# Bamboo bike build. Step by step w/questions



## iwantalitebike (Jun 17, 2009)

Well..... Here goes. I'm starting my bamboo bike build. I built my jig a while ago. Ordered bamboo, carbon tow, epoxy and now here I sit. I started by cutting my Motobecane MTB apart. Here are a couple if pics of the progress. I will continue to update. Wish me luck.


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## AZ (Apr 14, 2009)

No pics.


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## iwantalitebike (Jun 17, 2009)

Tomorrow


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## iwantalitebike (Jun 17, 2009)

Here are some pics of the progress. On the seat tube, I drilled out the bamboo so that my seat tube from my old frame would fit inside. I used some liquid nails inside the tube and around the lip were the bamboo and tube meet. It seems to be very tight until i start rapping it with carbon. Any comments??


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## iwantalitebike (Jun 17, 2009)

Day 2. Just completed installing the down tube. Some tricky mitering, but I got it. Tomorrow; TOP TUBE!!


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## adarn (Aug 11, 2009)

I dig the bedrail(?) fixture!


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## Short Circuit (Nov 17, 2013)

The jig deserves a thread of it's own.

Mark


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## iwantalitebike (Jun 17, 2009)

The jig is made of UNI-STRUT brand metal. It's very versitle. Google it. It will surprise you.


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## iwantalitebike (Jun 17, 2009)

DAY 3. Top tube inplace. Drop outs mounted also. Looking like a frame now!


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## Drew Diller (Jan 4, 2010)

iwantalitebike said:


> The jig is made of UNI-STRUT brand metal. It's very versitle. Google it. It will surprise you.


I like that stuff. I use it to keep molds clamped shut.


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## iwantalitebike (Jun 17, 2009)

Here is tonight's progress!!


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## Short Circuit (Nov 17, 2013)

Looks good so far !!!!!

Mark


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## kosayno (Sep 7, 2006)

I may be wrong but it looks like the seatstays don't have enough tire clearance.


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## G-reg (Jan 12, 2004)

kosayno said:


> I may be wrong but it looks like the seatstays don't have enough tire clearance.


I thought that too looking at the rear triangle. "Dirt road" or CX bike perhaps? A composite outsider wonders about the various science/realities as it relates to corrosion with that many materials mixing.


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## iwantalitebike (Jun 17, 2009)

It's a CX frame. And as for the mixture of materials. We'll see how it goes!!


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## Drew Diller (Jan 4, 2010)

For the differing material mixture, if your aluminum gets insulated with glass or an initial epoxy layer that cures on its own and is secondarily bonded to (you'll want to etch the cured epoxy layer if you take that route), you'll be golden.

You might have enough room for CX tires. Be sure to mock up the chainring and crank - bamboo is a very uncooperative material in terms of chainstay yokes. Sure you could bend it, but you sure as sh!t cannot squish it as is done with metal.

Keep posting progress, shoot some close-ups!


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## iwantalitebike (Jun 17, 2009)

Here is the first layer. Kevlar cloth.


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## iwantalitebike (Jun 17, 2009)

Here is a Specialized Captain CX mounted to an old MTB wheel. Also putting layers on the joints now.


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## iwantalitebike (Jun 17, 2009)

Here is a pic of the seat post junction. It has about 5 layers in some spots. Also the other pic is the dropout area. Lower joints has only I layer of carbon and upper joint just the layer of Kevlar. I ran out of carbon tow so I will be on hiatus for. Few days. Feedback???


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## iwantalitebike (Jun 17, 2009)

Also, does anyone know where I could get canti bosses that would be good for wrapping in carbon?


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## Drew Diller (Jan 4, 2010)

Looking good so far. Are you keeping track of your carbon by weight? Layers is not so relevant because tow density can be different among rolls. Whatever you do make sure you get 120 grams of carbon or more at the head tube joint.

Nova Cycle Supply and Paragon Machine Works are places to get small hardware.

I'd say you could probably get away with just using 3M DP 420 and call it done, but that might be a bit ugly, and my inner Mr. Liability says yeah throw a bit of carbon on there after the bosses are tacked.


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## Drew Diller (Jan 4, 2010)

Also it is extremely difficult for me to tell given the compression wrapping direction - this is not unique to you, happens to everyone who uses tow... are you including tows that sort of run the length of the joint? The slippery epoxy and the nature of the winding wants to guide you into making sort of a chinese finger trap, which is great for compressive strength but isn't great for stiffness. One bike I made in this manner was a total noodle in part because of insufficient lengthwise tows.

A good example is for the bottom bracket, you want a good number of continuous fibers running from the rear of the chainstay yoke to the front of the down tube portion, sort of like a sling. Make sense?

Same goes for under the down tube in the head tube joint, which is even more difficult. The straight portions really want to run diagonal on you. Can be kind of maddening.


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## iwantalitebike (Jun 17, 2009)

Drew. I did run some tow length wise. I also did some unique patterns but all are underneath the layers you can see. I also plan to do another additional length patterns before the final wrappings.


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## kosayno (Sep 7, 2006)

The carbon wrap looks good so far. How many layers of kevlar do you have on the dropout joints? With carbon tow, it's fairly easy to get fibers crossing in different directions for strength at the ht, st and bb, not so much for the dropouts. It wants to run unidirectionally only. I usually wrap the dropout joints with at least 5 layers of carbon or kevlar cloth with at least another 4 layers of tow.


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## iwantalitebike (Jun 17, 2009)

Kosayno
I only put 1 layer of Kevlar on. But I will keep in mind to go all directions when wrapping. Thx.


