How to choose your MTB bottom bracket?
The MTB bottom bracket is primarily designed to ensure the smoothest possible rotation for your crankset. This component must match the frame standard as well as the MTB crankset standard. Between frame standards and crankset standards, a little help is very welcome!
The standards
- Bearing quality: steel or ceramic
- Bottom bracket axle types: Hollowtech, GXP, BB30,...
- Bottom bracket shell types on the frame: BSC, Press-Fit,...
Bottom bracket types
Let us start with the simplest: bearing quality. Generally, manufacturers offer the same bottom bracket model in two versions: one with steel bearings; and the other with ceramic bearings. Ceramic has an unalterable surface that is harder than steel. The advantages are therefore as follows: a low friction coefficient and an increased service life without the need for maintenance. We should point out that this is only valid for 100% ceramic bearings, meaning both the balls and the races. However, the cost of the latter makes them reserved for experienced riders.
Regarding compatibility with the bottom bracket axle, it is worth knowing that, depending on the brand, various standards exist. To help you identify what you need, here is a list of the most common ones:
In the case where the bottom bracket axle is part of the bottom bracket:
- a Octalink 2nd version: cylindrical axle, 8 splines 9 mm long.
- b ISO Square Taper: tapered square axle, 12.5 mm at the axle end.
In the case where the bottom bracket axle is part of the MTB crankset, also known as a through-axle:
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Hollowtech II, X-type, Megaexo 24 mm diameter axle a. |
GXP 22 mm diameter axle on the left b1, 24 mm on the right b2. |
BB30 30 mm diameter axle c. |
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SRAM Dub 28.99 mm diameter axle c. |
PRAXIS M30 28 mm diameter axle on the left e1, 30 mm on the right e2. |
Compatibility with the MTB frame standard must also be checked. Here is some further guidance:
- BSC (also known as BSA): the internal diameter of the frame is 34.8 mm.
- Press-Fit: the internal diameter of the frame is 41 mm.
- BB30: the internal diameter of the frame is 42 mm.
- Press-Fit30: the internal diameter of the frame is 46 mm.
REMINDER: Some MTB frames in BSC format use an extended bottom bracket shell of 83 mm (instead of 73 mm) and therefore require a specific crankset axle.
On Fat Bikes, there are 2 bottom bracket shell length standards, at 100 mm (for a 170 mm wheel axle) and 120 mm (for a 190 mm wheel axle).
Which bottom bracket should you choose for your riding style?
When replacing a bottom bracket, you may not necessarily have a choice beyond the bearing quality. Indeed, the choice will depend on your frame standard and your crankset axle.
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MTB - Bottom Brackets and Bearings
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SRAM DUB BSA 73mm Bottom Bracket
Regular price 20,99 €Regular priceUnit price per -
SHIMANO XT SM-BB71-41A Press Fit 89.5/92mm Bottom Bracket
Regular price 13,64 €Regular priceUnit price per -
SRAM DUB PRESSFIT 89/92mm Bottom Bracket
Regular price 37,79 €Regular priceUnit price per -
Bottom Bracket SHIMANO MT501 BSA
Regular price 19,94 €Regular priceUnit price per -
SRAM DUB BSA 68/73 mm Bottom Bracket
Regular price 31,49 €Regular priceUnit price per -
RACE FACE CINCH BSA/BSC 30mm Axle 68/73mm Bottom Bracket
Regular price 36,74 €Regular priceUnit price per -
SRAM GXP TEAM BSA 68/73 mm Bottom Bracket
Regular price 31,49 €Regular priceUnit price per -
Bottom Bracket SHIMANO MT800 Press Fit 89.5/92mm
Regular price 26,24 €Regular priceUnit price per
