This seems like such a good idea - cheap (well kind of!), effecient, green and pragmatic.  Though I have all sorts of nerdy questions about it - such as just how does the bottom bracket affix to the frame and how does it cope with the stresses placed upon it?

The bottom bracket (the axle for the pedals) is in steel - but joins two pieces of bamboo.  In a “traditional” bike it would be welded!

Blooming brilliant idea though!