Here is a concept bike Hybrid² that demonstrates how riding a bike is not only  good for our health but also for our wallets and the environment. These bikes are specially built so that the energy used in riding it can get stored for further use. This stored energy eventually helps empower a complete  hybrid bus system.

The idea includes a public bike rental system near a hybrid bus depot so that people are able to access the bikes easily. After each use these bikes are then parked in the special bike stand and via certain mechanism the power of these very bikes are transferred to the hybrid bus system. So how does the user benefit other than the exercise? There is supposed to be a gadget in the parking unit that would allow users with their special ID card to get a credit on the power produced by riding bike. This credit would help them in getting a discount on the bus ride and if enough, the ride could be totally free. This concept is from Chiyu Chen.

[source: yankodesign.com]