Originally Posted by
dscheidt
You can say that. It won't make it true. The point of preloading an angular contact bearing is it keeps the bearing loaded at all points on the rotation. Pitting on a spindle is going to be the result of corrosion, which is going to have a lot more to do with how it was stored than how the cranks were mounted, or contamination, which will attack the whole race.
It won't make it true, but the fact that you are dead wrong about the corrosion suggests you are wrong about that too.
Some forms of corrosion are called pitting, and they even look a little bit like bearing pitting to the untrained eye, but bearing pitting is caused by metal fatigue. The geometry of the situation means the stress is at a peak value somewhat below the surface. That's where the fatigue microcracks start, and they spread upward until a pit of metal crumbles out.
I suppose the bottom of a cone always pits because that's where the contaminants sink to, but the cup doesn't pit as quickly as the cone because the contaminants are floating on oil?
A headset crown race is always preloaded axially due to weight. And it is important to preload the upper races with correct adjustment-but it's not as crucial as the hubs.