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I noticed recently that my rear tyre was rubbing on the frame when I was pedalling hard; the wheel had a bit of horizontal play in it, so I thought the cones might need tightening. Anyway, I left it another couple of days, until at some point the wheel suddenly developed a lot more play in it than before. I looked down and saw this:

TL;DR: My rear hub currently looks like this. You can see the bearings inside; none have come out yet and I've stopped riding the bike. Will a hub service sort this out? Or is it likely that I will need a new hub/wheel?

Rear hub with bearings showing

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    The hub needs to be disassembled, cleaned, and reassembled, taking care to get the "cones" holding the balls in to the proper tightness (a little bit of an art, or a lot of trial-and-error), and taking care to get the thin lock nuts just outside the cones tight against the cones. The only "special" tool needed is a thin "cone wrench" of the proper size -- otherwise you just need a few open-end wrenches, solvent to clean things up, and fresh grease. (Though it doesn't hurt to replace the balls while you're at it -- they're cheap.) Commented Jul 25, 2014 at 15:00

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That looks fixable to me.

What probably happened is the locknut was loose, and continued riding caused both cone and locknut to unscrew. It's a good job you've stopped riding that bike - riding on that hub now would cause significant damage.

When a hub has a bit of play, the balls are free to move across parts of the cup and cone that aren't designed to support load. Those areas may not have been heat treated and/or polished. That can cause metal wear, resulting in particles grinding between the balls and the 'proper' bearing surfaces. Result: pitted cups and cones.

When a hub has a lot of play (as in your case now), the problem is exacerbated further - the balls may slip out of place completely and bind the hub, causing irreparable damage.

That hub is dirty and the grease is foul. Pull the axle, clean the hub inside and out, and clean the axle, cones, and locknuts. Use a good de-greaser, or failing that, ethyl alcohol, lighter fluid, or equivalent. Wipe it all clean with a lint-free cloth and inspect. If the cups have any scratches you can feel with your little fingernail, I'd ditch the wheel. If the cones have any pitting, I'd get a new pair. Whatever the state of the innards, get a new set of bearing balls.

Sheldon will show you how to re-pack and adjust the hub. It's not difficult, just a bit greasy and fiddly. Wear latex gloves if you like.

It doesn't look like a particularly special hub, so I wouldn't pay a professional to do it; balls and grease are cheap. Do your best and ride it 'til it fails; then just get a new wheel (it's rarely, if ever, worth the cost of lacing a new hub to an old rim).

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    Replacement axles for cup-and-cone bearings are normally quite cheap, but if the hub surfaces are rough it'd probably most economical to replace the wheel.
    – Emyr
    Commented Jul 25, 2014 at 11:47
  • If that's a ball you can spot there at the top the hub is most likely dead.
    – Carel
    Commented Jul 25, 2014 at 12:06
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    Dead is relative. If the bike's a beater, you can still get a lot of life out of a hub that some people would call trash... Commented Jul 25, 2014 at 13:21
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    @Carel - When I was rehabbing bikes for Christmas Anonymous I saw hubs much worse than that turn out OK. Commented Jul 25, 2014 at 15:02
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If all else fails you could just replace the hub/axel. Provided you can find one where all the dimensions are the same (flange spacing, flange diameter, number of holes, axel length matches drop-out spacing, etc), then you can re-use the same spokes/rim. Just unlace, then relace. Or if you simply want to get back to the pedaling and don't want to deal with spokes, just buy a new wheel.

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