I was overhauling my rear hub for the first time and I noticed what seems to be a pit on the hub cup. Weird thing is it's not on the bearing race, not next to it, more like one race width away from it. The 'pit' does feel rough when I go over it with a ball point pen. I've attached a few pictures. Sorry but the lighting is extremely tricky so I also highlighted the pit and the bearing track in Paint.
The corresponding cone race is fine, as are all other bearing races (headset, BB, front hubs), as the bike has had very low mileage. The hub is a Shimano Exage Sport. What could've caused it? I really hope that was just a manufacturing defect?
Should I be concerned? Would it accelerate wear to bearings (and in turn the races themselves) if I repack with new bearings and grease. Can someone kindly shed some light? Much appreciated!
Possibly, from your description it is palpable. Practically speaking this is of no
significance and may be ignored. Just clean and check the ball bearings
before lube and reassembling the hub. Little reason not to reuse the
bearings if they pass inspection, but cheap to replace if any concern over
the bearings. Any pitting on the bearings mandates replacement.