I found this on the NYTimes chasing the new MIT wheel.  I think it appears destined for fixee style bikes, who else pedals backwards.  I might like one on my commuter though.

Superpedestrian, a start-up in Boston, announced on Monday that it has received $2.1 million in financing to help build a wheel that transforms some standard bicycles into hybrid e-bikes.

The product, the Copenhagen Wheel, is a design from the Massachusetts Institute of Technology SENSEable City Laboratory. The original goal of the wheel was to entice more people to more bicycles in large cities in lieu of cars by giving them help from a motor.

“If you think about today’s cities, they have been developed for the scale of the automobile, with people being required to travel great distances that are quiet large,” said Assaf Biderman, founder of Superpedestrian and associate director of the SENSEable City Lab. “Most cities are built around topographies that require motorized transport and it can make cycling and walking very difficult.”

Superpedestrian’s solution is to slip a motor into an existing analog product: the bicycle.

While the new wheel is still round, it has technology that makes it different from most normal bike wheels.

The Copenhagen Wheel replaces the rear wheel of a bicycle. It includes a motor powered by a built-in battery and sensors. When someone pedals with the new wheel in place, the bike uses sensors and an app on a smartphone to measure the amount of effort the rider is putting into each pedal. It then offers an additional boost when necessary.

One of the most interesting components of the new wheel is that the rider doesn’t need to tell the bike when help is necessary, the wheel just figures it out using the sensors and gives the bike a push.

“Riding on a flat surface, or up a hill, will feel exactly the same,” Mr. Biderman said.

The wheel doesn’t need to be charged or plugged in on a nightly basis, either. Instead, the wheel captures the energy from the brakes when a rider goes down hill and then stores that power in a high-capacity lithium battery. The motor also acts like a generator, creating power for later rides when the rider pedals in reverse.

The company said the wheel will last for 15 miles in each direction and will fit on most standard bicycles.

Superpedestrian is expected to start taking orders for the wheel next month and will begin shipping to customers at the start of next year.

The financing round is being led by Spark Capital with participation from David Karp, the founder of Tumblr.