just came across a short movie on the internet (it's not in english). it's about a man that has a passion for building wood models and he actually had constructed a wooden bike (the ratchet mechanism in the casette, the wheels and spokes). he even at one point said that he would construct a wooden chain and guess what....he did..... . the only thing that he couldn't build out of wood were the tires

http://www.trilulilu.ro/ellissei/d8030572ff5b40

sorry if my english is sloppy (I'm not a english speaker)