GreenWheel is an all-in-one electric powered wheel being tested by MIT scientists.  It contains the motor, battery and electronics all inside the hub, with only the throttle having to be mounted on the bicycle’s frame.
They’re designing it to work with any bike frame with no modifications, and the unit cost is targeted at a couple hundred dollars, making it hundreds of dollars less than competing electric bike mod kits.
The unit will give a typical bike a range of about 25 miles of pedal-free power, or double that if the rider pedals.  It can be recharged via pedaling or plugging it in.  The GreenWheel is also durable. The team estimates its range at 40,000 miles, or about eight years work of travel at an estimated 20 miles per business day.
“You’ll have to replace the bike before you replace the batteries,” Lin told Discovery News.
