www.bmeres.com/bambooframe.htm
Bamboo MTB Frame (June 2004) This is my second home-made frame. This time I used bamboo rods connected with carbon composite joints. My Bamboo Frame I have seen many amazing constructions made of bamboo and I always wondered, why such light, strong, stiff and elastic material is not widespread used for building of bicycle frames. Since I finished my carbon frame, I was thinking about using bamboo for my second frame.
article describing a bamboo frame Craig Calfee built for himself a few years ago. My Bamboo Frame The most difficult part of building the frame was to find quality bamboo rods. I visited several dealers in near surroundings and I tried to find appropriate rods of the necessary diameters from huge amount of bamboo. Finally I found a few rods I wanted, but frankly said, next time I build such a frame, I'll rather grow my own bamboo or fly to Asia for it. The rods for the top tube, down tube and seat tube are some Chinese species of bamboo; The rods I selected for the seat and chain stay are some other species from Malaysia. I found also the appropriate thick-walled rods of another species for the seat stay. During breaking tests of these bamboo rods I found out that when I filled the inside with the polyurethane foam (which added only few gram of weight), the rigidity increased mainly of the rods for the seat and chain stay, which are the most critical parts of this frame. My Bamboo Frame The frame building itself was quite quick. I used the frame jig I made for my previous carbon frame. Bamboo rods were fitted in miter joints together with duralumin tubes (bottom bracket shell, head and short seat tube) and bonded with epoxy. The junctions in the rear part of the frame I made from polyurethane and the following laminating process of the joints with epoxy resin and woven carbon cloth was practically the same as for the carbon frame. Duralumin cable stops and brake bosses were made with water jet cutting and bonded to the carbon joints and secured with small screws. Finally the entire surface was covered with clear epoxy varnish. I made also one piece of my carbon saddle with the bamboo post, which was in the upper part (in the place of connecting with the adjustable saddle support) strengthened with the carbon composite. My Bamboo Frame In this picture you can see the bamboo frame together with the bamboo post and the carbon saddle. Update July 2005: Riding impressions - after one year When I built this bamboo frame, I was interested in how would it differ from my carbon frame. Above all I expected that thanks to the unique properties of bamboo, as a natural composite, the frame would be more able to absorb road shocks and the ride would be more comfortable. Now, after one year, I can write that the bamboo frame fulfilled all my expectations. Compared with the carbon frame it really does dampen vibrations better and the ride is more comfortable.
I found after one ride in May that the aluminum brake bosses at the seat stay, which were bonded to the carbon rings and secured with screws, became slightly loose. So, instead I made brand new carbon composite brake bosses, which now should withstand stress during braking. And besides, just to be sure I installed the carbon composite brakebooster that I made in the past to relieve the bamboo rods of the seat stay of stress. Repaired brake bosses The connections of the bamboo rods with the carbon joints are still rigid without any problems. I know I can expect the bamboo to shrink or split sooner or later, but I hope that thanks to the used method of securing the mutual connection between the bamboo rods and carbon joints it should not loosen in the case of shrinking and the splitting of bamboo can be easily repaired. I didn't heed advice that I should ride more carefully with this frame. But frankly, I still have some subconscious reactions to hear every unusual sound after strong bumps and inspect the frame after each ride. Nevertheless, I enjoy riding this bamboo bike more than the carbon one...
|
http://csua.com/feed/