In this article, we use so-called affiliate links. With every purchase through these links, we receive a commission from the merchant. All relevant referral links are marked with . Learn more.
Design: Different press-fit bottom brackets for MTBs
The bearings are either pressed directly into the bottom bracket shell (e.g. BB30) or in a plastic shell. (1) inserted horizontally into the housing (e.g. Pressfit BB92). The latter variant is widely used in mountain bikes today, as the tolerances in frame construction can be somewhat more generous here. For the bearings (2) These are usually industrial bearings that can be replaced at low cost. With Sram, the bearings are additionally sealed using sealing discs. (3) protected from soiling.
Pressfit standards at a glance
The most common bottom bracket standards are Pressfit BB92 / Pressfit GXP: 24 mm axle, 92 / 89.5 mm housing width, 41 mm housing diameter Pressfit30 (PF30): 30 mm axle, 83 / 73 / 68 mm housing width, 46 mm housing diameter BB30: 30 mm axles, 85 / 83 / 73 /68 mm housing width, 42 mm housing diameter
Three special solutions for press-fit bearings
Time and again, bicycle manufacturers are causing a stir on the market with their own standards. For the BB95 standard, the bottom bracket shell was blown up to a width of 95 millimetres. The bearing seats were laminated into the frame and the bearings pressed directly into them. For current models, Trek is once again using the PF92 standard. There are also special bottom bracket solutions for fat bikes. Truvativ's BB121 bearing, for example, has an installation width of 121 millimetres.
How to find the right bottom bracket for my bike
To find the right bottom bracket for your frame, you need the following measurements: the width and diameter of the bottom bracket shell and the diameter of the crank axle (24 or 30 millimetres).
This is how it's done:
Mounting types: This can be used to remove press-fit bottom brackets
You need special tools to remove press-fit bottom brackets: an extractor and the press-fit tool. Both are now available at reasonable prices. We do not recommend DIY solutions from the hardware store.
You can read this article or the entire BIKE 11/2017 issue in the BIKE app (iTunes and Google Play) or download the issue from our online shop reorder:
Read in the Apple App Store
Read in the Google Play Store
Order in the DK-Shop
Stefan Frey
Editor
