SRAM's X9 Rear Derailleur is favored by everyone from weekend rippers to marathon riders crossing the Alps. It offers a great balance of durability, low weight and slick shifting. To achieve that, the X9 features an aluminum/composite construction, SRAM's 1:1 actuation ratio and direct cable routing for quick, reliable shifts. The incredible roller bearing clutch keeps chain slap and derailleur bouncing at bay. Plus, this beauty is built to last so you can shred singletrack for years to come.