This Ultegra 6800 series 11-speed mechanical rear derailleur features Shimano's most refined mechanical design to date. Shimano derailleurs have also been known as a benchmark for clear, crisp and accurate shifting. The RD-6800 takes shifting quality to the next level with new pivot points that provide a lighter action or more clearly, less shifting force needed from your hands at the shift lever. Shifting effort is also more equal through the entire cassette for the same feel whatever cog you are in and the distance required to move the shift lever to change gears has been shortened.
Some of the more notable details of the 6800 rear derailleur has a low profile cable pinch bolt which has been repositioned for better leverage reducing shift lever pressure. Shimano claims improvements have also been made to maintain shifting precision over long term use. For the best shifting performance, Make sure you use Shimano's 11-speed specific low-friction derailleur cableset included with the shift levers. Most folks will want the SS version that works for up to a 28-tooth cog. Get the GS version if you plan on using a 32-tooth cog now or sometime in the future.
For 11-speed mechanical systems only. Maximum largest rear cog 28t for SS and 32t for the GS version