Originally Posted by
Road Fan
The main wear I see is on the edge of the actual race (the actual race is the concave area), not in the middle where the balls should run. At that edge the color looks brassy. Is the base metal brass?
The "brassy" looking material is copper, which is used as a base layer under chrome plating because chrome doesn't adhere well to steel. The middle part where the balls run is the underlying steel. The balls have worn through both the chrome and the copper and are now bearing directly on the steel.