Shimano Dura Ace SM-EW79A-E Electric Wire
Shimano Dura Ace Di2 SM-EW79A-E Electrical Wire is required to ensure that the signal goes from the shifter to the derailleurs. The reliability of the electric cable has been proven by repeated field tests in various riding conditions, including extreme temperatures, rain, mud, and cobble stone roads.
Adding electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching - which are commonly found when using traditional mechanical cables - but also provides effortless gear shifts. Dura-Ace Di2 requires two cables: a handlebar cable set to connect the shifters to a battery indicator junction box or FlightDeck, and the other to connect the handlebar cable to the battery and derailleurs.