for you soon of it in use.

My new friend also sent me samples of a couple of other interesting fabrics. Look at this:
When I first looked at this, I thought it was a 1x1 plain weave using 12K bundles - this is the now fashionable large checkerboard effect seen on a number of new bikes. Closer examination revealed that it is something else. First note that there is a veil above the upper surface. The backside has the same veil. Looking at the edges, this is 2 layers of CF, with the treads running at right angles. Because there is no stiching, I'm guessing that there is veil between the layers to glue them together. Also look at the weave, it doesn't make squares, but instead forms rectangles. This is a twill weave. Both directions of fabric run over 2, under 2 patterns, and adjacent bundles are staggered by one thread creating the diamond like pattern. My best guess is that when wet out, the veil becomes week and that this should form nicely over bends and curves. It has fewer crimps than a plain weave, but should still offer a nice cosmetic finish. Once I've experimented with it, I'll fill you in.

The next and last fabric is a bit more of a mystery to me. Here are two pictures, one where it has unraveled a bit, and another where the fabric is intact.
From the unravled edge, we can see that there's a whole lot of CF going on. Also, that the fabric is stiched through and has a veil on the top.

My best guess is that this has from 4 to 6 layers of CF. Looking at the edge in the second picture, you can get the sense of all the layers. Also, it looks like there may be some intermediate layers of veil. Without trying to take this apart a layer at a time, it's hard to get a clear picture of the internal structure. And because I only have a limited sample, its hard to investigate in a destructive fashion. Nonetheless, it looks like it has at least 3 directions of uni (0, +45,, -45 degrees) and possibly 4 directions (0, +45, -45, 90 degrees). With all of these layers in one cloth, very few pieces of this should need to be laminated together. Also, most force vectors should be addressed by this one piece of cloth. So it could speed construction significantly. It will take more effort and care to work the epoxy through this cloth. And, it may not drape as well as the other examples that we have. But like the rest, it's going to make for some fun play.

Well that's it for tonight. I'll probably take a cut at editting this a little tomorrow - meanwhile you can enjoy the pix.

Carbon Pix

noreply@blogger.com (Rick Guggemos) — Fri, 05 Sep 2008 01:53:00 +0000

OK, I promised some pictures and here they are. Hopefully I can format the page so that the pictures align with text.

First off, let's look at some CF bonded to an aluminum tube. In this case, it's a simple solution for a head tube. Use an aluminum head tube for structural purposes, wrap it in CF, and then bond the top and down tubes to the CF. First though, there is a layer of fine fiberglass followed by a layer of CF veil. The later is like a felt, only very thin and porous. Between these two layers, and the epoxy they hold, the CF will be insulated from the aluminum to avoid galvanic reactions.

On this sample, multiple layers of unidirectional CF tape are wrapped around the tube. These are wound at +/- 45 degrees from the axis of the tube, to cover a variety of forces that may be imposed on the joint.

For this demo, heat shrink tape was used to compress the sandwich while curing. Also, just to speed things up, I used a little heat. Around the CF, there is a release layer of plastic film (almost like less-clingy Saran-Wrap), which has a pattern of small holes that will allow excess epoxy to bleed off. On one side of the tube, a layer of bleeder material was placed over the release film. This is like a synthetic cotton batting, which will absorb excess epoxy. When a vacuum is used for compression, it also provides an air channel from which the vacuum can pull.

Normally, the bleeder layer would go all around the tube, but this is test to show you different options. After this was all wrapped, a heat gun was used to shrink the tape. As this was done, damp spots started to show in the bleeder material. The heat from the gun not only shrunk the tape, but also started to lower the viscosity of the epoxy - which helps to remove excess and helps to remove air bubbles in the fabric.

At this point, the whole shabang went into the over (the one in our kitchen), which was then turned on to 175. Once it was at temperature, this was held for about 10 minutes. Then the thermostat was raised to 225 and the timer set to 20 minutes. Approximately 7 of the 20 minutes were spent raising the temp to 225.

At this point, it was removed from the oven and allowed to cool enough to handle. The tape, bleeder, and release film were all removed - and the piece was essentially cured and ready to go. This is the state from which the pictures were taken. As always, pictures can be enlarged by clicking on them.

Here is the side that had the bleeder layer. Note that the lighting exaggerates the texture. The overlap in the layers of shrink tape leave a spiral outline on the CF. Also, most of the texture on the surface is an embossing by the bleeder and release film sharp wrinkles are from the release film and larger textures from the bleeder. Surprisingly, most of this texture can be removed with a layer of clear epoxy. Now here is the side without the bleeder. Notice how much smoother it is. Also, it has a deeper sheen to the surface. If you saw this in person, you would notice the depth provided by a clear coat. On this side, the excess epoxy had no where to go. Some is still distributed in CF (making for a weaker product), but some has risen to the surface forming the finish you see. The overlap of the tape spiral is still visible, but not as much as on the other side.

Now here is another head tube.
It's not an experiment - but a real head tube. It has cosmetic layer of plain weave CF on the top, and was created using a full wrap with the bleeder layer. Unfortunately I don't have a picture of it as it came out of bag, but believe me when I say it had a distinct texture. Less of the bleeder printed through with this, but the texture of the CF fabric was very nearly as strong as if it had never been epoxied. To this, I've painted on a layer of epoxy. This was undiluted, so it's rather thick. There were some runs, which have begun to be sanded out with 400 grit, none the less, you can see the depth of the finish - and when all polished up it will be very impressive looking.

Here's an experiment that didn't go so well...
The picture isn't well lit and you'll want to enlarge it to see what's going on. I tried to run a dart or arrow of plain weave from the BB out onto the chainstay - just for decorative purposes. The problem with plain weave (in particular) is that the edges tend to self distruct. Thread by thread fibers fallout of the weave. The smaller the piece is, the more this happens. I'm working on some solutions to this problem, but meanwhile take a close peak. Besides not having a clean edge to the plain weave layer, you can see a couple of other things: 1) signs that I used shrink tape on the chain stay; 2) the ends of the CF threads are unwinding under the press. The later is most noticable in the center of the picture - two threads on the bottom of the plain weave layer.

Now, this doesn't pose any structural problems - heck this layer isn't structural to begin with. But, it's not the result that I'm looking for - so back to the drawing board for this one.

Some of these issues go away when working using pre-preg (pre-impregnated) carbon fiber. The epoxy in the fabric holds things to gether when handled, and the tack of the fabric makes it easier to hold pieces in position as the CF is layered on. However, pre-preg needs to be stored in a freezer and then cured in an oven - and I don't have room in my shop for a freezer or a frame sized oven - so I stick to normal uni-direction dry CF and wet epoxy layups.

