BB30A bottom bracket
BB30A is a press-fit standard: the bottom bracket shell is smooth on the inside. You recognise a BB30A frame by a shell 73 mm wide with an inner diameter of 42 mm and an asymmetric shell design. Although 73 mm is usually associated with MTB frames, BB30A is used mainly on road bikes and certain gravel bikes.
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Sizes of a BB30A bottom bracket shell
73 mm
Shell width
42 mm
Inner diameter
smooth, no thread
Inside of the shell
Frequently asked questions
CEMA has BB30A bottom brackets for Shimano and SRAM GXP cranksets.
Measure the bottom bracket shell: on BB30A it is 73 mm wide, with an inner diameter of 42 mm.
A BB30A shell is 73 mm wide, with an inner diameter of 42 mm, and is asymmetric on the non-drive side. Although 73 mm is usually associated with MTB frames, BB30A is used mainly on road bikes and certain gravel bikes. A BB30 shell is 68 or 73 mm wide, with an inner diameter of 42 mm. More about BB30 →
A BB30A shell is 73 mm wide, with an inner diameter of 42 mm. A PF30A shell is 73 mm wide, with an inner diameter of 46 mm. More about PF30A →
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