Hub cup race defect

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  • Has anyone ever seen something like this on a cup race, the two marks seem to be part of the race surface, running a biro over them they stand slightly proud. Is this just a manufacturing defect or could it happen from contaminant build up during use ? It's a 105 hub that I bought second hand and have just stripped it.


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  • Doesn’t look like a manufacturing defect, you’d assume it’d be spotted during QC before polishing the race at the factory.

    Most likely a couple of chunks of foreign metal got inside and became pressed into the race by the balls.

    What condition were the balls in when they spilled out? Any missing chunks out of them?

  • Yep just checked and some of the balls are pretty badly pitted -see pic below for worst offender, looks like its worn right through the outer layer. Suprised that the debris could fuse itself to the race though! The lumps look like they are slightly below the track on the race. Might try removing them very carefully with a dremel. Suprisingly the cones are in perfect condition, these normally go before the cups.

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  • Turns out the cone on that side is toast as well, just hasn't seen the damage on first inspection. New cones are available for about £10 or I could get an entire new hub for £25. However that means rebuilding the entire wheel, which is something I've been keen to learn for some time, but have no experience of so there's a good chance it will go wrong!

    Am I better off just replacing the cone and accepting the cup may eventually cause an issue or trying to replace the hub ? The rims and spokes seem in good condition and I don't want to pay out for replacing those as well at this stage. Has anyone got experience of swapping out a hub ?

  • Replace the hub. I would jot use cups in that state.

  • it probably will go wrong, in so far as you will lace a spoke the wrong way and have to redo it or get annoyed with truing it.

    but that's just part of the process

    there are lots of how to videos out there.

    it isn't difficult, just set aside a couple hours.

    at the very least, you will have learnt a new skill and get a new wheel out of it

  • That was my thinking. It wasn't a particularly expensive set - bought them second hand , and I only need the rear at present so may see it as a chance to learn on something not too valuable. I'd really like to learn. It does however involve the cost of a truing stand, spoke key, tension meter etc! Any suggestions for a budget stand (cheaper than a Park one) or are they a waste of money ? Am I better off with a fork and ziptie ?

  • I've done several wheels with the fork + ziptie method, but it definitely adds to the complexity. Buy a stand if you plan to use it more than once, it will save you a lot of hours faffing.

  • Spoke key is a few quid, you don’t need a tension meter. I’ve bought two truing stands, never paid more than £10. (2ndhand)

    Unless you’re doing it pro you don’t need expensive gear.

    I’ve trued loads of wheels in the frame using brake pads as guides. Can do it that way if you don’t want to spend out but a stand would help

    Should you be in Brighton you can borrow my stand if it helps

  • Cheers for the advice, I'll pick up a spoke key and give it a try in the fork. Can always take it to the lbs if it goes wrong !

    Thanks for the kind offer of the stand, but I'm in Bristol (did live in Brighton many years ago!)

  • Are we talking about those two dots? Yeah lools like a bit of ball or cone has welded itself on there, not in the race though?
    So long as its not in the raceway id....
    But another 105 hub the same type and swap over axle/cones/balls, you get a shiny new qr too. Cones that fit modern shimano hubs are not that easy to get and usually 2 of them is not far off a whole hub.
    If it sorts the problem great, if it doesn't then you now have a new hub shell too, so you can buuld that into your existing wheel ;)

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Hub cup race defect

Posted by Avatar for zootsuit @zootsuit