Shimano Ultegra Di2 RD-6870 Road Bike Rear Derailleur 11 Speed
Lighter and slimmer than its predecessor, the Shimano Ultegra Di2 RD-6870-SS Rear Derailleur now features an automatic protection system that moves the cage out of harm's way in the event of a crash. It'll even automatically realign itself with the cassette following an impact. Simply press and hold the shift button and the rear derailleur will go all the way up and down the cassette. When programmed at the E-TUBE platform, you can customize how many gear changes a press and hold actuates. Choose from five shifting speeds, ranging from very slow to very fast. Di2 electronic system guarantees easier, effortless, faster and more precise gear changes in demanding conditions.