WALGUN threaded BSA 22mm 24mm ceramic bottom bracket-BSA24 BSA22 is made of 6805 sealed ceramic bearings and 7075 aluminum alloy (full CNC machining). The inch thread is suitable for 22mm and 24mm shaft diameter cranks (shimano ultegra, sram gxp xt, etc.) ). BSA24 is suitable for 68mm road bikes and also compatible with 73mm mountain bikes.