Shimano XTR SM-BB91-42A Hollowtech II Pressfit 42 X 84.5mm MTB Bottom Bracket BB 

Vendor: Shimano
We have only 1 items in stock.


Shimano SM-BB91-42A bottom bracket - pressfit for Specialized OSBB


Made in Japan 


The Shimano SM-BB91-42A is a pressfit bottom bracket that allows a Shimano Hollowtech II crank to be fitted into a Specialized MTB frame with an OSBB aluminium bottom bracket. These have a special shell width of 84.5 mm with 42 mm shell diameter. Thanks to its 24 mm bearing and axle diameter, the inner bearing convinces in terms of stability, weight and efficiency.

Shimano BB91-42A Press Fit Bottom Bracket, XTR quality, compatible with all MTB hollowtech 2 chainsets.

Complete your XTR level press-fit bottom bracket assembly for Shimano HollowTech II MTB cranks

Cups are made from fibre reinforced polymer material which reduces the risk of frame noise and damage

Set includes left and right hand cups, 2.5 mm spacer

Sealed cups keep out dirt and water

Maintenance free

Compatible with 89.5 mm (with 2.5 mm spacer) and 92 mm shells with 2 spacers (not included) 

42 mm cup diameter

Easy press-fit installation

Please note - not supplied with inner sleeve


Dcbikes Product Specifications :

Application: Cross Country

Type: OSBB

Shell Diameter: 42 mm

Shell Width: 84.5 mm

Axle Diameter: 24 mm (Hollowtech II)

Technical Information:

Bearings: steel

- for Specialized MTB OSBB Pressfit aluminium frames etc



Hollowtech II

The externally mounted bottom bracket offers better weight distribution and stability for more efficient power transmission. The diameter of the bottom bracket axle and the bearing (24 mm) was an important factor in the development, as the bottom bracket axle has a significant impact on stiffness, stability, weight and rotational efficiency.

Manufacturer Part Number:



Package Includes :

- 1 x Shimano SM-BB91-42A right bearing cup, incl. bearings

- 1 x Shimano SM-BB91-42A left bearing cup, incl. bearings

- 1 x 2.5 mm spacers


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