Although almost every brand has decided to standardize its version, the base is simple. There are 3 parameters when determining your bottom bracket:
First, Diameter (Ø)
In reality, there are not so many diameters and they are generally divided into:
- 37mm (BB90-BB95) Direct bearing to frame, Trek®️.
- 41mm (Standard press-fit BB86-BB92) for 24mm shaft.
- 42mm (Standard BB30 direct-mount) Direct bearing to the frame.
- 46mm (Standard PF30-EVO386) Standard for 30mm shaft.
- Threaded(BSA – T47) Standard threaded.
Second: width (W).
The width should be measured with the bottom bracket removed to determine the exact model by looking at the table.
Tirth: Pressfit or threaded:
If the bottom bracket shell is threaded, it will be one of the following: T47, BSA or Colnago thread fit. Any unthreaded shaft will be one of the above.
In any case, we ALWAYS recommend checking the specifications of the manufacturer of your bicycle since they often show BB´s model used.