Over at Analog, a good frame prep job is one of our favorite things to do. We get to use fancy facing and chasing tools to prepare frames for good bottom brackets, nice racks, and rad headsets. Most bikes are maculate right from the factory. Frames might have a bit too much paint, uneven paint, or imperfect planes to press headsets or brazing material in the threads of bottom bracket shells. Analog removes these foibles with sharp cutting and thread chasing tools. We carefully face and tap these surfaces to get parallel bearing surfaces.
Bearings pressed into non-parallel surfaces can bind, subtly or overtly. Headsets are particularly susceptible to binding, but bottom brackets suffer from it as well. Racks and fenders are a pain to install in unprep’d frames, so we tap all the threaded braze ons on the bike.
Not every bike needs a full frame prep, but most do. We’ll forgo it if and only if the frame comes fully pre-prepped. That new White Industries ceramic bottom bracket should to feel as good as it possibly can!