Designed for the next generation of drivetrains and the next generation of riders. The SRAM Force® XG-1270 cassette is optimized for electronic shifting and features Sram's X-Range™ gearing technology. Smooth, precise shifts.   Features At least five one-tooth jumps for a smoother gear progression. 10-tooth start helps provide a wider gearing range. Designed to work with an XDR™ driver body. MINI CLUSTER™ construction reduces weight and increases durability. Zipp wheels starting from 2012 are XDR™ compatible (freehub required).   Ratio