Tomorrow, however, I'll share some pictures of some rocket science that I'm sampling which starts to close the gap between those to processes.
Ciao

Ramblings

noreply@blogger.com (Rick Guggemos) — Wed, 30 Jul 2008 01:55:00 +0000

After lots of talk about carbon building technique, I thought it would make some sense to show some pix. So I'll be shooting some 'intermediate' stages of work to use in show and tell - stay tuned.

This season, I've been riding a prototype bike - designed to test some long reach brakes. The fork is straight-legged steel, but with fairly light weight legs - which lends it a nice ride. It's raked at about 53mm to shorten up the trail, because the bike is riding on 700Cx28mm tires.

Generally, I like the ride and handling quite well, but there is one funky handling quirk When rolling into turns at over 14-16 mph,it's sometimes necessary to turn my inside knee towards the apex in order to tighten my line. It appears that there's just a little too much tendency to hold the line, and that the bike may benefit from even less trail, but I'll have to try making another fork to test this out.

My tires have been a set of Hutchinson Top Speed. Lot's of folks look at them and don't believe that they are a real 28mm width, but true that. The key thing is that they're giving me a really cushy ride and they roll like anything. Part of the credit for rolling goes to a set of Record hubs, but note that these were purchased (as wheels) used, and haven't been serviced at all since I got them. Consequently, I think that the tires deserve their share of credit for low rolling resistance.

Anyhow, I didn't think too much about the tires when mounting them. They were in the equipment stash, and of the proper size - hence no cash outlay - good enough for my purposes. Recently, I was testing out a fixee with some nice Gran Bois 700Cx30mm tires. At about 10PSI lower pressure, the ride wasn't as good. Part of the difference is the fork. The fixee is built with an antique set of Reynolds 531, including pre-curved blades with the old English style profile. For those not familiar with this profile, it is longer and narrower at the top when it connects to the fork crown than the more common continental oval. Anyhow, these blades are definitely stiffer than what's on the prototype bike. That said, the frame is stiffer on the prototype.

The Gran Bois are great tires, and I can probably reduce their tire pressure some more. Also, they haven't had enough miles to break in. But the difference in rides between these two bikes is quite remarkable, despite my anticipation that the Gran Bois would ensure that the Fixee was more comfortable - leaving me with a riddle.

After searching online for more info on these Top Speed tires, it became clear that Hutchinson has stopped offering them in the 700Cx28mm size. What a Pity. Anyhow, digging in the equipment stash turned up another pair, same size (although different color) still in their packaging. The printed spec is for a carcass with 66TPI. This surprised me too. I don't usually think of 66TPI offering a very compliant carcass - but there you are, the ride of these is great.

Now I'm really mystified. It looks like it's time to try swapping front wheels on these bikes and riding them back to back. It's hard to believe that the tires are creating the difference in ride, and the wheel switch should help establish if this is true.

Meanwhile, its nice to have stumbled onto these tires and have a spare set, but its sad that they aren't made any more.

Changing topics, let's consider the evolution of handlebar shapes. Along with the evolution to 'anatomical' handlebars, we've seen a push away from long and deep (sometimes called Belgium drop) bars. I've never found an anatomical bar that seemed more comfortable to me than a traditional bar, especially when down in the hooks (which is where the 'anatomical' part of the design is typically located). Hence, they've never done much for me. But the loss of availability of a range in sizes of drop and reach has felt like a loss. So maybe I'm a luddite.

The very latest anatomical bar designs, however, seem to be onto something which may be indicative of modern riding styles. Several mfg's are now offering bars comprised of smooth curves, which quickly bend backwards under the brake levers. Like most anatomical bars, they have a very short ramp leading up to the brake lever.

Essentially, this leaves the rider with several riding positions: top of bars, on the brake hoods, in the hooks, and at the rear of the drops. Note that each of these positions is equally close, or closer, than their respective position on traditional bar (because the hooks pull backward more, and the drop tends to be less extreme than on a traditional bar). Meanwhile, they don't really offer a position on the ramp behind the hoods, because the ramp is so small.

So what's going on here? Are we trying to sit more upright while riding today, than did riders in the past? Absolutely not. But, many riders today seem to stress long and low stems. Often this situation is exacerbated by the use of a threadless headset without the compensation of a longer head tube. Hence, to keep the brakes in reach (not to mention the hooks), it helps to have a shorter handlebar. And to keep the drops in reach, it helps if they don't drop as far as traditional bars, plus having them extend backwards more.

"So what?" you may say, the stem goes one way, the bars in another, and we end up in the same place. But that's just it, we don't really end up in the same place. We lose the ramp as a hand position, and in my experience its a great position - with a low likelihood of aggravating the ulnar nerve. In my book, that's worth thousands of dollars by itself. Also, the difference in body position is reduced when moving the hands from the tops to the drops. Old bars had the tops closer to the seat, and the drops lower and farther away from the seat, as compared to the latest examples of anatomic bars. So, one's body position is less likely to change as much on an anatomical bar when moving between these grips - and that's the first reason to change grips.

Does anyone besides me care about these changes? I don't know, but it's food for thought when trying to tailor your position on the bike.

Finally, in another ludditish (word?) rage, let me take on cassettes (cogs not music). It took me a long time to understand the fascination with cassettes using 11 or 12 tooth small cogs. Let's face it those are for speeds in excess of 40mph, which very few people will achieve except going down hill. You may point out that we all spend our share of time going downhill, some would say I go downhill at an ever accelerating rate. But, pedaling down hill is largely a waste of energy. The exponential growth of wind resistance means that pedaling will add very little to your speed and is unlikely to decrease your elapsed time.

Yes the pros pedal down hill in the Giro, TdeF, and Vuelta - and you should plan to do so also, when you're riding for a pro team in the Grand Tour. But, that's probably not likely to happen (if only because you're reading this instead of training), therefore you shouldn't worry about pedaling down hill or about having an 11, 12 or even 13 tooth cog.

This leaves the question of why the big 3 push these over-geared cassettes on us? I think its because we're all weight-weenies at heart. Lower the size of each cog by 2-4 teeth and you'll lower the weight of your cassette. Have you seen what folks will pay for a Ti cassette just to save a little weight? And the mfg can save weight just by using smaller cogs, which probably also reduce the cost to mfg (less material). Hence most cassettes start with an 11 or 12 tooth cog. Ugh. I wish SRAM would come up with a 13 or 14 by 27 tooth Red cassette. That would be cool. But that wish isn't likely to be granted soon.

Ok, carbon pix soon, and maybe some more surprises.

Cheers!

Quickee

noreply@blogger.com (Rick Guggemos) — Fri, 11 Jul 2008 02:53:00 +0000

Here's just a little update. I'm getting ready to sag a bunch of my riders on RAIN (Ride Across INdiana) on Saturday. We'll leave town about noon tomorrow with two sag vehicles and 8 (I think) riders. Tonight I've been pulling together my pit gear. I won't be able to replace shifters, bottom brackets, headsets, or anything but 10 speed Shimano compatible cassettes, but should be set to tackle anything else. Either the variety of standards, or size of tools required, were my two criteria for what not to bring. It's not that I expect problems, but being prepared is the best defense against having to fix anything.

