XD-15 Ceramic bearings provide superior smoothness, reduced weight and extended bearing life
A CN (tight clearance) upper pulley bearing maximizes shifting accuracy while a C4 (loose clearance) lower pulley bearing promotes unconstrained chain-line movement
AB0030: 12 tooth pulley set with 4mm upper & 5mm lower bolt-holes is designed as direct fit upgrade for SRAM 12 speed road and gravel derailleurs
AB0031: The eleven tooth upper and twelve tooth lower size and profile with 5mm bolt-holes are designed as an upgrade for most 11 speed Shimano GRX derailleurs
Lifetime warranty
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