The Truvativ HammerSchmidt AM bottom bracket is a necessary piece of hardware to get your new HammerSchmidt crank up and running. Based on Truvativ's excellent Howitzer model, this bottom bracket uses custom double-row cartridge bearings for the ultimate in load capacity and dual-lip seals that keep dirt and water from ruining your fun.The Truvativ HammerSchmidt AM bottom bracket is available to fit 68/73mm or 83mm-wide bottom bracket shells and any/all applicable spacers are included. Please note that the bottom bracket must be used in conjunction with the respective HammerSchmidt crankset -- this AM bottom bracket features an M15 spindle designed for use with the HammerSchmidt AM Crankset. It installs with the standard external bearing bottom bracket tool. 199g.