It is called "Copenhagen Wheel" Developed by researchers at the Massachusetts Institute of Technology's SENSEable City Lab. it is installed in the rear hub of a bike wheel. It is equipped with a proprietary computer, batteries and sensors which monitor the rider on how hard he pedals, if the rider is having a dificulty pedaling the motor will activate to give support and help you conserve energy.
"The motor integrates itself with the rider's motion very, very seamlessly," said Assaf Biderman, co-inventor of the device. He added, "The combination of power from the Copenhagen Wheel and the cyclist's energy can make an average biker move "almost like a Tour-de-France-level athlete in your daily commute,"
The Copenhagen Wheel can make the bike travel as fast as 37.28 mph. The device is expected to cost at around US$690.
Motor US: 350W / EU: 250W
SIZE: 26" or 700c rim
BATTERY: Removable 48 Volt Lithium
BATTERY LIFE: 1000 cycles
CHARGE TIME: 4 hours
TOP SPEED: US: 20 mph / EU: 25 km/h
RANGE: Up to 50 km / 31 mi
WEIGHT: 5.9 kg / 13 lbs
CONNECTIVITY: Bluetooth 4.0
SMARTPHONE OS: iOS, Android
COMPATIBILITY: Single Speed or 9/10 Speed Free Hub
BRAKE TYPE: Rim brake and regenerative braking (downhill and back-pedal)
DROPOUT: 120 mm (single speed) 135 mm (single speed and multi-speed)