Press-fit: the pressed-in bottom bracket, explained
Press-fit is the family of bottom brackets in which the bearings or their cups are pressed into the frame, with no thread. It's not a single standard: the shell can be 41 mm (BB86/BB92), 42 mm (BB30) or 46 mm (PF30). It's lighter and stiffer than threaded, but the one that tends to creak, and it installs with a bearing press, not a hammer.
When someone says their bottom bracket is "press-fit", they're only telling you the family, not the standard. What matters is the shell diameter: 41, 42 or 46 mm. That's where BB30, PF30, BB86 and BB92 come from.
What is it?
In a press-fit bottom bracket there's no thread: the bearing (or a cup holding it) is pressed into the frame and held by friction. This allows wider, lighter carbon shells, but it depends on very tight tolerances: if the frame is a few hundredths off, the bottom bracket moves and creaks.
Specification
What you need to know
Don't mix press-fit standards blindly: a 41 mm shell is not the same as 42 or 46. Each diameter needs its own bottom bracket and often its own tool. If yours creaks, it's almost always fixed by cleaning, greasing the interface and reseating it properly, not replacing it.
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Frequently asked questions
Is press-fit the same as PF30?
No. Press-fit is the family; PF30 is one specific standard within it, with a 46 mm shell.
Why do press-fit bottom brackets creak?
Because they rely on very tight tolerances: if the frame is a few hundredths off, the cup moves under pedaling and makes noise.
Can it be installed with a hammer?
No. You must use a bearing press; a hammer permanently deforms the frame shell.