2 Things that make me worry (Score 1)

Alright first off, I really do trust the strength of bamboo and its general ability to not snap in half. My problem is that the bar that goes from the handle bars to the rear axle only appears to be on one side, that really doesn't seem to structurally sound, I'd make two bars like that one and cross them to opposite sides of the rear axle underneath the crossbar. And the other thing, I really hope bamboo doesn't swell with water, otherwise the thing could work great one day, then the next after a rainy night all the bamboo would be rattliing in those sockets. Not sure if thats a problem with bamboo but it's something to look into. On a little side note, I would never ride this thing. It looks like an easy way to see how good bamboo can pinch skin. (Note the point where the cross bar intersects the bar running from the handle bars to the rear axle)