Shimano Ultegra Di2 EW-SD50 Electric Wire
To outfit your Ultegra 6770, Ultegra 6870, or Dura-Ace 9070 Di2 bike, you will need five wire sections: front wire harness, down tube, front derailleur, rear derailleur, and battery. The front wire harness is sold separately, and is the only section that comes in just one length. Each of the remaining sections is available in three lengths--small, medium, and large. Refer to the size chart for available lengths, categorized by section. One nice thing about the E-Tube system is that all the wires are the same, save for the length. This means that all the connections are identical, and it doesn't matter if your frame has internal or external routing. Confused about how to build your Di2 Kit? Read our Learn Article.