Moving on, my new Ti parts arrived this week. So sexy. Between the BB and head tube I expect to remove about 200 grams from my typical carbon frame with these parts. They're also beautifully made.

My current build is coming along nicely. If you're a long time reader, you know that I'm a keel builder. That is, focus on the head tube, down tube, & chainstays, to ensure a straight keel between the wheels. Then fill in the rest. The reality is, however, that I usually connect the seat tube to the BB first - and then let it just wave in the wind until the keel is done.

With a bagged carbon frame, there are a number of ways to do things, and I chose a sequence slightly different from how I build steel. I begin by mitering the chain stays (which have a mono-yoke) to the BB, then glue them together in a jig with aerospace epoxy adhesive. Once this sets up, 8 layers (more will be added latter in the process) of uni-carbon are wrapped around this joint - five run straight and form a 'U' when viewed from the side, the remaining layers are angled about plus/minus 25 degrees. Each angled layer includes both plus and minus angles - as I'm using narrower strips of carbon - so the layer has a crossing of the two angles, but nets about the same amount of fabric as one of the straight layers. As a final step, three layers are wrapped around the yoke of the chain stays (90 degrees to the main reinforcement). After fiddling to make sure that all is flat and smooth, the yoke portion gets wrapped with heat shrink tape. This serves to flatten this area nicely, indicate if there are problems in the wrap around the BB shell, and helps hold the rest of the layers in place until the vacuum is applied. Note, there is a concave space where the top and bottom of the chain stay butt up to the BB shell. If the main wraps are too tight, they will lift out of this area - making a bubble and potential stress riser. So with gloved hand, I check to make sure that the tension on the wraps is correct.

This then gets put into a vacuum bag, and as the air is evacuated, I work the bag to lay as flat as possible all the way around the BB/chain stay joint. The uni-carbon comes with something (it varies) on the back to hold the threads together and in parallel. With a good vacuum job, its possible to see this backing through the carbon when the joint is later unwrapped.

The finished assembly is inspected, and then sanded with 180 grit to prepare to bond tubes and more CF. Note, I could use a peel-ply that leaves a thicker layer on epoxy on the surface, with the pattern of the fabric embossed in the epoxy. This makes a good surface for bonding other bits too. However, I find this fabric a bit stiff and unwieldy for working around this sort of joint. Hence the sanding of the finished surface.

Next (reverting to my old habits), I miter and bond the seat tube into place. With steel, I'd just use a pattern from Bike Cad to mark the miter. This works here, as well, but only up to a point. At the rear, the yoke of the chain stay interferes with the fit of the seat tube, and the seat tube therefore needs to be trimmed down carefully. Once the proper fit is established, all surfaces are cleaned up with rubbing alcohol and allowed to dry. The fit over everything is checked one more time in the jig. Then a layer of aerospace epoxy adhesive is applied around the base of the seat tube, and the tube is put into place, and the jig is closed down on the seat tube to hold it in place. Supposedly the parts can be worked within two hours of bonding, but I generally give them overnight.

Meanwhile, I've been preparing the head tube. This one gets my traditional aluminum head tube with a CF wrap. Actually, a fine layer of fiberglass goes down first, then the CF. In this case, I used some 5.7 oz plain weave CF. Over the CF goes a plastic peel layer in which I've punched a lot of small holes (pin pricks actually). Over this goes a layer of synthetic cotton batting - which serves to suck up any epoxy squeezed out of the CF. Finally, I give it a tight wrap of heat-shrink tape. Once its all stabilized (tape on the ends or whatever), I use an electric heat gun (like some folks use to remove paint) to quickly shrink the tape. With a head tube set up for cure, I usually put it in the oven at about 175 degrees for 30 minutes. This speeds up the cure, but also helps to bleed off excess epoxy.

This process seems to work because the whole piece is evenly coated in epoxy (which shows as a glossy sheen), but very little of the texture of the CF cloth is lost. On the final layer (once joints are done), we'll want a thicker top coat of epoxy to provide a smooth base layer for the painter - but until then, we want to use the least epoxy possible to do the job - and this method seems to work very well at meeting the goal.

Now its time to do some measurements to mount the head tube in the jig, and position it correctly relative to the BB. Key issues are, of course, the head tube angle, effective top tube length, height of the bottom of the head tube. The later are designed around the fork and headset which will be employed, to ensure that the prescribed head tube angle is realized in practice. After a bit of fiddling, a satisfactory positioning is achieved.

Then, its time to begin mitering and fitting the down tube. On a lugged steel bike, its possible to make the down tube a half inch long, fit things up in the jig, then mark the excess from within the BB. That doesn't work here with a solid BB. So, I start by fitting the down tube to the head tube first - using a protractor to check that my angle is correct. Then the BB end is mitered, but it's left intentionally long. Now I fiddle to see that my down tube/seat tube angle appears correct. If not, there's something wrong with the head tube positioning. This is just a double check, but nonetheless an important step.

If positioning looks good, I carefully start to carve the BB miter back until I can fit the tube into place. If all has gone well, both ends have nice tight fits and I don't have to recycle an expensive piece of CF.

At this point, I once again check all fits on the jig, then clean the down tube, head tube, BB, and seat tube with alcohol. Again, adhesive gets applied, this time to both ends of the down tube. At the bottom it is fitted to the BB and to the seat tube. Once more, the jig and fits are double checked - before anything can set up.

OK, that's how far the current frame is. We'll next have to modify the BB joint to ease the process of draping layers of CF thereon. So stay tuned to learn more about finishing this important joint.

Cheers.

Post ride update... The only mechanical I had to deal with was.... a bottom bracket. At the first stop, one rider had a crunchy dragging BB. Fortunately it was a cup and cone style, as I hadn't brought any spares. The bike was borrowed, and both the axle and one cup had some damage in the races. Also the bearings were caged, which are easier to keep track of, but which I find to offer less good results than loose bearings.

Anyway, I was able to repack the BB and adjust it so that it would spin smoothly. Then I drove off to purchase a spare (just a basic 113mm Shimano cartridge square taper BB). Anyhow, the rider made it through the ride without further issues and I never had to install the spare.

Congratulations to all the riders who completed RAIN!

What's new

noreply@blogger.com (Rick Guggemos) — Thu, 03 Jul 2008 00:56:00 +0000

Let's see, he said as he stroked his chin. "Hmmmm.....

Now that the weather is warm, I'm working hard to catch up on my backlog. Carbon has been at the fore of my efforts as noted in the last post. Along these lines, I'm having some fun and showing great progress in a number of dimensions.

