tech
Press-Fit Bottom Brackets
Press-fit bottom bracket shells are not threaded; instead the bearings or cups are pressed into the frame. This document details the critical factors that differentiate one press-fit standard from another. The table at the bottom of the page is useful for quick comparisons.
BB30
- Shell width will measure 68mm (road) or 73mm (mountain)
- Shell inner diameter (ID) will measure 42mm; BB30 bearings have a corresponding outer diameter (OD) of 42mm
- Bearings press directly into the frame and stop at removable snap rings; two snap ring grooves will be present inside the shell
- Designed for BB30 30mm spindle cranksets; adaptors are available that permit the use of 24mm spindle cranksets (i.e. Hollowtech II, GXP)
PressFit 30 (PF30)
- Shell width will measure 68mm (road) or 73mm (mountain)
- Shell ID will measure 46mm
- Both PressFit 30 and BB30 use the same 30mm ID bearings and 30mm spindle cranksets; the difference is that PF30 bearings are contained inside cups and the cups are pressed into the frame
- The shell will have a smooth bore (no snap ring grooves); the outer lip of the cup contacting the frame is what stops the press action
- Designed for BB30 30mm spindle cranksets; adaptors are available that permit the use of 24mm spindle cranksets (i.e. Hollowtech II, GXP)
BB86/92
- Shell width will measure 86.5mm (road) or 91.5mm (mountain)
- Shell ID will measure 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 spindle cranksets originally intended for external threaded cups (i.e. Hollowtech II, GXP)
BB90/95
- Currently used exclusively on Trek bicycles
- Shell width will measure 90.5mm (road) or 95.5mm (mountain)
- Shell ID will measure 37mm
- Bearings press directly into the frame and stop at an integrated raised step inside the shell bore; snap rings are not used
- Designed specifically for 24mm spindle cranksets originally intended for external threaded cups (i.e. Hollowtech II, GXP)
BBright Direct Fit
- Currently used exclusively on Cervelo bicycles
- Shell width will measure 79mm (road standard only)
- Shell ID will measure 42mm
- BBright Direct Fit is a variant of BB30 with an asymmetric wider shell (11mm offset to the non-drive side); bearings press directly into the frame and stop at removable snap rings.
- Accepts standard BB30 bearings but the wider shell requires a BBright-compatible crankset
BBright Press Fit
- Currently used exclusively on Cervelo bicycles
- Shell width will measure 79mm (road standard only)
- Shell ID will measure 46mm
- BBright Press Fit is a variant of PF30 with an asymmetric wider shell (11mm offset to the non-drive side); bearings are contained inside cups and the cups are pressed into the frame
- Accepts standard PF30 cups for but the wider shell requires a BBright-compatible crankset; adaptors are available that permit the use of 24mm spindle cranksets (i.e. Hollowtech II, GXP)
386 EVO
- Shell width will measure 86.5mm (road standard only)
- Shell ID will measure 46mm
- 386 EVO is a variant of PF30 with a wider shell; bearings are contained inside cups and the cups are pressed into the frame
- The shell will have a smooth bore (no snap ring grooves); the outer lip of the cup contacting the frame is what stops the press action
- Accepts standard PF30 bottom bracket cups but the wider shell requires a 386 EVO-compatible crankset
| Press-Fit Bottom Bracket Comparison | ||||||
|---|---|---|---|---|---|---|
| Type | Shell Width | Shell ID | Snap ring groove in shell? | Bearing or Cup? | Bearing ID | Seen on |
| BB30 | 68 or 73mm | 42mm | Yes | Bearing | 30mm | Various |
| PF30 | 68 or 73mm | 46mm | No | Cup | 30mm | Various |
| BB86/92 | 86.5 or 91.5mm | 41mm | No | Cup | 24mm | Various |
| BB90/95 | 90.5 or 95.5mm | 37mm | No | Bearing | 24mm | Trek |
| BBright Direct Fit | 79mm | 42mm | Yes | Bearing | 30mm | Cervelo |
| BBright Press Fit | 79mm | 46mm | No | Cup | 30mm | Cervelo |
| 386 EVO | 86.5mm | 46mm | No | Cup | 30mm | Various |