Ross Millar writes in about Marco Facciola’s completely functional and completely wooden bicycle. Marco writes:

I was mostly concerned that the wooden chain would break. I researched the strength of different types of wood and built jigs to test the stresses that each of the chain’s components would undergo during use. First, I used my weight (150 lbs) to see if the wood could endure this amount of force. Then, my father would stand on the jig. I calculated that my dad’s weight would be twice the force each chain component would need to withstand. I made the specs high to ensure the chain and sprockets would work even if the wood had imperfections. During testing, I made adjustments to the chain’s components, and once I had it figured out, I realized that completing the project was within my grasp.

Wooden bicycle – Link.