I've begun working with Edge Composites for tubing and rear triangles, and they're great. They'll build to my spec, and can turn around custom requests in pretty short order. A very simple example, I can now spec a tube a either plain uni-directional fiber, or any of several weaves of overweaves (from the traditional burlap look to the newer 12k checkerboard looks). So riders get a choice of aesthetics and performance. On the front triangle, plain uni carbon saves about 10% in weight, on the rear triangle it's closer to 20%. Not bad. But, for those who don't worry about fractions of an ounce, there is the option to choose their favorite fiber look. We can even turn the weaves on an angle for one more dimension of customization.

Speaking of rear-triangles, Edge molds the cable casing stop into the chain stay - so that eliminates holes and rivets - which is a good thing.

They've also provided their input into my plans for CF dropouts. This option is especially appealing to me for track frames where no one is manufacturing a carbon compatible dropout. That may be changing as there is another player getting ready to announce some super neat metal dropouts for CF rear triangles. I can't say any more for now, but I'm getting excited about that.

I've also been exploring various options for BBs and head tubes. Eventually, I think these will be pure CF, with the option for BB30 bottom brackets. In the meantime, I will shortly have some nice Ti BBs. These are thinner gauge metal than what you would see on a welded Ti bike, and will be reinforced by the CF over-wrap, rather than having that merely be a surface to which other tubes are bonded onto the BB. I think this will be lighter than my current wrapped Aluminum BBs, and have longer lasting threads. Plus, Ti resists electro chemical interactions with CF better than just about any other available metal. In a related move, I'm moving to CF head tubes with Ti rings bonded into each end. The Ti gets reamed and faced for the headset, but the CF tube provides the structure for the front end. Much less weight than a wrapped aluminum head tube, and again the chemical stability of Ti. So, all of these parts represent steps forward - and will help distinguish my CF frames from the run of the mill

On a different front, I've been constantly refining my vacuum bagging technique. It's easy to shove some parts in a bag, turn on the vacuum, and wait for them to cure. What gets tricky is maintaining the layers of wet CF in alignment and snuggly wrapped around the tube. A loose piece can easily create a bubble between layers that will become a source of failure. Even tricker is doing this in a manner where we get a nice smooth finish on the outside of the part. Many forms of vacuum bagging work against a mold - which is highly polished. The CF surface that lays against the mold (often with a layer of gel-coat between) is essentially finished when done.

I could create molds for my joints - some manufactures do. But, that limits the combinations of angles and tubing sizes I can use (either that or have a nearly infinite range of molds available).

Instead, I'm wrapping the joint with a layer of smooth plastic release layer. The plastic has small holes that allow excess epoxy to weep out into the bleeder felt. This layer of plastic has to be fashioned to follow the contours of the joint - so it doesn't wrinkle and cast the wrinkle into the epoxy. The bleeder felt also has to be arranged so as not to wrinkle. I've taken to fitting multiple pieces of felt to the joint - because it won't stretch to fit. Finally, it's important to arrange the 'bag' around the joint in a fashion similar to the release layer - again to avoid wrinkle. The net of practice is that my joints are coming out of the bag much better finished - and needing much less touch up before they're ready for paint. Cool.

Anyhow, thats enough words for tonight. See you next time.

Playing

noreply@blogger.com (Rick Guggemos) — Sun, 15 Jun 2008 00:26:00 +0000

I get to try and test a variety of things bike-wise as part of being a builder. After all, its important to understand what works, and what doesn't. Lately my focus has been on brakes. Looking at alternatives that work in various situations. One challenge, in particular, is fitting brakes over fenders and wide tires - especially if the rims are on the narrow side.

I set up a prototype bike with a fork sized to use the longer armed Tektro double pivot brakes, and the brake bridge is set to test the Paul center pull brakes. For testing, the wheels are Mavic MA3 on Record hubs - something purchased used (cheaply) on eBay a couple of years ago. The tires are a pair of 700C x 28 Hutchinson Top Speed - which no longer appear to be in their catalog (nor is there anything else like it). Which is a pity.

This has been a favorite tire of mine lately. It's not an expensive or fancy tire. Some folks look at it and don't believe it's a 28 - but that's just the cross-section (egg like) at the top of the rim throwing them off. In reality, it's an easy rolling tire despite having low thread count and an anti-puncture layer. Typically, I run them at about 90 psi - which seems to sag about right under my weight. As we've discussed before, a compliant tire reduces rolling resistance on the road (as opposed to a test drum). So I've used these tires many times in roll offs to try and convince the reluctant of the benefits of soft and fat (tires, not bellies).

The Top Speed corners very nicely, as wider tires are wont to do. Hands and butt feel much better after hours on these tires than they do when riding on 23s. Very comfy is my official rating. And these two factors are often forgotten when folks evaluate tires. If you're riding for long periods, faith in road holding and physical comfort make a big difference, and probably allow you to gain more speed than a new set of expensive aero wheels.

My test setup is Campy based, which means that there are two (2) quick releases for each brake. One is in the brifter, and one at the brake. Theoretically, one can open the brakes wider for wheel removal. The theoretical part relates to how wide the brakes open when they have no cable tension on them. The Paul appears to do a bit better than the Tektro in this regard, but both open plenty wide for a set of 700C x 28s. They should handle 700c x 32s as well, and it looks like the Paul's will also clear 35s or even 38s.

Both brakes are positioned so that the brake shoes are at the bottom of their slots. This isn't the ideal location, but it's what demonstrates the greatest tire/fender clearance. The Paul's, again, offer more clearance. Having said that, my preference is to use cantilever brakes with fenders.

With fenders, its ideal to set the hight of the fork crown or brake bridge based on where you want the fender to sit relative to the wheel/tire. When using crown or bridge mounted brakes, the position of the crown/bridge is dependent on the needs of brake in order to get a good interface between the rim and the brake pads. Sure, there's a slot where the brake pad can be raised or lowered on the brake arm. But this still offers only limited range with which to work - and ideally (if only for aesthetics) we'd like to have the brake pad centered in its slot.

The net of this is that two different factors want to determine the distance from the axle to the crown/bridge - and sometimes these factors disagree as to the proper position. Back in the old days, there were many more lengths of brake arms available - making this particular fitting issue less difficult. Because we don't have those choices today, a cantilever (or other frame mounted brake) makes life easier. It is fitted to assure good rim/pad fit, while leaving the crown/bridge to be set at a distance that works well for the tire/fender combo chosen. And, that's why I feel partial to cantilevers for fenders.

It should be noted that the Paul center pull brakes are available for mounting on pivots brazed to seat stays/fork legs - making this another good combo.

But, what about the brakes I tested? Are they any good? A couple of points that should be noted. First, both act very rigid, avoiding brake squeal. This is impressive given the length of these brakes from the pivot to the brake pad (again this was maximized on the test bike). They also feel very firm under hand, and grab harder the stronger one squeezes them. This is an area where many modern brakes are superior to many of the older brakes. Too many older brakes seemed to flex more as more pressure was applied. Not these two.

