PiCycles™ are set-up to be inline hybrids. It has power on both wheels with human providing the energy in the rear, and the electric motor powering the front. Keeping the drive systems completely separate means no problematic gear meshing. It also means you can operate it as a bicycle, as a motorcycle, or seamlessly combine both human and electric power to reach the perfect speed while still burning some calories but without breaking a sweat.
This link is worth looking at :
Iphone Compatible controlled by its own app.