Shimano Deore XT WH-M8100-B Complete Replacement Freehub Body Y0HH98030Shimano Deore XT WH M8100 B Complete Replacement Freehub Body MICRO SPLINE freehub technology was first introduced with 12 speed XTR mountain bike drivetrains in 2018 and has been utilized throughout Shimanos premium mountain bike range since. Now, MICRO SPLINE has trickled into gravel with Shimanos 1x12 speed GRX gravel groupsets. MICRO SPLINE accommodates the wider gear ranges of 1x12 speed setups including a 10 51 tooth cassette. With this setup,