No kidding, there actually are bicycles made of sustainable materials. Take Calfee Design's bicycle frame made of bamboo tubes mitered together and bound by epoxy soaked hemp fiber.
Following an interview with the frame’s new owner, the company hand selects a bamboo tube set that will deliver characteristics consistent with the rider's requirements. Each bamboo frame requires more than 40 hours of labor to build. Every frame is made to order and every frame is unique. It's also made in the U.S.A.
The bike’s not cheap, though. It costs $5,245 with a 10-year warranty. But it sure is cheaper than a car.