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## kosayno (Sep 7, 2006)

iwantalitebike said:


> Kosayno
> I only put 1 layer of Kevlar on. But I will keep in mind to go all directions when wrapping. Thx.


I would've put more on the dropout joint since that epoxy gets very slippery and makes it near impossible to wrap any other direction other than across the tube. It's not too late and you could still do one of two things. First you could add more kevlar and wrap it with more tow or second, you can just add only more tow. If you only add more tow, before wrapping it, wait until the epoxy is near the end of its pot life and becomes really tacky so it doesn't slip. It's much easier to wrap it diagonally across the tube that way so you can go two directions.


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## iwantalitebike (Jun 17, 2009)

Here is the progress so far. I'm pretty close to completing the carbon wrapping.


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## iwantalitebike (Jun 17, 2009)

Has anyone has found a good canti stud mount and how to do it??


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## Weedling (Feb 28, 2008)

For the folks talking about the difficulty of aligning the fibers, when i made mine i made spiked ´dog collars´ out of nails and wrapped them around the bamboo near the end of the layup. This gave me a way of aligning loads of fibers lengthwise and diagonally by looping the fibers around the nails and back again. Hope that makes sense .....


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## Drew Diller (Jan 4, 2010)

Weedling said:


> For the folks talking about the difficulty of aligning the fibers, when i made mine i made spiked ´dog collars´ out of nails and wrapped them around the bamboo near the end of the layup. This gave me a way of aligning loads of fibers lengthwise and diagonally by looping the fibers around the nails and back again. Hope that makes sense .....


I had that _exact_ idea but never tried it! High five.


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## iwantalitebike (Jun 17, 2009)

I must be stupid. I don't get it. I need a pic.


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## Drew Diller (Jan 4, 2010)

iwantalitebike said:


> I must be stupid. I don't get it. I need a pic.


Yo, like this.

With tow and wet epoxy, in order to reverse direction at the termination of a lug edge, you have to rely on the meager amount of friction and viscosity present in the epoxy and carbon. So you get thick lumps at the edges of fiber that is mostly just going around the circumference of the bamboo et al.

If you could turn almost 180 degrees and follow the vector of the tube you're adhering to better, you'll have a stiffer, stronger lug.

I sketched this in like two minutes, so take it with a grain of salt.

EDIT: the main thing to consider here is, after you're done doing layup and the epoxy cures, you'd have to _carefully_ cut off the collar / anchor thing.


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## sean salach (Sep 15, 2007)

iwantalitebike said:


> Has anyone has found a good canti stud mount and how to do it??


Wouldn't something like this, cut out of a donor frame, work when wrapped sufficiently? You could even add a canti brace if you're worried about the bond.


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## iwantalitebike (Jun 17, 2009)

After a fairly long absence from the site. Here it is!!


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## TigWorld (Feb 8, 2010)

Weedling said:


> For the folks talking about the difficulty of aligning the fibers, when i made mine i made spiked ´dog collars´ out of nails and wrapped them around the bamboo near the end of the layup. This gave me a way of aligning loads of fibers lengthwise and diagonally by looping the fibers around the nails and back again. Hope that makes sense .....


What a great idea.


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## Drew Diller (Jan 4, 2010)

iwantalitebike said:


> View attachment 892160
> 
> After a fairly long absence from the site. Here it is!!


woot! The darker patches where you let the torch linger, I like that look.


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## Short Circuit (Nov 17, 2013)

That turned out awesome :thumbsup:

Congratulations on the build 

Mark


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## iwantalitebike (Jun 17, 2009)

Here is an update on the build. 

I got the bamboo rig up and running. And had absolutely no problems with anything. I have ride this about 8 times. Mainly on road but a couple dirt sessions. I copied the geometry from a Stevens size small frame. The specs called for a 70 deg head tube angle. My only complaint is the steering is very twitchy. Kinda like a typical 26er mtb. After doing some more research on other brands head tube angle. It seems to me that 71-72 deg is more common. I am thinking about redoing the head tube to correct the angle. Any thoughts??? Anyway...I rides awesome otherwise.


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## Short Circuit (Nov 17, 2013)

I would just leave it, ride it and get used the the way it handles unless you really feel uncomfortable with the way the steering is.

Mark


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## Drew Diller (Jan 4, 2010)

iwantalitebike, I'm sorry you're not smitten with the handling, but can you tell me, how do you feel about the high frequency damping of the bike? I find they do take the edge off the buzz while riding well worn pavement.


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## Eric Malcolm (Dec 18, 2011)

No, don't alter your H/T to a steeper 71-72* angle, you will make the situation worse.
The effect of such a change reduces your trail and this quickens the steering even more.
The picture of your bike indicates to me that you are a shorter legged rider with a longish back? There is a good amount of stem length and the forward stretch to the hoods have your hands well above the front axle, all those measurements slow the steering down. 

There is a world of difference between a 29'er and a CX bike so it does need adaption on your behalf, it's kind of like the difference between driving a SUV and a sports car.

To increase the trail as your bike now is, you would need to find a fork with less off-set.
This would slow down the twitchy feel.

Eric


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## Guglielmo (Feb 19, 2015)

*some weights and info*



iwantalitebike said:


> View attachment 892160
> 
> After a fairly long absence from the site. Here it is!!


Hi, how many grams of carbon fiber and of epoxy did you use for the frame joints? What brand of carbon tow?

Guglielmo


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