Neither was the hardest grabbing brake that I've ever tried, but both did fine for me, and under these extreme circumstances (note that bike and rider all up are approaching 240 lbs, while the wide tires provide great braking traction). Having said that, brake grab can be tuned with various brake pads, and different riders like firmer or sticker pads. Stock, these worked fine for me, but some riders will want softer pads.

Taken as a whole, its clear I prefer other solutions for mounting fenders. But, having said that, either of these is a great brake - and I'd be happy to have a pair of either one under me out on the road.

Often, the press pans Tektro (or private label versions thereof). But I think that this is marketing bias. They are nicely finished, smooth operating, easy to fit and adjust, and have the fundamental key attribute of good brakes - they're stiff. And, again, we're talking about the long arm version. The more common short arm version can only be better for stiffness. Yes, lighter brakes are available, but this isn't a critical component for weight reduction. And typically, Tektros are so nicely priced that I have to encourage folks to give them fair consideration if the need arises to replace their brakes.

That's it for now. See ya soon

Carbon Carbon Everywhere

noreply@blogger.com (Rick Guggemos) — Sun, 01 Jun 2008 01:35:00 +0000

Look around, carbon fiber is everywhere. For only $269 you can get a decorative CF panel to stick on the pillar between the front and rear doors of your Scion! Yep it seems to be ubiquitous.

Only a year ago, prognosticators in the composites industry were predicting a major CF shortage. Looking around at suppliers, not all of them have all products in stock. That said, it's easy to find the materials I use in frame building. So that's a good thing.

A little known fact outside of the industry is that carbon fiber tubes cost about the same as high end steel tubes, such as from Columbus or Reynolds. True that. Oh and yeah, I said tubes. In fact I source my tubes from the same place as Trek. Did you know that Trek and many other bike manufacturers assemble their frames from tubes? For the consumer, that's not an important issue. But marketers have done a good job of selling the idea that CF frames are built of a a single carbon fiber monocoque - not assembled from tubes. So consumers don't like the idea of joined tubes and manufacturers don't talk about using CF tubes.

Well I'm not afraid to admit to working with tubes. The fact is, filament wound tubes can be manufactured to tighter specifications than a complex molded part. Which means that tubes offer the opportunity to build stronger and lighter! Yipee!

How these tubes are joined together is the real heart of the building process. And, for many manufacturers and frame builders, joining offers the potential for product differentiation. And I too have been working on my proprietary methods - with some success.

Most builders & manufactures use some form of wrapping the joint in CF and epoxy. Within this method, there are two primary approaches: a) wet wrapped CF vacuum-bagged until cured; b) pre-preg CF wrapped, heated under pressure in an autoclave until cured. The second approach is heavily used by manufacturers. It's an easier method to control the amount of epoxy in the CF (because it comes pre-impregnated), and pre-preg is relatively easy to handle while setting it up to cure. Two problems exist for this method in small volume production: a) Autoclaves are expensive; b) the product is molded - molds are expensive and limit dimensional flexibility. So, pre-preg is ideal for volume production.

Wet wrapping involves several steps. First, the layers of CF need to be cut out with the fibers oriented to plans. CF has little compression strength, so it requires fibers to be aligned in a variety of directions so that any force on the joint will be compensated for by fibers working in tension. In fact, if CF had the same strength in compression as in tension, we could make much lighter frames - using much less CF.

Anyhow, CF we use (except for cosmetic out layers) is unidirectional. That is, it isn't woven, all the fibers run in one direction. Various methods are used to hold the fibers together prior to being laid up with epoxy. None of these methods are perfect. So just cutting out the patterns on the dry CF can be difficult and requires a sharp scissor.

After the layers are cut out, we prep the tubes. This means lightly sanding the surfaces and then cleaning them with rubbing alcohol or acetone. The goal is to have clean bare CF on the tubes for bonding.

Then we mix up some epoxy. There are various approaches to mixing including: a) Electronic scales; Graduated cups; Calibrated pumps. Any of these approaches will work if care is taken. Once the epoxy base and hardener and dispensed, we have to mix them together thoroughly. This usually has the result of infusing oxygen bubbles into the CF - which we will address later.

The mixed epoxy has a limited pot life. By choosing different hardeners, and being sensitive to the ambient temperatures, it's possible to adapt the pot life for the task at hand. Note that there is a general rule that the longer the pot life, the longer the cure time. So we want to limit pot life to what we really need to assemble a joint and get it ready for curing.

Next we need a flat surface, which can be covered with saran wrap or wax paper (to keep the surface clean). We take our CF pieces and lay them down one at a time. Pour some epoxy on top and use a scraper or squeegee to spread the epoxy between the fibers. We want to avoid having the CF be soaked in and dripping with epoxy, but we want it to be full of epoxy. Depending on the setup, we may do this to all the CF pieces first, and them layer them on the joint. Or, we may apply each piece of CF as it gets wetted out. In either case, we end up with our tubes wrapped in layers of epoxied CF.

Over this we put a layer of material that won't stick to the epoxy. A mylar film can be used to get a very smooth finish, or a teflon coated polyester fabric can be used. The later gives a rough surface, but is better at allowing excess epoxy to flow through. And we want it to flow through to the next layer - which is a synthetic cotton batting. This batting performs two tasks. We will put this whole contraption in a sealed plastic bag, and use a vacuum pump to suck out all the air. The external air pressure will act as a giant clamp holding things together during curing, but more importantly, it will compress the layers of carbon fiber in the joint. In so doing, excess epoxy will be squeezed to the surface, and the batting will catch and hold this excess so that it doesn't enter the pump (which would be a disaster). Also, the batting provides a channel through which the pump can continue to suck air even as the bag collapes. Otherwise, the bag opposite the vacuum fitting would get sucked into the fitting and stop it from evacuating the rest of the bag - which would do us no good.

In the process of sucking epoxy through the layers, we hope to make sure that any voids in the CF are filled with epoxy and any air bubbles are pumped out. The reality is that this will never occur perfectly, but with good vacuum pressure we can eliminate enough voids and bubbles to ensure a strong, quality joint.

A key to making all of this work is holding the tubes together, in the proper position, as the CF is wrapped on, and until the epoxy cures. A number of approaches work, from fixturing the tubes to gluing them together.

I like the later approach, as it's possible to assemble a full front triangle and then vacuum the joints one at a time. But the bonds are fairly delicate and this got me thinking of a better way to join tubes. I've developed a proprietary method that I call full surface bonding. Without giving away too much, bond a solid surface, not a hollow tube to the adjoining tube.

