Mtb 30mm stainless bottom bracket our threaded 30mm bottom bracket shares the same high quality design and durability as our well proven 24mm version external bottom bracket designed for threaded bottom brackets the machined aluminium cups hold stainless steel cartridge bearings in stainless races high quality stainless steel bearings give a much greater life span than stock units cartridge bearings are replaceable the unit is suitable for 68 73 83 100 and 120mm width bottom brackets designe