Originally Posted by Duragrouch

From bearing company:


Radial arrows; longer equates to higher force and stress; bearing balls and cones spall sooner. Also, lack of preload causes ball skidding and scoring. Both were observed on my bicycle ball bearings and wheel cones before implementing preload; wheel hubs, bottom bracket, and pedal spindles especially, clicking was ball skidding. Not other application, but bicycle ball bearings. After replacing balls and cones, and using and maintaining preload, neither spalling nor scoring has reoccurred, now many multiples past previous maintenance intervals with all bearings feeling great. BB spindle was spalled; reversed and rotated with respect to crank to take load off spalled area, used proper preload, and was still doing great after years when I removed to upgrade to hollow-spindle design with external bearings, and have maintained preload on that.

Bearing company recommendations.

Actual experience on bicycle bearings.