How strong is this? Well, I wouldn't ride a bike so built without CF wraps around the joints. But, the point of failure is delamination of a tube surface. Think of it like this. We have a plain tube and one that is mitered. The mitered tube is bonded to the plain tube. When this joint fails, it is the surface of the plain tube that is failing - not the adhesive and not the mitered tube. In other words, this joint is as strong as it can be given lamination strength of the tube to which it is bonded.

One notable feature of this method is that it adds negligible weight to the joint. As implied above, I've been doing destructive testing of my joints. So far, with full surface bonding, I'm still using the same schedule of CF laminations on the joint. This ultimately produces a stronger joint, with a weight difference that is hard to measure. The goal, is to establish a joint that is as strong as a normal wet wrapped joint, but which has fewer laminations of CF and epoxy to save weight. When testing indicates that this is ready for market, I'll be sure to let you know.

In the mean time, I can miter and jig assemble my frames similar to steel frames, when these are set (and naturally in super alignment), I come back and vacuum one joint at a time - allowing for perfectly laminated joints.

Well, that's it for tonight. Gotta run, so we'll see you soon.

I've missed you guys

noreply@blogger.com (Rick Guggemos) — Sat, 24 May 2008 23:51:00 +0000

How ya'll doing?

I'm back, in more than one way. Time to resume blogging. And I'm getting over a bad bug that's laid me low for a week - but gives me some free time to post.

The winter was slow, as it was hard and long weather-wise. Next year will require some better solutions to keep the shop fit for working. As those get sorted out, I'll be sharing them with you.

Being a slow winter gave me the opportunity to do a few other things, some of which have be referenced in other posts. One we haven't discussed much is reflecting on frames and frame-building. All my thinking hasn't lead me to many firm, absolute conclusions. But it all helps me refine my thinking and goals. So I'm going to share some of these thoughts starting here with something about which I feel strongly.

It's not for me to tell other builders what to do, so let's be clear about this up front. But my belief is that too many custom builders are working too hard to be visually different, or even to create visual art rather than bikes. Each of us has a different approach to our visual aesthetic. Some work hard to achieve certain common elements throughout their work. Others strive to make each build unique. And all of this is good, from where I sit. But, when the decoration appears to somehow impede functionality - it disturbs me.

This year's Handmade Bike Show offered many examples. I don't really want to point fingers at anyone in particular - after all some of the worst examples come from very capable and successful builders. And some of these touches looked cool. But if you go to http://www.handmadebicycleshow.com/2008/, and look through the galleries, you can probably figure out I'm talking about. One bike, being shown for the second year in a row, isn't even ridable. Adding unnecessary, dysfunctional components or accessories, or significant (as in physically big, unnecessary, flashy) frame details aren't my piece of cake. Moreover, its likely to take buyers mind off of the more important aspects of bicycles and custom frame-building.

Richard Sachs probably represents the more Zen-like end of the scale. He's not into chrome or polished stainless. He works with a limited pallet of paint colors (or is that just his riders?), applied in traditional schemes. He doesn't do a lot of lug carving. But, he may put more than the average number of hours into a build - because he is obsessive about detail and functionality.

Farther down the scale are Curtlo's with their curved stays, or Kirk's Terraplane model with his curved stays. Without having ridden either, I'm comfortable conjecturing that these have no discernible performance effects. They do visually set these frames off, and don't impede the functionality of these frames. As such, they seem like fair approaches to incorporate style with functionality. Just like the Hetchin's curly frames that preceded them.

Personally I like a little flash in the form of polished stainless, and for dropouts, stainless is a functional improvement. Fancy paint is a cool thing, and long established as an aesthetic element of fine bikes. You, I and the next guy will have different opinions as to when these elements enhance or detract from the look of a bike - and I won't try to determine what other builders should do with these factors.

On the other hand, if you're building a fully equipped Rando bike, and can't fit the fenders concentric to the wheels, then who cares if you thread the dynamo wiring through the frame and rack tubes or not. And yet one respected name has advertising showing featuring such a bike. Schwinn (the real made in Chicago Schwinn) got this right, so top custom builders ought to as well.

Then there is the practice of penetrating tubes with tubes. The first time it looked kind of cool. And it probably didn't hurt too much other than to make the tube heavier (assuming the main tube itself wasn't very light,or that it had a very long butt). However, afterwards, repeating this practice is just derivative, non-functional, and a potential source of later problems for the rider. Some builders prefer to build exactly what the rider asks for - and if its pierced tubes, so be it - who can fault them for responding to their clients. But, the bike that Lance bought for his new store just wasn't likely to be ridden in any meaningful way, regardless of who purchased it.

I believe that all of this overlaps other behavior we see, such as the guys who buy a custom chopper and then trailer it to events. I just don't get this behavoir. If you're one of these guys, no problem - I'm not suggesting that you stop. But, it just doesn't make sense to me if either the rider or bike aren't up for the trip to the event - what are they good for? Showing off a fancy *purchased* chopper only says the rider was able to buy (finance?) the bike - it represents no skill in building, or aesthetic judgment, or riding ability. Look at me I have money?

The above isn't meant to pick on chopper guys, because this is just one example of a larger phenomena - that some frame-builders may have fallen into with their more outrageous designs.

The truth is that we live in a consumer society. Mere consumption doesn't ever satisfy anyone's needs. I can't prove this, and haven't done any scientific study of the issue. But, look around you and I think the statement proves itself.

If you doubt this, consider a few examples: We're drowning in the problem of too little oil. It doesn't matter if we're at peak oil of not. Prices around here are over $4/Gal. And most folks can't afford that - at least not without substantially changing their lifestyle. Should we be surprised about this turn of events when automotive sales for the last 10-15 years have returned to a focus on size of vehicle and amount of horsepower. No one needs 300-400 or more horsepower. No one can reasonably use that kind of power. Yet how many folks will stretch their budgets in order to have a huge powerful engine.

Yeah, we're putting a lot of emotional energy into our consumerism - trying to feel better, without consideration of functionality. And no, car sales aren't unique in this way. If they had any money left, American's would still be buying bigger and fancy houses - that they make less and less use thereof.

I'm a map freak - so Google Earth is just a great thing. It's interesting to look a rivers, lakes, and ocean front. Man, there's a lot of invested in boats, sitting in the water, with their covers buttoned up tight, doing nothing. Maybe the folks that take the pictures don't do so on weekends or holidays - but I bet even then, only a small fraction of the fleet is used on any weekend. This doesn't slow folks down from buying boats. And like cars and choppers, the bigger, fancier, and more powerful, the better.

It's long been said that the two best days for a boater are when he buys his boat and when he sells it. This suggests, awfully strongly, that the benefit of a boat is primarily the act of consumerism - and thereafter the best thing one can do clean their hands of their purchase. Now let's face it, there are folks who really use boats (and motorcycles/houses/cars). I'd suggest that in many cases, it is the owner of a small boat or a sailboat who is most likely to make significant use of their craft. There, the activities around using the boat are more accessible, and a source of enjoyment. When things get too fancy, boat ownership becomes just about posturing. And posturing isn't a very satisfying activity, if only because there's always someone who has more than you or I or the next person.

