This seems cool and fun, and potentially a great engineering exercise. That is, you have to build around the properties of your material. But from an environmen

This seems cool and fun, and potentially a great engineering exercise. That is, you have to build around the properties of your material. But from an environmental and economic perspective I am deeply unconvinced. A simple but well made and well maintained bicycle can be quite cheap and perform extremely efficiently for decades. I used to fix bikes and old Raliegh three speeds were just the most amazing machines I've ever dealt with. Replace the rubber parts, true the wheels, and tighten the brakes and they are good to go again... thirty or forty years after they rolled off the assembly line. That is efficient.