Originally Posted by
on the path
I may be overstating the obvious, but I was only talking about loss of rigidity, and mainly in regards to the sole of the shoe. I was not talking about breakage. Breakage, of course, is visible and obvious. Gradual reduction in above mentioned rigidity, if that's truly what takes place, would happen in such minute increments that the rider would never be able to notice or gauge the changes.
Also, any suggestion of "cold working", or work hardening, of material can not apply categorically. Any type of hard plastic, nylon, carbon fiber, etc., used for rigid shoe soles, is not malleable at ambient temperatures in the way steel or other non-brittle metals can be.
Isn't that how fatigue happens? Even to plastic? Just like steel, nylon is semi-crystalline. The crystals provide strength and stiffness. The amorphous regions provide ductility. Flexing the material (working it) causes crystallization at the flex point which results in brittleness due to the loss of amorphous material. Hence fatigue failure.