And buy several boxes of surgical gloves.
Composite bikes are not built of bamboo, carbon fiber, hemp, or whatever.
They are made of rubber gloves.

I was thinking it would be great to make a version that did not use the hazardous resins and CF.
What are your thoughts on this: http://www.suscomp.com/index.htm
and TY for the search term I found hemp: http://www.hemptraders.com/product_i...roducts_id=176

Never had any experience with it, so I can't answer.

Wow you guys are real troopers. All the bamboo bikes look great as is. Has someone tried the split and reglue bamboo lengths yet?

Yep. Haven't used it in a bike yet though.

http://www.bikeforums.net/showthread...1#post11146457

So I made a blog for bamboo bikes and other projects (link in signature). If anyone would like the ability to post on my blog, let me know and I will add you. Here is a picture of my third frame:

http://1.bp.blogspot.com/_-bwKM_iTlr...0/IMG_0342.JPG

I have a writeup on my website I can send you the code for if you want other people's methods:

http://build-its.blogspot.com/2010/0...ike-frame.html

Yeah, please do send it. :)

Do you want me to send you a PM with the HTML code, or add me as a contributor? Either one works for me.

You can just send me the code. I don't want you to waste time editing it if it doesn't look right. I can also add you as a contributor if you want.

Um, I can't respond to your PM because I don't have enough posts. I have only added authors to my blog by using their email address. I'm not sure how to do it by looking at your profile. Is there a way to do it through your blog or something?

^^^
Go say hello to 12 people in introductions and Bob's your Uncle.

I gave my bamboo frame the ultimate test by riding the 100k D2R2 this summer. The ride was over hilly terrain on some very rough dirt roads. The bike survived without any damage but the stiff frame really put a hurt on my body! I have since concerted the bike to single speed status for use this comming winter on the bike paths. http://bikeforums.net/attachment.php...hmentid=172338

Awesome blog

I am thinking about building a bamboo tandem. Any thoughts on boom tube size? I was thinking 2" then 1 1/4" for the rest.

THE BAMBOO CYCLE INTRODUCTION: We again make our bow to the public and present our [Catalogue for the Season of 1897[/COLOR]. It is our good fortune on this occasion to acknowledge for the past year a record of trading that has thoroughly and permanently established the reputation of "Bamboo Cycles," and created a demand for manufactures that has at times strained the utmost capacity for our Factories to supply. This gratifying result has, we venture to assert, been solely attained by absolute sheer merit. Practical demonstration and not theoretical assertion has been the keystone to our efforts, and the success achieved warrants the assumption, to use a homely colloquialism, that the "Bamboo Cycle" has "come home to stay." It is our boast, that our patrons will find in our machines, the essentials to comfort, elegance and reliability, and we invite all lovers of the wheel to visit our City Showrooms, and there inspect our improved models for the coming season. Click for larger image of joints The construction of our machines consists principally of three materials, viz.: Bamboo, Aluminium and Steel, by which combination we claim to have perfected a cycle that in strength, lightness, life and durability must render it more popular than ever ; while for ease and comfort in riding, absence of vibration, and artistic beauty of appearance, it has no successful rival in the whole of the Cycle World. ref: Bamboo Cycle Co. Ltd. Catalogue p.2 [1897].

TESTIMONIALS from 1896

I don't know anything about tandems....is the boom tube the one that goes from bottom bracket to bottom bracket?

If you look at my bike above, I used 2" poles for the main triangle. Tubes that are only 1 1/4" in diameter might be too small which could cause your frame to flex. If your frame flexes too much, it will likely break at some point. I would probably go for something closer to 1 1/2" and maybe slightly larger.

The BBs is 68mm so I would not want to go over 2.25" (57mm) so that would be 5mm on each side for joints. The Boom tube is the one between BBs there will be 3 diagonal tubes like this: http://www.bikejournal.com/images/Be...JY10%20002.jpg

However, the top tube on mine will have a sharper angle to allow the stoker to be short as in 7-year-old size.
Like this with the 3rd tube:
http://www.circlecitybicycles.com/gifs/cm-peri.gif

I am also planning on hemp for the joints to be as eco as possible. It seems to come in two sizes .5 and 1.0 mm which should I get?

