Shimano Xt Rd-m8100 Rd Shadow+ 12-speed Long For 51tThe Shimano Deore XT RD M8100 SGS rear derailleur provides fast and precise shifting operations over a wide gear range. Guide and tension pulleys with 13 teeth and a rubber damper reduce noise and increase ride comfort. They also improve the chain's grip under all conditions. Features: Faster and shockless shifting Low profile design Wide range 12 speed drivetrain with low sprocket combination 10 51T Decreased rear derailleur and chain tension in low