BMX Bottom Brackets

Make your BMX cranks feel smooth again with a new bottom bracket. 

Not sure what size bottom bracket (also known as BB) you need?

Refer to this size guide for help:

  • Mid bottom bracket: The most common in BB size, used in almost all modern BMX bikes. Bearings press straight into a frame with BB diameter of 41mm.
  • Spanish bottom bracket: Invented by Flybikes and found on some aftermarket frames sold around 2005 - 2013. Bearings press straight into a frame with BB diameter of 37mm 
  • USA bottom bracket: The bearings are housed in alloy cups, to suit a frame with a BB diameter of around 51mm (2 inches).
  • Euro bottom bracket: Small bearings are housed in threaded alloy cups, which screw into a frame with thread in the BB. BB diameter is 35mm.

Your crank spindle diameter determines bearing size and the most common sizes for freestyle BMX is 19mm, 22mm and 24mm. 

different size bmx bottom brackets