You probably won't need to use anything larger than 2". You might need larger tubes on a tandem though, I'm not too sure. :/

It probably doesn't matter either way. If you get .5 it will probably take a little bit longer to put on because it's smaller, but might look a little bit better because it will probably leave smaller gaps.

Do you have a tandem frame to cut up or at least model your bike after? If you've never made a frame before, I would recommend cutting the tubes out one, or maybe two at a time and replacing them with bamboo.

What kind of wrapping pattern do you use with the tow? I will be using hemp (.5mm) and really don't know how many layers to put on. Guess I will do a bunch of test joints. I am hoping to learn to do my lashing like this that you can see through the resin.
http://www.khm.uio.no/utstillinger2/...kkerfisk_2.jpg

With carbon tow I mainly wrap the carbon around in whatever way is convenient. However, I think that the carbon fiber needs to have tow going perpendicular to it to hold the strands together. So I will cut a few shorter pieces and put them on two different poles in a way that would normally be hard to wrap. It's sort of difficult to explain . . . I will try to get pictures later if I can.

The Calfee bamboo bikes have hemp lugs. It looks like he just wraps it around and then sands them down a lot.

http://www.calfeedesign.com/bamboo.htm

I have heard (read) that bamboo and aluminum are pretty similar in strength properties. I have an aluminum tandem. The boom tube is at least 2.5". Maybe you could get away with smaller if you never have another adult ride with you. Then again, plenty of people make ersatz tandems by doing the cut and shut on two single bikes. No oversized boom tubes there. In the end, the real problem might be our (I include myself) wanting our bamboo creations to look like the steel and/or aluminum creations we know and love. Maybe we should be working outside the box? Paralleled tubes? Bamboo plywood sheets? Recumbents? FWIW

An update about my frame:
The frame rides great so far, but I have had some issues. First of all, my dad took it on a test ride without asking me, and heard a crack while riding up a steep hill. Neither the bamboo or carbon joints broke- what happened was that the bond between the bottom bracket lug and the downtube failed, so the tube could slide in and out of the lug. Apparently the epoxy did not bond properly to the bamboo. I fixed this by drilling a hole through the lug and bamboo, glueing a hardwood dowel into the hole, and wrapping the joint in carbon fiber another 2.5" up the tube. I made sure to rough up the surface much better than before using my dremel. Before, the bamboo was just sanded. So far it works great, and I have really mashed it without problems.

Second problem just happened this afternoon, conveniently right before I was leaving for Critical Mass. I jerked my shifter harder than I should have, to switch from the highest to lowest gear, and popped the cable stop off the top of the downtube. I temporarily fixed it with some gorilla tape, but I will wrap the stop in carbon later.

It's sort of hard to tell from your pictures, did you put some carbon fiber along the grain of the bamboo? I've had some problems when I only wrap it around the circumference of the pole.

Also, my fourth frame. The green stuff is tape:

http://4.bp.blogspot.com/_-bwKM_iTlr...0/IMG_0413.JPG

Yes, I wrapped in both directions. I alternated every other layer.

The skin of bamboo contains silica and is too smooth for epoxy to adhere.
It needs to be sanded down all the way.

I sanded the ends of my tubes before I tacked my frames together but I did not where the braze-ons mounted. I had trouble with them popping loose on my first frame.

I sanded well below the outer layer. That is why the bamboo is golden colored. When I first heat treated it, it was dark brown

Gotcha.
Maybe try misting or wiping the sanded ends down with a damp towel to open the pores of the bamboo to facilitate the epoxy penetration.

That or cut light threads in it with your dremmel.

That's basically what I ended up doing when I fixed the downtube joint.

The very outermost layer on the bamboo is sorta waxy, get rid of that and the epoxy adheres fine. Silica is the favorite thixatropic element for a lot of admixtures to epoxy.