Data is transmitted by the sensors using low-power Bluetooth Smart technology, and is processed by an algorithm on the phone. It compares the rider’s current pedaling speed to their preferred cadence, then instructs the Di2 to shift up or down in order to restore or maintain that cadence.
Is this next years must have? I must admit there is an attraction to going auto. Forget gears and just pedal.
http://www.gizmag.com/automatic-gear-sh ... les/24956/