Bottom Bracket Standards


Finding the correct bottom bracket for your frame can be challenging. To accurately determine the bottom bracket standard in your frame, it is best that you remove your crankset, and any installed bottom bracket cups or bearings. Then measure both the inner diameter and width of your frame's bottom bracket shell.

The chart below lists most of the current bottom bracket standards found on today's frames. Once you determine your bottom bracket standard, you then need to Identify Your Crankset.

BB Standard

Frame BB Shell
Inner Diameter

Common Shell Width

Frame BB
Shell Threaded?

Also Known As

Notes

Wheels Mfg Bottom Brackets

BSA Threaded
  • 1.37 in x 24 TPI
  • 33.6mm - 33.9mm
  • 68mm (road)
  • 73mm (mountain)
  • 83mm (Downhill)
  • 100MM (Fat Bike)
  • Yes
  • Standard Threaded
  • English Threaded

Most common threaded BB shell system.

  • 1.37 in x 24 TPI
  • Left hand thread on drive-side
  • Right hand thread on non-drive
TREK BB90
  • 37mm
  • 90.5mm
  • No
  Trek direct-fit system. Bearings are pressed directly into frame.
TREK BB95
  • 37mm
  • 95.5
  • No
  Trek direct-fit system. Bearings are pressed directly into frame.
BB86 / BB92
  • 41mm
  • 86.5mm
  • 90mm
  • 91.5mm
  • 104.5mm
  • 107mm (DH / Mountain)
  • 121mm (Fat Bike)
  • 132mm (Fat Bike)
  • No
  • PF24 (Chris King)
  • PF41 (Hope)
  • PF86
  • PF90 (Trek)
  • BB107/PF107
  • BB121
  • BB132

Designed to be used with 24mm spindle diameter cranks (Shimano HollowTech II), hence the PF24 designation.

Some brands call this PF41, describing the frame shell diameter instead of the crank spindle diameter.

Removable bottom bracket cups.

BB30
  • 42mm
  • 68mm (road)
  • 73mm (mountain)
  • 84.5mm (Specialized MTB Alloy OSBB)
  • No
  •  Specialized Alloy OSBB

6806 bearings are pressed directly into the frame.

May use removable c-clips as bearing stops, or the bottom bracket shell may have molded or machined bearing stops.

BBRight (Direct Fit)
  • 42mm
  • 79mm
  • No
 

Cervelo R5ca Frames only. BB shell is 11mm wider on the non-drive side.

6806 bearings are pressed directly into the frame.

Specialized OSBB Alloy
  • 42mm
  • 68mm (Road)
  • 84.5mm (Mountain)
  • No
 

Same as BB30.

6806 bearings are pressed directly into the frame.

Cannondale BB30a
  • 42mm
  • 73mm
  • No
 

BB shell is 5mm wider on the non-drive side.

6806 bearings are pressed directly into the frame.

PF30
  • 46mm
  • 61mm (Specialized OSBB/FACT)
  • 68mm (Road)
  • 73mm (Mountain)
  • 83mm (Downhill)
  • 100MM (Fat Bike)
  • No
  • PressFit-30

Removable bottom bracket cups.

BBRight (Press Fit)
  • 46mm
  • 79mm
  • No
 

Cervelo Frames except R5ca. Also used by 3T.

Removable BB cups.

BB shell is 11mm wider on the non-drive side.

Specialized OSBB Carbon (Road)
  • 46mm
  • 61mm (Road)
  • No
 

Specialized carbon road frames with 61mm wide shells for use with Specialized FACT cranks.

Removable BB cups.

Cannondale PF30a
  • 46mm
  • 73mm
  • No
 

Similar to PF30, but asymetrical BB shell is 5mm wider on the non-drive side.

Removable BB cups.

Cannondale Asymmetric Integration (Ai)
  • 46mm
  • 83mm
  •  No
 

Cannondale Asymmetric Integration (Ai) found on Scalpel-Si and F-Si System frames. BB shell is 83mm wide, but symetrical

Removable BB cups.

T47
  • M47 x 1 Threaded
  • approx. 46mm ID
  • 68mm
  • 73mm
  • 83mm
  • 100mm
  • Yes
  • Threadfit 30i

Frame's bottom bracket shell is threaded with M47 x 1 threads.

  • Left hand threads on the drive-side
  • Right hand threads on the non-drive.
386EVO*
  • 46mm
  • 86mm
  • No
 

* Essentially a PF30 with 86mm wide shell.

392EVO*
  • 46mm
  • 92mm
  • No
 

* Essentially a PF30 with 92mm wide shell.

Colnago ThreadFit82.5
  • 41mm
  • 86.5mm
  • Yes*

* Colnago standard with a threaded BB shell. Aluminum cups are threaded into the frame that result in the BB86 standard (41mm ID x 86.5mm width).

Wheels Mfg does not make the threaded cups for these frames. Visit excelsports.com for cups
Look BB95
  • 65mm
  • 90mm
  • No

Unique to Look frames. Requires bearings and hardware from Look

  • Wheels Mfg does not offer any compatible bottom brackets for Italian threaded frames.
Wilier BB94
  • 37mm
  • 93mm
  • No
  • BB93

Unique to Wilier. Bearings press directly into the frame. Similar to Trek BB90

Truvativ ISIS Overdrive
  • M48 x 1.5 Threaded
  • 68mm - 100mm
  • Yes

Little used threaded BB shell standard. Usually found on Cyclops indoor bikes. *NOT COMPATIBLE WITH T47*

  • Wheels Mfg does not offer any compatible bottom brackets for Italian threaded frames.
Italian
  • 36mm X 24tpi
  • 70mm
  • Yes

  • Wheels Mfg does not offer any compatible bottom brackets for Italian threaded frames.

 

Notes:

To accurately identify your frame's BB shell, always measure the ID and width. Or, have a professional bike mechanic do the work for you.

  • Press-Fit refers to aluminum or plastic bottom bracket cups, which are pressed into the frame. The bearings are then pressed into the cups.
  • Direct-Fit refers to individual bearings pressed directly into the frame with no removeable BB cups.