CAMPAGNOLO RD20 S RECORD 12s 34tOptimised spring return On rough roads, the spring positioned between the upper body and the pivot absorbs the vibrations, ensuring the chain always rest properly on the sprockets 12 tooth jockey wheel on the rocker arm, perfect for use with cassettes that have a wide range of teeth and ensures constant chain tension Removable pivot is compatible with hanger mount and direct mount style frames Compatible with spacing and axle types commonly associated