The GreenWheel bicycle wheel features an electric motor and batteries in a small built-in housing. The GreenWheel can be retrofitted to any bike. It uses a bluetooth connection that communicates throttling instructions to the device when the rider twists the throttle handle.
Charging the wheel can be accomplished by plugging in or by pedaling. The motor has a range of roughly 25 miles when fully charged. Lithium ion batteries are used in the GreenWheel rather than the heavier and more environmentally destructive lead-based batteries used in some other pedal-to-electric bicycle conversions. The unit is also completely self-contained: no need to install a separate battery pack.
Ryan Chin and Michael Chia-Lian Lin developed the Greenwheel as part of MIT’s Smart Cities programs.
The video shows an alternate conversion system.