Why Bamboo ?
Mainly, because it's got style. Because it is perfectly suitable as a building material for bike frames and because it is sustainable.
Bamboo is a natural fibre material. Other technical fibres are ie glass fibre, carbon fibre or steel concrete. Fibre materials consist of highly stable fibre, which is embedded in within a stabilising mass, the matrix. In the case of carbon fibre compounds this is carbon fibre and epoxi gum. In the case of bamboo it is the main fibre embedded in the base bamboo tissue. Therefore bamboo is a natural light weight building material.
The relation of bamboos elasticity to density is very similar to that of aluminium. A bamboo frame therefore weigths the same as an aluminium frame, have the same bending stiffness, whereas the torsion stiffness compared to aluminium is less, which provides better flexibility when riding in an upright position (uphill).
Bamboo consits of an extremly hard surface, harder than most other woods. The surface will get very few scratches or cranks.
For those of you who are interested in the mechanical porperties of bamboo, here's a good overview done by the RWTH-Aachen (only in german :(
A little history in between
Bamboo has been used to build bike for more than 100 years. It has been a massively used light weight building material, mainly in Asia. It is not very surprising, that bike frames have been made of bamboo in some asian countries. But even in the US bike builders experimented with bamboo end of the 19th century.
The common ground on all of this historical experiments is that the bamboo frame has always been a product of small businesses or craftsman, bike lovers obviously. There was no big scale industrial production of bamboo frames.Bildquelle: Wikipedia. An American bike from 1896. The frame made of bamboo. Exhibited in Prague's Technical Museum.