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#5, almost alive
For people who've joined since spring 2012, I'll give you a quick summary so this post doesn't leave you entirely scratching your head: I'm an amateur, hobbyist frame builder. Materials of choice are bamboo and carbon fiber. I made the world's first bamboo fat bike, because... well, because. Here's take one and take two, my second and fourth frames, respectively.
Based on conversations during ride stops around local trails, and how much I enjoy some parts of the build process, I feel encouraged to try my hand at building custom frames for profit.
But there's a long way to go. The major gripes I have at the moment are front triangle stiffness and lug cosmetics. So far, I've constructed my own carbon fiber head tubes with a 49.57mm ID. That accommodates a big old headset, and very large diameter bamboo poles. This greatly mimics Boo Bicycles designs. So far I have ridiculously underestimated just how stout the down tube of a bike frame needs to be.
I have big ambitions, but I've learned to take things one step at a time. One reason that it is taking so much time is that I wanted to avoid using Kickstarter et al. I think what I want is within my grasp if I simply bide my time, and buy equipment that I want piecemeal... I'll have almost all the stuff that I would have received all at once from a Kickstarter. This way, I'll appreciate what I've earned, as opposed to feeling guilty about having things provided to me in addition to suddenly having tools, with pressure to perform, yet little to no practice using said tools.
So, I haven't built a frame in the entirety of the summer. LAME. But I'm getting close to being equipped the way I want.
The current step foward: evaluate a different method of carbon layup, for both increased stiffness and cleaner appearance. I'm trying out unidirectional prepreg carbon. This refers to carbon fiber that is delivered with epoxy already infused in the fibers, to a very precise ratio. The cure time is heat activated. This means either that the prepreg must be stored frozen and then heated to a relatively low temperature, or for other formulas, stored at room temperature and then heated to a very high temperature. The unidirectional means that each ply has fibers running in one direction, and I have to arrange layers of plies in a variety of directions to handle a variety of forces.
Pros:
- Less waste epoxy, and less cleaning.
- Extremely wide pot life (amount of time you have to work with the carbon before the epoxy gels and starts to set). Weeks, in my case. This makes it easy to quit on time for the night so as to not burn myself out.
- Tacks onto the mold well once placed, and stays there.
Cons:
- Addition of cooling and heating elements for storage and curing can be (and were, for me) additional costs. Cheap, visually beaten up high efficiency freezer was obtained at ApplianceSmart and doubles as some food storage.
- Bamboo doesn't much care for direct, localized infra red light. Learned this the hard way. Water loss and internal air pressure changes need to be accounted for.
- Use of heat reduces my selection of binding and filling materials.
Interestingly, every carbon fiber professional I've talked to personally eschews the use of prepreg. But the big manufacturers use it almost exclusively. So: evaluate for myself.
Enough words, I'm almost done with #5. Here's a teaser, below. The top layer of carbon is sacrificial, this is before compaction and curing, which is why one ply insisted on slipping off in the picture, as it was 20F in my garage at the time, which reduces the tack of the prepreg to almost nothing.
The frame I'm building is my take on a Surly Long Haul Trucker, but with 40mm rims and Maxxis Hookworms.
Sadly, very little work happens in my kitchen anymore.
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Hooozaaah!
Let me be the first. You are one kool dood, my friend, for you jump in while others simply sit and dream!
Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
- John Hajny, a.k.a. TrailMaker
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Oh, and one note on the blatant ripoff of Trucker geometry. Did you know that Hookworms on wide rims are almost the exact same circumference as 700x25C tires?
Aww yeah. Cush and roll.
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Forced out into the garage huh?
Cool, room for a kegerator then!
Looks really schmooooooth from what I can see. Can't wait to see the rest of it!
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Looking awesome... Be watching this one. Drew, what's the chance of building a boo/carbon frame that can take the knard/rabbithole and use a 73 bb shell a la the Krampus? Run it SS or 1x9. Possible? Inquiring minds (i.e. potential future customers) want to know...
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Thanks for the write-up, glad to see thing progressing. Keep us posted with new pics please 
"No one's interested in something you didn't do."
FREE BEER! (tomorrow)
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subscribed  always awesome stuff from Drew
No matter how slow you ride, you're faster than anyone sitting online whining about slow riders.
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 Originally Posted by montana_ben
Looking awesome... Be watching this one. Drew, what's the chance of building a boo/carbon frame that can take the knard/rabbithole and use a 73 bb shell a la the Krampus? Run it SS or 1x9. Possible? Inquiring minds (i.e. potential future customers) want to know...
The name I've settled on marketing will - jokingly - imply what kinds of bikes I want to make.