This probably sounds like a screed against consumerism - and likely it is. But, my point is that activity is where we find personal rewards. Hanging a bike on the wall doesn't really bring one much satisfaction. Riding a nice bike, properly fitted, is a joy. And by focusing too much on being visually different, IMO, some builders are helping push cycling too close to mass consumerism rather than pushing riders to be active.

Again, I'm not trying to bust anyone's chops here. But, this thinking does help me solidify the limits I impose on the builds that I do. Functionality has to be the driver for fine frame-building.

Hopefully I haven't PO'd all my readers. But, it is one of my convictions as a frame-builder - and I thought you should know.

Brief Update

noreply@blogger.com (Rick Guggemos) — Sun, 16 Mar 2008 14:40:00 +0000

Sorry I've been gone so long. Lots going on, and we'll be doing some catching. One thing is that I've developed a web store for bike parts that I like. Check it out at www.FixeesBikeShop.com

More soon,

Broken Record

noreply@blogger.com (Rick Guggemos) — Wed, 16 Jan 2008 01:01:00 +0000

Unfortunately work and weather has limited my shop time. No more work on chain stays or the Path Racer - no more pictures for the moment - sorry.

But, my new Sapim spokes came in and I was able to finish lacing and truing the light-rando wheels. They look pretty good. With the weight coming in so low, I'm considering using velo-plugs instead of rim tape. They're supposed to reduce weight a bit. But, I'm wondering if a light tape (not rim tape) might accomplish the same thing. The low pressure tires don't work so hard on the spoke holes, and the spokes are sized so that they don't stick out past the nipples. So, I guess that its time to experiment and weigh (literally) the options.

The other big news is Craig's List. I've been watching it and eBay looking for a lathe and a drill press - not thinking that I could possibly buy both. I have a small counter-top drill press, but it isn't heavy enough for the table to hold an angle while I miter a tube (using Joe Bringheli's miter jig). I know that the jig works, because I used one in his shop on one of his drill presses. So that's want #1. Everywhere I look, anything that looks adequate is outside of my budget, considering I can continue mitering with a hacksaw, grinder & files. But, I have a good space for it in the shop.

A lathe is a beautiful thing. That's a famous saying (started by Darrell Llewllyn - a great frame-builder in Australia). Ultimately, what we need is like a 12-13" swing and 24-30" between centers. This allows one to mount a fork, and cut the crown race seat on the lathe, which is more accurate than using a hand seat cutter. But that's just one thing the lathe can do. It can be used to cut miters, with the right fittings it can be used as a small milling machine, one can turn down tubes, and make a variety of parts and tools.

A big lathe like that needs a lot of space, often takes a 240v circuit or even 3 phase 240v - which would mean rewiring the shop and getting a whole new feed & panel installed for the house. It'd probably cost a grand for an old one with a little life left for frame building - but $3,000 would probably be a better amount to invest. And, it'd be hard to move around or ship. Right now, that's not in the cards for me.

However, somebody right here in town, had a 6" and a 9" lathe for sale on Craig's List. The first is a Sears/Dunlap, the second is a Central Machinery (Chinese - not the best brand of same, IMHO). The prices seemed attractive, so I called and visited 'Otto' (his Craigslist name). Otto takes me down to the basement, and it turns out that he likes to 'putter'. In his shop he has a beautiful Southbend Heavy 10. Very nice!!!! But, he has a variety of tools he's collected and tuned up - for sale. In fact, we haven't even made it down the stairs and he asks if I'm interested in a drill press?

Now, aside from not being able to fit or afford a big lathe, I have no experience with a metal lathe and will have to learn to use one. My first goal is to turn down (thin or reduce the gauge) some tubing - maybe 6" long. The small lathe is plenty big for that. Plus to learn on and make some small fittings, maybe even some tools etc.

It's got a new motor, probably over-powered by the size. The beds look nice, and there doesn't appear to be any lash in the cross slide. No center for the tailstock, but two sizes of jacobs chucks (one may work on the headstock). No face plate or 3 jaw chuck, but a nice 4 jaw chuck. Not a lot of change gears, but I can fill them out over time from eBay. A few other little bits and such. All tuned up, fresh paint, mounted on a nice board. It's low speed isn't very low, but I can probably come up with countershaft and slow it down a bit - plus with the small swing, the speed of the face is already sorta low. Small enough for the garage shop or basement. Asking $350 - let's me know it's negotiable.

So we talk, and look at stuff and I ask about the drill press. It's out in the garage, we go back up stairs and its tucked in tightly between a big Buick and the wall. It's from Taiwan. I don't recognize the brand (which is Taiwanese), but it's a nice, heavy sturdy piece of iron. Not new, but obviously well cared for. Looks like the best I could find for much under a Grand (I see a big jump up from what is available for $300 and what's available for a grand - lots in between with very incremental improvement - but I may be proved wrong). Anyhow, this looks very cool.

I ask him how much for both the lathe and the drill press, he thinks and says how about $300? I was figuring he'd want $500 or more and I'd be stuck. But... for this price, how can I go wrong? The drill press obviously won't fit in my car, but he has a mini-van. So tomorrow, I'll become the owner of a nice drill press and a good small engine lathe. How cool is that? Well, unless you're a bike building geek like me, it might not seem all that hot. But believe me, in my world, this is a grand slam. Yipee!

Anyhow, I'll be busy but try to keep you all updated and get the Path Racer pictures up here soon. Cheers

Brief Post

noreply@blogger.com (Rick Guggemos) — Tue, 08 Jan 2008 02:38:00 +0000

Only a little to report today. Yesterday I brazed the track forks to the stays and threw them into water to soak off the flux. The day job limited progress today, but I got the basement cleaned out, and reorganized, to prepare for doing carbon work inside (where its warm). Keep tuned for more info and related pictures of some test layups.

Speaking of warm, it hit 60 degrees farenheit yesterday, and today was darn close to that. Hard to believe it was 10 degrees only a few days ago, and I should make hay while the sun shines. Tomorrow looks to be another busy work day, but i hope to make it into the shop yet.

Meanwhile, my Grand Bois tires arrived, so it's time to finish the path racer and then get some pix of the completed bike. I have to say, the new Grand Bois look and feel the part of a fast, supple tire. Along with the 700Cx30s for the Path Racer, there is a pair of 650Bx32s for upcoming rando bike.

My next task is to clean up the chain stays, and some pix of same to share with you. From there, I have to miter the chainstays for Paul's bike, then set up the jig and tack it all together.
So with luck, we'll have some more pictures to view before the end of the week, then it'll be on to completing Paul's bike.

