Originally Posted by
dddd
The balls are typically chromium steel and the cup races have so much more surface area than the cone races, so the cones lose their case hardening first.
2 round objects make contact at 1 point only. If they didn't they wouldn't be 'round'.
When clamed down cones don't move. All pressure from the bearings is literally concentrated at the bottom of the cone. Races on the other hand are constantly moving, with each rotation of the wheel the entire cup bearing path is touching the bearing.
Cone wear is heavily concentrated at one point. Cup wear is spread out.