Posted by AITA Ceramic on 27th Nov 2016

Bottom bracket types and standards

The bottom bracket on a bike connects the crankset (chainset) to the bike and allows the crankset to rotate freely. There are so many different types and standards of the bottom brackets in the market and we have summaries the most common ones for your reference.

Bottom Bracket Shell Thread Bottom Bracket Shell
Inside Diameter (ID)		 Bottom Bracket Shell
Width (W)		 Crank Compatibility
English Thread or BSA 1.37 in x 24 TPI 33.6-33.9 mm 68 mm Road
73 mm Oversize/MTB
83 mm Downhill/Freeride bikes
100 mm "Fat bikes"		 24mm Diameter Spindle
e.g. Shimano, FSA Mega Exo
Italian Thread 36 mm x 24 TPI 34.6-34.9 mm 70 mm 24mm Diameter Spindle
e.g. Shimano, FSA Mega Exo
BB30 (Cannondale) Press fit
not threaded		 42mm 68mm / 73mm (Road)
73mm (MTB)		 30mm Diameter Spindle
e.g. BB30 standard cranks
PressFit 30 (SRAM) Press fit
not threaded		 46mm 68mm / 73mm (Road)
73mm (MTB)		 30mm Diameter Spindle
e.g. BB30 standard cranks
PressFit 30 OSBB (Specialized) Press fit
not threaded		 46mm 62mm 30mm Diameter Spindle
e.g. BB30 standard cranks
BB90 Road / BB95 MTB
(Trek)		 Press fit
not threaded		 37mm 90mm (Road)
95mm (MTB)		 24mm Diameter Spindle
e.g. Shimano, FSA Mega Exo
BB65 (LOOK) Press fit
not threaded		 65mm 90mm 50mm Diameter Spindle
e.g. LOOK ZED
BBright Press fit
not threaded		 46mm 79mm 30mm Diameter Spindle
e.g. BBright standard cranks
BB86
(Shimano Press Fit)		 Press fit
not threaded		 41mm 86.5mm (road)
89.5mm or 92mm (MTB)		 24mm Diameter Spindle
e.g. Shimano, FSA Mega Exo
BB386EVO Press fit
not threaded		 46mm 86.5mm 30mm Diameter Spindle
e.g. EVO386 standard cranks