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I posted a question some time ago about vibrations in the frame of my road bike (a 1973 Sekine). Recently, I determined that the rear wheel is sliding back and forth across the axle, with about 0.5cm of play in it. It takes a little bit of pressure to move it, which is why I didn't notice it before (the wheel spins just fine when held off the ground), and I suspect that it is getting worse over time.

My question is: What does this mean? I assume it's not good, but I'm not clear on what has happened exactly. Is this due to wear on the freewheel? Is it just something I need to tighten?

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3 Answers 3

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It means the bearings are loose. (The main bearings, not the freewheel bearings.) It could be they're worn, but it's also likely that at some point in maintaining the bike you accidentally unscrewed one of the cups.

I'd suggest you take it to a bike shop. They should be able to fix it in about 3 minutes (though there's some danger that the bearings are messed up, if you've ridden it long in this condition).

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Some danger = almost certainly not repairable, if there is that much play, and given the time frame you've had the issue while riding the bike. –  zenbike Nov 8 '11 at 4:33
    
@zenbike, do you mean not repairable at all, or not repairable in 3 minutes? –  Colin Newell Nov 8 '11 at 8:50
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Most likely not repairable at all. The damage that typically results from riding a hub that loose is usually to the bearing races, which are an integral part of the hub. Repairing it means replacing the hub in most cases, and with the cost of labor and parts, it is usually more cost effective to replace the wheel. –  zenbike Nov 8 '11 at 9:44
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I've seen worse be made rideable. Probably no longer fit to compete in the Tour de France, but I don't think that John is expecting that. And, in any event, it's not that expensive/difficult to get the bearing tightened and see how bad it is. –  Daniel R Hicks Nov 8 '11 at 10:59
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@DanielRHicks: Didn't mean to say it wasn't worth trying to repair, just not to expect too much. I always work from the perspective of wanting my equipment, whether computers or bikes, to be in as perfect a condition as possible. If there really is a half a centimeter of play in the hub, and it really has been ridden for at least the 6 weeks implied in the question, then there will be significant damage to the bearing races, and they will not be repairable without replacing the hub. You can choose to ignore damage, tighten it up, and ride anyway. Doesn't make it a good idea or safe to ride. –  zenbike Nov 9 '11 at 4:35
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It is also possible that the axle is broken, especially with a lot of riding on rough roads. (I replaced a broken axle on someone'sbike not too many years after 1973 and earned a nice bottle of Petrus.)

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Yep, would be fairly unlikely on a new bike of any quality, but an old bike with a bit of corrosion could see that happen. –  Daniel R Hicks Nov 9 '11 at 1:00
    
If he's had the wheel off, however, that would be fairly immediately obvious, and the play would be more in the 1-2cm range if it was still on the bike. –  zenbike Nov 9 '11 at 4:38
    
It's possible it could have broken as he was reinstalling the wheel. In any event, this would be easy to diagnose -- remove the wheel and see if the pieces of the axle fall out. –  Daniel R Hicks Nov 9 '11 at 12:30
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If you say sliding back and forth, and 0.5 cm of play that only manifest with a moderate pressure against, I would recommend, besides the very good answer given by Daniel Hicks, that you check if your axle is not sliding in the dropouts.

(Usually, lateral play on the bearings manifest itself even with the slightest pressure, and is much smaller than half a centimeter - or you meant half MILIMETER?)

Obviously, this suggestion only applies if you have horizontal dropouts.

And as they said, the freewheel does not seem to be the culprit.

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Good point -- it may be that the axle nuts simply need tightening. –  Daniel R Hicks Nov 8 '11 at 15:59
    
Thanks for the suggestion. The dropouts are not horizontal. The play really is 0.5cm though, but I suspect it started out much smaller than that. It's quite difficult to ride at this point... –  John Doucette Nov 8 '11 at 19:21
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@JohnDoucette: You should not be trying to ride it at this point. You are only causing more damage to the bike by doing so, and should it fail completely, you risk damage to your person, as well. –  zenbike Nov 9 '11 at 4:37
    
@zenbike I only figured this out a few days ago and have not ridden it since (despite the highly unreliable bus system!). Prior to the day I figured it out, it seemed a little off, but still quite ride-able. Won't be riding it again until I get this fixed. Thanks for the concern though. –  John Doucette Nov 9 '11 at 5:05
    
@JohnDoucette: We do the best we can. It's unfortunate that you didn't find it sooner, but it is what it is. Cross your fingers that it's not too painful to your wallet to repair it... –  zenbike Nov 10 '11 at 10:56
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