One of the thing that generally depresses me about life is limitation. I want to remove as much of it as possible. But, in some hypothetical situation where I actually sell frames (whereupon I would be paying for ads on this site), I also have to balance fantasy with practicality.
Short answer, if you need a Krampus now, buy a Krampus. If you need a Krampus in general, buy a Krampus. I rode one exactly a mile and a half and was all I waaaaant oooooone the entire way.
I wanted to show something amazing at NAHBS 2013, but that will not happen in time.
Practically speaking, a bamboo Knard capable frame would likely have all carbon chain stays. One design challenge of bamboo frames is the relatively large diameter bamboo poles necessary for rear triangle stoutness. In close quarters situations with fat tires, by the time you've cleared the cranks, there's very little bamboo left in the picture, so in some cases, why bother...
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Originally Posted by sasquatch rides a SS
subscribed always awesome stuff from Drew
^^What he said^^ 
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Very cool, Drew! Looking forward to seeing it in person. It's gonna be cool...
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Can't wait to see more
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Twenty2 Cycles
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Practically speaking, a bamboo Knard capable frame would likely have all carbon chain stays. One design challenge of bamboo frames is the relatively large diameter bamboo poles necessary for rear triangle stoutness. In close quarters situations with fat tires, by the time you've cleared the cranks, there's very little bamboo left in the picture, so in some cases, why bother...
That's what I was wondering about, thanks for answering...
Totally get what you're saying about 'hypothetically', business-wise. But figured it's nice to have a certain confidence and drive to go forward on different builds and designs that's based on people expressing their interest as potential customers, down the trail as it were. Cool to watch your refinements and progress from build to build!
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mtbr member
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Very Nice !
Hi, I'm one of those newcomers your referring to..... And I am Impressed! Very nice work.. I will be watching your progress with great interest. And now, back out to the shop..... I got my own little somethin I'm workin on too... Keep up the awesome work !
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Originally Posted by Drew Diller
...Practically speaking, a bamboo Knard capable frame would likely have all carbon chain stays...
Good to see another design from you, Drew.
Sadly one of the things I have noticed about bamboo framed bikes evolution, is that as the design progresses, the lugs get longer and longer until there's hardly any bamboo.
You're well on your way to a full carbon bike though
As little bike as possible, as silent as possible.
Latitude: 57º36' Highlands, Scotland
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Awesome work so far
What's the color difference between the seat tube and the rear stays? Are they different species or cured differently? Sorry if im missing something from one of your last posts.
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Originally Posted by AC/BC
Awesome work so far
What's the color difference between the seat tube and the rear stays? Are they different species or cured differently? Sorry if im missing something from one of your last posts.
Different species. I didn't specify, so you're not crazy.
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Originally Posted by Velobike
Sadly one of the things I have noticed about bamboo framed bikes evolution, is that as the design progresses, the lugs get longer and longer until there's hardly any bamboo.
Agreed. That's basically what I wanted to try: a bamboo bike with ultra short, old school lugged road frame joint appearance.
But, how to do that in a structurally sound way, and not using the bamboo as simply a veneer... it is an unproven idea, one I want to try. A master wood worker could probably do it, but the extra difficult part with bamboo is that it isn't strong from the inside out. It is strong from the outside in. If I were to put a lug on the inside, I'd still have to reinforce at least *some* of the outside. So I don't think you'll ever reach the point where two bamboo poles would be mitered together and that's it. But I'd like to get close to it.
Ironically, it would probably only bolster the number of people who insist, to my face, that my frame has been painted to look like bamboo. One guy really got on my nerves late this summer where I almost lost my tact, what, do you want me to cut it open so I can satisfy your skeptical mind? I didn't let that spill out of my mouth thankfully.
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Outstanding! I find the lugs are so much easier to finish when using carbon fabric vs. tow.
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Drew, I've been hanging out on this forum for over a year, but have somehow just now tapped into your awesome madness. So thanks for the history and context. And the great writing and pics. Totally digging this thread.
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Not terrible. I see where my mistakes were with giving the bag room to walk in some spots. The concave radius above and to the front of the BB shell, as well as the top of each chain stay. The top layer or two of fiber was pulled along forcefully where the bag was left to stretch the most.
Genuinely surprised by the amount of epoxy that was actually squeezed out. Still, much cleaner.
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ZOIKS;
How much cleaner is that than your previous tow & goo efforts, eh? How much less finish work required?! With more advantageous resin-to-fiber ratios, how much stronger and stiffer too?! Hopefully not so stiff that it stresses the bamboo too much....
as always.
Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
- John Hajny, a.k.a. TrailMaker
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