SRAM Force 1 Mountain Bicycle Rear Derailleur - 00.7518.072 A dedicated 1x rear derailleur. Exact Actuation for fast and accurate shifts using SRAM's 1:1 actuation ratio X-SYNC pulley features a 12-tooth design that helps control the chain's lateral movement. CAGE LOCK technology makes for fast wheel changes or chain installation. ROLLER BEARING CLUTCH's one-way roller clutch controls chain tension for consistent shifting.