Identifying a Press-Fit Frame
A press-fit frame is identified using two measurements:
• The width of the bottom bracket shell
• The internal diameter of the bottom bracket shell
Measure the bare frame only. Do not include any installed cups, spacers, bearings or seals.
Common Press-Fit Frame Standards
BB30
BB30 frames use a 42 mm internal shell diameter.
Typical shell widths:
• Road: 68 mm
• Mountain bike: 73 mm
In the original BB30 system, bearings with a 42 mm outside diameter and 30 mm inside diameter are pressed directly into the frame. The standard was introduced by Cannondale and was later adopted by several other manufacturers.
BB30 frames were designed around 30 mm crank spindles, although suitable adapters or conversion bottom brackets can make other crank standards compatible.
BB30A
BB30A is an asymmetric road standard with:
• 73 mm shell width
• 42 mm internal diameter
The system is closely related to BB30, but the shell is 5 mm wider and extends further on the non-drive side. Because of this asymmetric design, a standard BB30 bottom bracket should not automatically be assumed to fit a BB30A frame.
PF30
PressFit 30, commonly known as PF30, uses:
• Road shell width: 68 mm
• Mountain bike shell width: 73 mm
• Internal shell diameter: 46 mm
Unlike BB30, where the bearings sit directly in the frame, PF30 bearings are fitted into cups that are then pressed into the shell.
PF30 was developed for 30 mm crank spindles, but the larger 46 mm shell diameter gives manufacturers more flexibility when producing bottom brackets for other crank standards.
PF30A
PF30A is an asymmetric road standard with:
• 73 mm shell width
• 46 mm internal diameter
Like BB30A, the PF30A shell is 5 mm wider than the conventional version and is asymmetric on the non-drive side.
BB86 and BB92
BB86 and BB92 share a 41 mm internal shell diameter.
Typical widths are:
• BB86 road: 86.5 mm
• BB92 mountain bike: 92 mm
This family of press-fit standards was originally developed around 24 mm crank spindles and has been used extensively across road and mountain bikes.
You may encounter BB86 or BB92 on bikes from brands such as Giant, Canyon, BMC and Cube. It remains one of the more widely recognised press-fit systems in the cycling industry.
BB89
BB89 is primarily found on some older mountain bikes.
Its dimensions are:
• 89.5 mm shell width
• 41 mm internal diameter
It is closely related to the BB86 and BB92 family but should be identified by its specific shell width.
BB386
BB386, often called BB386EVO, combines a wider shell with a larger internal diameter:
• 86.5 mm shell width
• 46 mm internal diameter
The standard effectively combines the width of a BB86 road shell with the larger bore associated with PF30. This allows the frame to accommodate a broad range of crank and bearing configurations when the correct bottom bracket is used.
BB90 and BB95
BB90 and BB95 use a relatively small 37 mm internal shell diameter.
Typical widths are:
• BB90 road: 90.5 mm
• BB95 mountain bike: 95 mm
These standards were developed by Trek. The bearings are pressed directly into the frame rather than sitting inside separate cups.
Because of the limited internal shell diameter, BB90 and BB95 frames are generally intended for 24 mm crank spindles, including compatible Shimano and SRAM GXP configurations.
OSBB
A genuine Specialized OSBB road frame typically measures:
• 61 mm shell width
• 46 mm internal diameter
The term OSBB has not always been used consistently, so do not rely on the name alone. Some frames identified as OSBB may correspond dimensionally with another standard, including BB30 or PF30.
Carefully measuring the actual shell is the safest way to confirm compatibility.
BBright42
BBright42 is a road standard with:
• 79 mm shell width
• 42 mm internal diameter
The bearings are fitted directly into the frame, similar in principle to BB30.
BBright46
BBright46 also uses a 79 mm shell width, but the internal diameter increases to 46 mm.
The larger diameter allows the bearings to be installed in press-fit cups.
The BBright system was developed by Cervélo to support a wider, asymmetric frame design. The drive side retains a width similar to a conventional 68 mm BB30 or PF30 shell, while the non-drive side extends by an additional 11 mm.
The key difference between the two BBright versions is the shell diameter:
• BBright42: 42 mm direct-fit shell
• BBright46: 46 mm press-fit shell
Because both versions are 79 mm wide, measuring the internal diameter is essential.