The wheel, the lever, and the inclined plane...and press fit

The wheel, the lever, and the inclined plane represent fundamental principles that underlie many more complex tools and machines. They're building blocks of more advanced technology that took us out of the stone age.

Threads use the principle of the inclined plane, to create a secure joint that can be incrementally tightened to a desired firmness (torque) at a desired rate (thread pitch)

Then came press fit. It's the equivalent of pounding it in with a rock. Sure, you are better off to squeeze it in with a controlled press -- utilizing threads on the tool -- but you're basically just shoving it in there and hoping it stays securely and functions quietly.

Yesterday was press fit day in the workshop. One bike was a carbon Salsa full suspension mountain bike that the owner cleans with a hose, "but only carefully." It had noises in the bottom bracket and headset. Videos I watched to learn more about the inner mysteries stated that press fit BBs are simple and easy to work on, but noted that you should only remove one when you are planning to install a new one. What the assembler hath pounded in there, thou shalt not pound out. And pound them out you do.

One tool, from Enduro, used gentle methods of persuasion, but all of the others called for an assistant and a hammer.

The second patient was an Orbea road bike that we've been trying to get dialed in for about a month. The parts on it were transferred from an older Orbea that had cracked. It has a mystery noise that sounded like creaky bottom bracket, but may prove to be a drive train noise amplified by the large, resonant carbon fiber frame. Fiddling with that is time consuming, and time is money. If you're getting compensated for the time, it's a win. It's unclear at this time how fully we will be compensated. When a job drags on with mysterious afflictions the billable hours get blurry.