Sunday, November 23, 2008

Cable Runs

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 op
ens 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. Th
is 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. Ea
ch 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 l
ayer 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 importan
t 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.


Friday, November 21, 2008

Done Baking

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 cosmet
ic 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 t
his 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

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.

Friday, October 24, 2008

CF Drop Outs


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.

Friday, September 05, 2008

Fabric Pictures

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 form
s. 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 v
ery 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 fabr
ic - 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 a
re 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.

Thursday, September 04, 2008

Carbon Pix

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 fiber
glass 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 t
hings 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 t
o 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.

Tuesday, July 29, 2008


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.


Thursday, July 10, 2008


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.


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!

Wednesday, July 02, 2008

What's new

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.

Saturday, June 14, 2008


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

Saturday, May 31, 2008

Carbon Carbon Everywhere

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.

Saturday, May 24, 2008

I've missed you guys

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, 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.