Well, it has happened again. I messed up a hub, and it can’t be fixed.
It’s one of those lessons learned when switching components. For decades I used Campagnolo. You learn the ins and outs of parts and everything is wonderful.
New parts have new problems and quirks you need to learn. Take the Shimano Ultegra 6700 front hub. I had a squeak that I couldn’t identify, which turned out to be a loose front quick-release. So I cranked it down, hard.
I also repacked the loose-bearing hub (11 3/16″ balls by the way according to Shimano) and when I did so, I may have adjusted it a bit too tight. It’s one of those adjustments that requires finesse and an awareness of what’s right for a particular hub. You want a small amount of play. That’s because when you clamp the quick release, there’s more compression of the threaded bearing race on the clamp side.
All it takes is a bit too much pressure for the bearings to bind. That binding caused the dimples in the hub race. Back in the days of Campagnolo, races were replaceable, but not Shimano’s. I don’t think this hub is toast. It’s probably going to last quite a while, but not as long as it might last with proper treatment.
Service sealed headsets and bottom brackets
While you’re servicing your hubs, note that just because you have a sealed-bearing headset doesn’t mean it needs no maintenance. The bearing cartridges ride on races and they need grease. If not greased, they’ll start making noise or, worse, wear out the headset prematurely. I didn’t service mine for two years and that was probably a year too long.
I took off the bottom bracket on the Shimano 6700 and while it doesn’t look like it needs any maintenance, it’s always a good idea to grease the threads and clean the parts. Sealed-bearings are designed to emit a bit of grease. They’ll dry out, eventually, and need replacing.
Addendum: As I look at the photo, it occurs to me that the dimples are low on the race. I’m wondering how it could dimple so low? Are the bearings really riding there? Odd.
Addendum 2: I was using 7/32″ bearings (Campy on my mind) rather than 6/32,” and that could explain why the bearings rode low in the hub. I’ll replace them with the correct count and size and see what happens.
Addendum 3 (7/12/2015): Yes, the hub has issues as a result of the dimpling. There is a distinct sound of bearing rattle. Although it’s intermittent, increasing as the hub warms up, it’s high on the annoyance chart, so I’ll replace it.