Di2

Di2 is Shimano's electronic shifting system. Instead of cables, the shifters send electronic signals to derailleur motors that move the chain. The system is powered by a single internal battery, typically housed in the seatpost or frame.

Di2 offers more consistent shifts, the ability to shift under high load, and customisation through the E-Tube app. Modern Di2 systems are semi-wireless: the shifters communicate wirelessly with the derailleurs, while the derailleurs themselves are wired to the central battery.

See also: eTap, Groupset.