A customer brought in a WH-RS21 for service.


There was a slight centering issue on the rear wheel,
and otherwise I just did some fine wheel truing.


The spokes on the front wheel were bent in all directions along their flat side,
so I straightened them out and tightened them up a bit.
The front hub had an abnormally rough, grinding sensation when spinning,
so I disassembled it to take a look inside. The cone race had pitting damage,
but that wasn't all — scattered throughout the hub interior were
fine metal particles that appeared to be shavings from the ball bearings.


↑Of the bearing balls, 11 on each side for a total of 22


one of them had its surface peeling off.
The silvery flake-like particles scattered throughout the hub interior
were metal fragments that had come off from this ball.


↑The opposite side.
This side didn't show any particular wear.
The bike apparently has about 3,000 km of riding on it, but since I need to source a replacement cone race,
I reassembled it as a temporary fix. However, I didn't want to use this bearing ball anymore,
so I discarded it and replaced it with a new steel ball of the same size.