Shimano Ultegra 6800 11 Speed Rear Derailleur;

Shimano's Ultegra 6800 Rear Derailleur got some serious upgrades from the 6700 series. It's more compact, lightweight, and features consistent shifting across the cassette's whole 11-speed range--a welcome improvement. A redesigned spring mechanism gives the RD-6800 an equal, positive sensation regardless of the direction of your shift, or the size of the sprocket that you're shifting to. There's no more feeling like shifting down is such a slog. The Ultegra 6800 Rear Derailleur reduces shifting effort in the lever, connected by Shimano's proprietary, polymer-coated shift cable. The cable knocks out unnecessary mechanical drag and ups the shift accuracy improved by the redesigned spring. You'll find your shifting experience with the Ultegra 6800 groupset on par with Dura-Ace and Di2 systems.