Originally Posted by
Duragrouch
Interesting, sincere thank you. If my external bearings are same, that means preload is (also) loading the sides (inboard on outer race, outboard on inner race) of the bearing grooves. I need to ponder what that means in terms of spreading the bearing load better. On hub cup and cone bearings (angular contact), preload has made a huge difference to me in durability. If the external bearings are different, perhaps not. But they do come with a torque spec on the cap, and after the first retorque, no loosening for almost 2 years and counting. Whereas with internal cartridges, they just keep getting looser and looser after that starts.
You don't need to ponder anything. Standard bearings are not designed for side loading to remove play.
And you have completely misunderstood the cap torque. They list .7 to 1.5 Nm, but then provide a tool that you use by hand and is designed to slip from your grip when it is sufficiently tight. That is supposed to work out to .7 to 1.5, but functionally it is just enough to locate the crank are against the forces of shaft and thread friction. The cap is there to remove play, not preload anything.
You are one of those people who has convinced yourself that your narrow experience and engineering textbook knowledge cause you to have a better, smarter understanding of how bikes work. But bikes don't work like jet engines. They exist in a low torque, low rpm, low temperature world where virtually all the wear and tear comes from bad specs and dirt - not treating the bearings in some super special way.
If you were having problems with bearings wearing out quickly, it was almost certainly due to something you were doing wrong, or out of spec BB shells. So I wish you would stop inventing stuff and then telling people about your new wisdom. You don't even know how the equipment you already own works.