Shimano Ultegra RD-6870 Di2 Short Cage Rear Derailleur

When you've got something good, why not share it? The Shimano Ultegra FD-6870 Di2 Electronic 11 speed rear derailleur has received several of the new technologies that Shimano has packed into the Dura-Ace 9080 Di2 rear derailleur. To give you top performance, Shimano has redesigned this rear derailleur to give you a tap-of-the-button functionality. What this means is that you'll no longer have to worry about whether your derailleur is in the correct gear, because the system will do it all for you. Forget about having to futz with trimming and cable tension, this derailleur is smart enough to do all that for you. What this means is that you can focus your efforts entirely on racing, and no longer have to devote anything to how your drivetrain is shifting. Short cages can handle up to a 28 tooth cog.