The praxis m30 bottom bracket 6873mm the m30 bottom bracket allows us to use one spindle for three of the most common bottom bracket frame standards in the market the m30 bottom bracket is available as english threaded frames bb86bb92 or in the very popular praxis conversion for bb30 or pf30 frames this design keeps the cartridge bearings outboard the frame free of frame tolerance issues and keeps the bearings aligned for longer wear and noise free riding one crank with proper bott