See ya soon

New Pictures

noreply@blogger.com (Rick Guggemos) — Sun, 06 Jan 2008 23:44:00 +0000

Vote on the right for your favorite frame material. BTW, hemp only works when its encased in epoxy (like carbon). :)

I've promised some pix from the build of Paul's new track bike. The tubing is SLX, which is like SL with reinforcing rifling in key joints. Below on the left is the end of the chain stays, and on the right is the bottom of the seat tube. In both pictures the rifling is pretty obvious. The yellow dust in the stays is paint from the hack saw blade, I took about a CM off of each end. The stays themselves are ROR (round/oval/round), so it shouldn't be necessary to crimp them to make room for the tire to fit. It is important, however, to position the forks so that the tire fits nicely in the ovalled rand for the stays across the full range of rear axle positions.

The bottom bracket shell is a Cinelli road shell with spoiler., If you enlarge the pictures and look closely, you'll see the filler in the cable tunnel. What you won't find is the casing stop that used to be their.

Next comes a rear and front view of the stainless fork crown. Originally the front had a flat land for the brake, like on the back. I'm almost finished rounding off the front, which I think will look better on a track crown. Then its the slow process of polishing the crown.

Finally you can see the the track fork being fit up to the chain stay. The fork has a bend in it near the end of the stay, so that the faces will be parallel. As a consequence, the inside miter is much shorter than the outside on. As you can see, the stays have a large overlap with the forks. In face, the overlap is more than an inch long. This probably isn't necessary, but on a track bike it's nice to make this intersection as rigid as possible.

At this point, I have one miter left to clean up. Then it'll be time to set up the jig, tack things in place, and get ready to braze this up. More pictures once we have more progress.

Pix?

noreply@blogger.com (Rick Guggemos) — Thu, 03 Jan 2008 23:37:00 +0000

Time is running out. Vote on the right for your preferred frame material!

It's 10 degrees Fahrenheit in the shop (garage) , so still no more work there and still none of the promised pictures. Instead, a few other pix and further discussion around building a light Rando bike. First a spy shot of the oh-so-close-to-done path racer. In the tradition of spy shoots, its dark, grainy and hard to make out. But, sharp eyed viewers will get a sense of how the finished product will look (as always, click to enlarge pix)
.
One Honjo is partially fitted and one to go. Tape and shellac the bars, replace the tires and change the chainring for a TA 1/8" track ring (although that Stronglight ring looks mighty pretty to my eyes).

I'm getting itchy to put this one on the road, but not until they're cleaned up a bit.

Next come some pictures of the wheels that I laced (not trued or tensioned yet) yesterday. More on that in yesterday's post.

The rims are made by Velocity, using the extrusion of the Aerohead. If you don't recognize the label, it's because the distribution rights to this rim (which is a 650B or 584 ERD size) belong to an Australian outfit called Chainring Transit Authority (or CTA). They fronted the money for having this size manufactured and got an exclusive on it. That said, their prices (even shipped from AUS) are quite fair, they offer extra services (want a hand polished rim? How about a customized drilling pattern?) and I enjoy doing business with them. Most likely, these rims will be the light-weight standard for 650B wheels for some time to come.

Here is the 100gm H2 front hub from White Industries. Lots of other hubs might have worked, but these combine lots of attributes that I like: finely polished; sexy shape (with a traditional look); nicely 'engraved' logo; nice sealed bearings, low weight, & made in the USA.

Here's the business end of the rear-hub. That's a titanium cassette carrier which helps the complete wheelset (using Sapim spokes w/ brass nipples) to weigh in at 1515gms. Not bad eh?

And if you break a spoke, any decent shop should be able to fix your wheel!

As is always the case, once you start weighing things in real life, they add up to more than theoretical weights. Also, at this point in the process I'm trying to be fairly conservative.

So let me explain theis chart. In the build kit, every item was weighed on a digital scale unless it is highlighted in yellow. We don't need the full length of the seat post and can probably get it down to its spec'd weight of 188 grams. Also, its easy to sub in a Sella Italia SLR for the Arione. This would net a reduction of about 0.2 pounds. But, in reality for a Rando bike, we might go with a Brooks saddle for an approximate weight gain of 0.7 pounds. And, I don't know what handlebar tape we'll use, or its weight.

However, the rider at hand likes the Arione so that's going to be the basis of our computation. The wheel weight is probably going to go down a little once the rear gets re-spoked - which should compensate for the h-bar tape. And who wants to cut seat-posts?

So the real open question is frame and fork weight. I may have under-estimated here, but don't think so. The fork will have relatively short legs and a rather short steerer, so I anticipate it coming in at around 700 grams if a fairly light crown is used. I don't think that it will be a problem to hit 700 grams. The frame itself has bigger question marks. First of all, let me note that the tube set weighed in right to the gram of the Columbus spec: 1420 grams. Using BikeCad, I determined the length of each tube, center to center, and created a ratio of that to the uncut tube length. So, if a tube, C to C, is 92% of its uncut length, then I multiply 92% times its weight. In reality, the tube weight should be less than this for two reasons: 1) the tube is butted, and all trimming comes off the much heavier ends; 2) the ends aren't cut square - they are mitered and really don't quite reach to center of a joint even at their longest point. So, my calculated final tube weight is probably well over the actual cut lengths.

This takes us from an uncut weight of 1420 grams to a cut weight of 987 grams. To this I've added the 108 gram raw weight of the rear dropouts and 132 gram raw lug weight. These will also be reduced, but not by much. In any case, the cut tubes, lugs and dropouts come to 1227 grams - well under the weight of just the uncut tubes. There will be a cable guide under the BB, some cable stops on the TT, a housing stop and a chain catcher on the chain stay, and a brake bridge. I've estimated these at 5 oz, bringing the total frame weight to 1369 grams. You might note that I haven't accounted for filler (silver) or paint. So I may have under estimated total weight. But then again, I've over estimated the tube, lug and dropout weight.

The net of this is that it looks like this bike, with 32mm tires will weigh about 16.75 pounds. I'd say not bad - but not a record holder. Also we have to mount a good front rack, a bag, fenders, and a light set. Ideally the light set will be generator based. So there is still work to do. But it looks like we're on the right track. And we aren't engaged in a weight contest, just trying to keep the bike as competitive as possible without compromising its performance. That's it for tonight.

Cheers,

It's late

noreply@blogger.com (Rick Guggemos) — Thu, 03 Jan 2008 05:46:00 +0000

It's late and I'm tired, so this will be short.

Laced up the wheels today. White Ind. H2 hubs, Velocity Arrowhead (w/ OC rear) 650B rims from CTA, Sapim 14/17ga 32x3-cross front, 14/15ga 32x3-cross rear.

I should note that I miscalculated the rear spokes and will be re-lacing with shorter spokes.

Anyway, the total weight of this wheel set (less rim tape and skewers) is 1515 grams. Not bad eh?

Good night