The Senseable City Laboratory at M.I.T. has designed a wheel that captures the kinetic energy released when a rider brakes and saves it for when the rider needs a boost.  The new wheel uses a kinetic energy recovery system, the same technology used by hybrid cars, like the Toyota Prius, to harvest otherwise wasted energy when a cyclist brakes or speeds down a hill. With that energy, it charges up a battery inside the wheel’s hub.  Copenhagen

The sleek red hub, called the Copenhagen Wheel, can be retrofitted to any bike’s rear wheel, and it includes sensors that track air quality, a meter that logs miles and a GPS unit to track routes. All that data can be sent via Bluetooth to a rider’s smartphone and shared with others. This eliminates the clunkiness of other electric bikes with heavy batteries and unwieldy wires by placing all the technology into the wheel.

Another group back at M.I.T. is building a different electric bike wheel. It‘s designed to be plugged in to charge, and may add regenerative components as an external accessory, but not as a component embedded into the wheel’s hub.

It could be great for people who have a 10-mile commute and don’t want to show up at work sweating.
Elderly bikers might also make a good target. For my mother it would be perfect. She loves riding her bike and has one or two hills on her normal route that this could help with.