3-Piece Bottom Bracket Bearings
This basic tutorial will demonstrate the workings of a typical 3 piece bottom bracket, showing the removal and installation of the various components that make up the bearing system.
Although there are slight size differences between different manufacturers, the basic principles of operation and assembly are virtually the same. In this tutorial, the bottom bracket shell has been cut from the frame for later use in a custom bicycle project.
The crank axle is a hardened steel rod that includes a pair of machined bearing races, tapered square ends, and either a bolt or internally threaded section at each end to affix the crank arms.
There is some debate between “axle” and “spindle” as being the correct name, but most seem to use axle now, so I will as well. Why make things more complicated, right?