Bicycle Mechanics - Hub keeps coming loose
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10-20-09, 12:11 AM
I have a no-name front hub on my work bike that has repeatedly come loose. I have overhauled it a couple of times, and adjusted it many more, and it exists on the bike without play for a couple of days, and then it's rocking again. I have overhauled the rear one, which has stayed in adjustment.
I am sure others have had this problem, and I don't think it's because the lock nuts aren't tight enough. I've done all I can to get them on there very tight.
For those of you who have dealt with this, or may know: how do you resolve this? This may seem like a stupid question, but does it matter which way the wheel is mounted? I've eliminated the other things I can think of, though, so it's probably something stupid like that.
10-20-09, 12:18 AM
Assuming the cones are not grinding away into oblivion...chances are pretty good the hub races (cups) have come loose.
Not much can be done about it - with generics you simply replace the hub.
10-20-09, 12:39 AM
The other possibility is the treads on the axle are stripped? in that case you'd probably notice when tightening that cones and locknuts don't get thread purchase to tighten to one another, so the above diagnosis is perhaps more likely. Good to have a differential, though.
10-20-09, 01:00 AM
Thanks. I hadn't considered the cups coming loose. I assumed the cones were, as everything looks to be in ok shape.
I have considered replacing the hub. What would a decent (i.e. not bottom of the barrel, but serviceable and dependable, and certainly not top of the line) front hub cost? How much would it typically be to have a shop install it? Is this something I should be able to do myself with a spoke wrench? I have experience truing wheels, but not building them. I assume the front would be the one to start with, and it doesn't seem that hard, but I'm sure it is harder than it seems.
10-20-09, 01:09 AM
you're better off getting a new wheel, unless your rim is in fantastic shape and is very high quality. It will cost you about as much if not more to get a new hub built into your rim than it would cost to get a new front wheel. I'm in Chicago and I can custom build you a wheel if you like. PM me.
Wheelbuilding is a pretty advanced task on bicycles, but it can be learned. It does require a good truing stand, and a dishing tool and spoke gauge and a good instructor are ideal to have around.
+1 Just get a replacement wheel. Lots of low cost wheels out there.
10-20-09, 08:37 PM
If the threads are not striped keep slightly tightening the cones until the play is gone when the wheel is clamped into the dropouts. When ever you adjust a quick-release hub the bearings should should have a slight amount of play in them that goes away when the quick release is closed. The clamping force shortens the hollow axle slightly (about .1mm) and sets the preload on the bearing.
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