Fatbike Bottom Bracket Tech Info

PF41 Fatbike BB

Wheels Mfg Fat Bike PF41 bottom brackets are manufactured to the current PF41 standard, and are for use in bottom bracket shells that are 121mm. Our bottom bracket consists of two machined cups with sealed bearings pressed in. The female threaded cup is press-fit tolerance, and is pressed in to the frame using a bearing press with our BB86/92 Cup Drift. The male threaded cup is inserted by hand in the opposite side, threaded into the other cup and tightened down. This system secures the bottom bracket in the frame, eliminating loose and noisy bottom brackets.

  • Shell Width: 121mm
  • Shell ID: 41mm
  • Bearings are contained inside cups which are pressed into the frame; shell has a stepped design but there are no snap ring grooves
  • Designed specifically for 24mm (Shimano, FSA, etc.) and 24/22mm (SRAM, Truvativ, etc.) spindle cranksets originally intended for external threaded cups.

PF41 Fat Bike Bottom Brackets


Fat Bike BB Tech Links

PF30 Fatbike BB

Wheels Mfg Fat Bike PF30 bottom brackets are for use in bottom bracket shells with a 46mm ID and 100mm wide. Our bottom bracket consists of two machined cups with sealed bearings pressed in. The female threaded cup is press-fit tolerance, and is pressed in to the frame using a bearing press with our PF30-OB Cup Drift. The male threaded cup is inserted by hand in the opposite side, threaded into the other cup and tightened down. This system secures the bottom bracket in the frame, eliminating loose and noisy bottom brackets.

Note: Some cranks designed for 100mm BB shell widths and external bearings may not work, or may require additional spacers.*

  • Shell Width: 100mm
  • Shell ID: 46mm
  • Bearings are contained inside cups which are pressed into the frame

 PF30 Fat Bike Bottom Brackets


* Check Your Fat Bike Crank / BB Compatibility

Our PF30-FAT bottom brackets are designed to replace similar PF30 bottom brackets. They are not a direct replacement for PF30 bottom brackets with external bearings. If you are replacing your PF30 bottom bracket with a Wheels Mfg PF30-FAT bottom bracket, you must make sure there is enough bearing contact surface on your crank's spindle to interface with the bearings in the BB cups. There are a few fat bike cranks that are designed for PF30 bottom brackets with external bearings. These systems have an overall frame + bottom bracket width of 121mm, and may not have bearing surfaces in the correct location to work with Wheels Mfg PF30-FAT bottom brackets.

 

Wheels Mfg PF30-FAT overall bearing widths:

PF30-FAT Bearing Width 

You should be able to see the bearing surface on your crank spindle as a slightly raised diameter:

 Crank bearing surfaces

 

If the bearing surfaces on your crank are not wide enough to allow for proper bearing to spindle interface, our PF30-FAT bottom bracket will not work. This may be the case for wide fat bike cranks with spindle lengths of 170mm and above. Please take careful measurements before ordering.

Improper crank/bearing interface