The Shimano Dura-Ace Di2 Complete Wire/Power Kit contains all the necessary pieces to connect their Dura-Ace Di2 components on your bike. This kit includes both front and rear wire kits, battery, charger, and power cable. You'll not have to search far and wide to gather the necessary items and hope that you've got what you need to make it all match together on your bike.

As we've taken care of the parts assemblage for you, all you'll need to do is measure your bike to determine which length rear (lower) harness you'll need to fit your bike. To determine the best size external harness for your bike, Shimano recommends measuring from the bottom of the bottom bracket shell to the back of the bottom of the head tube. Call this measurement "B." Then measure from that same point on the bottom of the head tube to the bottom of the handlebar next to the stem. Call this measurement "A." Add A+B-30 to get X, the size needed. The Small is 770mm long and handles measurements from 650-770mm. The Medium is 830mm long and can handle measurements from 710-830mm. The Large measures 890mm in length and can take care of measurements from 770-890mm. If you have a bike that's designed to have an internal wire through the down tube and have the battery mounted under the bottom bracket, select the Short Cradle version. Likewise, if your bike frame is Di2 specific and built for the wires to run completely inside the frame, select the Internal version. Both the Short Cradle and Internal harnesses will accommodate the largest frame sizes.

The Dura-Ace Di2 Complete Wire/Power Kit also offers another option -- Road Bike or TT Bike. The Road version is designed to be used with Shimano's Dura-Ace Dual Control levers, and the TT version is intended for their Dura-Ace Tri/TT shifters with the multiple shifting options.