For use with Shimano 11 Speed STI levers on Shimano 11 Speed equipped Ultegra and 105 Road Bikes. Now with 2x11-speed compatibility and technology borrowed from Dura-Ace, the Shimano 105 RD-5800-GS Rear Derailleur has a new spring mechanism and cable pitch that provides "robust adjustability" for perfect alignment.
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-5800 an equal, positive sensation regardless of the direction of your shift, or the size of the sprocket that you're shifting to. Super crisp and professional, there's no more feeling like shifting down is such a slog. The 105 5800 Rear Derailleur reduces shifting effort in the lever, shift accuracy improved by the redesigned spring. You'll find your shifting experience with the 105 5800 groupset on par with Ultegra, Dura-Ace and Di2 systems. GS version is a medium cage (longest cage of the two models available) This Shimano 105 rear derailleur is compatible with a 32T cassette.