OSBB bottom bracket
OSBB is a press-fit standard: the bottom bracket shell is smooth on the inside. You recognise an OSBB frame by a shell 61 mm wide with an inner diameter of 46 mm.
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Sizes of a OSBB bottom bracket shell
61 mm
Shell width
46 mm
Inner diameter
smooth, no thread
Inside of the shell
Frequently asked questions
Which cranksets fit?
CEMA has OSBB bottom brackets for Shimano and SRAM GXP cranksets.
How do I know for sure my frame is OSBB?
Measure the bottom bracket shell: on OSBB it is 61 mm wide, with an inner diameter of 46 mm.
What is the difference between OSBB and PF30?
An OSBB shell is 61 mm wide, with an inner diameter of 46 mm. A PF30 shell is 68 or 73 mm wide, with an inner diameter of 46 mm. More about PF30 →
Still not sure?
The bottom bracket finder takes you to the bottom bracket that fits your frame in a few questions.
Go to the bottom bracket finder