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PF30 vs BB30: the difference explained
PF30 and BB30 share a 30 mm crank spindle and the same bearing size, so the cranks are interchangeable, but the frames are built completely differently and that is where the confusion and the creaks come from.
The shared part: a 30 mm spindle
Both PF30 and BB30 were designed around a 30 mm aluminium crank spindle running on 6806 bearings with a 42 mm outer diameter. That is why a BB30 crank and a PF30 crank of the same brand use the same spindle and are, at the crank level, the same part. The difference is entirely in how the frame holds those bearings.
Because the spindle and bearing are shared, moving a 30 mm crank between a BB30 frame and a PF30 frame is a matter of changing the bottom bracket, not the crank.
BB30: bearings press into the bare frame
A BB30 shell is 42 mm in internal diameter and 68 mm wide on road frames or 73 mm on mountain frames. The 6806 bearings press directly into the aluminium shell against a pair of retaining circlips. There are no cups. This keeps the system light and lets the frame use a wide, stiff shell, but it also means the bearing seat is the frame itself, so a shell machined slightly out of tolerance can leave the bearing loose, which is the classic BB30 creak.
Because the bearing sits directly in the frame, a worn or noisy BB30 is often fixed by moving to a pressfit cup system such as a thread-together bottom bracket that takes the frame tolerance out of the equation.
PF30: bearings press into cups, cups press into the frame
A PF30 shell is wider in the bore, 46 mm, and 68 mm road or 73 mm mountain wide. The 6806 bearings are held in nylon or alloy cups, and it is the cups that press into the 46 mm shell. The extra 4 mm of bore over BB30 is what makes room for the cup wall.
Putting the bearing in a cup rather than the bare frame gives a more forgiving, quieter interface, which is why many creak fixes for 30 mm systems end up as a PF30 thread-together bottom bracket.
Which one is your frame
Measure the bore. A smooth 42 mm bore with circlip grooves and bearings sitting straight in the metal is BB30. A smooth 46 mm bore that takes pressed cups is PF30. The shell width, 68 or 73 mm, tells you road or mountain. Confirm both numbers before buying, because a 30 mm crank will physically fit either frame only with the matching bottom bracket.
| Standard | Shell bore | Bearing | Bearing sits in | Spindle |
|---|---|---|---|---|
| BB30 | 42 mm | 6806 (42 mm OD) | the bare frame, on circlips | 30 mm |
| PF30 | 46 mm | 6806 (42 mm OD) | pressed cups | 30 mm |
Figures from Park Tool and Wheels Manufacturing bottom bracket references.
Fitting a 30 mm crank, or swapping to Shimano or SRAM?
Open the BB compatibility toolPick your shell and crank spindle to see the exact bottom bracket you need.Find PF30 BB30 bottom bracket on eBayaffiliateRelated
Sources: Park Tool: Bottom Bracket Standards · Wheels Manufacturing bottom bracket fitment reference · Bottom bracket (Wikipedia, CC BY-SA)