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Old 02-10-09, 06:06 PM   #1
DMora13
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Suddenly wobbly rear wheel

I'm guessing it was the pothole I hit on my commute home. After that I noticed a very slight wobble in the rear wheel that would become more pronounced the faster I went.

Does it sound like my wheel needs to be trued? I replaced my rear wheel back in November. I checked the spokes and they are all fine.

And should I stay completely off of it? Ride it to the shop? Would it handle another day or two of commuting? (12 miles roundtrip) My bike is a Gary Fisher mountain bike.

Thanks!
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Old 02-10-09, 06:13 PM   #2
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Really hard to say, without seeing it. But I am leery of advising you to ride it again.

A wobble on the rear that is bad enough for you to feel is pretty bad.

It may well be possible to bring it back into true without making the spoke tensions too uneven. Getting a wheel to spin true is not a problem: getting it to spin true with reasonably even spoke tention might be harder here. Depends on how bent it is now.

On the other hand, a rear wheel failing catastrophically is not nearly as exciting as a front.

Do you have a spoke wrench that you can use to straighten it out a bit to get you through the next trip?

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Old 02-10-09, 06:26 PM   #3
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No spoke wrench

When I say "checked the spokes" I mean I only checked to make sure none of them were wobbly. I don't know how to true or adjust the spokes.
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Old 02-10-09, 06:47 PM   #4
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Take a good, long look at the spokes - make sure they are all there. You might have busted 1 or 2. That would throw the wheel off, causing the wobble. Next - spin the wheel slowly and watch the brake-pads. If the wheel is out of true, the brake-pads will tell you as the wheel will be coming closer to a pad as it revolves. Make certain the wheel is bolted into the stays properly. Now try pushing on the wheel side-to-side. Any play? If yes, the hub may be damaged or have simply loosened up. If damaged, you may have a bent axle from impacting the pothole.

In any event, if it's just out of true (watching distance from brake-pads), this is a relatively easy fix unless the rim itself is bent. That may require a new rim and having the wheel built, or buying a ready-made wheel. If you have broken a spoke or two, your LBS should be able to install new spokes. If it's the hub - you might just need the hub adjusted, or it could be bad and, again, a new wheel would be needed.

Good luck.
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Old 02-10-09, 07:09 PM   #5
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Check for a broken axle
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Old 02-10-09, 08:28 PM   #6
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How about a wheel that moved in the dropouts (assuming non-vertical)?
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Old 02-10-09, 10:39 PM   #7
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I am sure you broke a spoke. You can sort of true it by loosening the 2 adjacent spokes and tightening the next 2. This will make it good enough to ride to the bike shop. See the Sheldon Brown website for spoke adjustment
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Old 02-11-09, 06:55 AM   #8
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Generally, an out-of-true wheel is very very difficult to feel while riding, unless the tension on the spokes has let go. If the spokes feel "tight" (basically just not "loose") then this is likely not the problem.

Usually when a wheel has a visible wobble and you can feel the bike shimmy it is because the tire is cut part way through and has developed a bulge.

I suggest you check the trueness of the wheel - pick up the bike and spin the wheel and look at the gap between the rim and one brake pad... if the size of the gap changes considerably then your wheel is out of true. At the same time, check the tire for any bulges as it rotates.

A bulge in a tire is an indicator that it is about to fail, which is potentially more catastrophic than an out of true wheel. If you hit a pothole hard enough it is possible that you cut the tire. If you dent the rim it can cause the tire to come in contact with the brake pad, and that will also cut the tire very quickly.
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Old 02-11-09, 09:15 AM   #9
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Good stuff!

Thanks everyone- all of your advice is tremendously helpful.

I've checked the spokes several times and I don't think any of them are broken or missing. With my previous rear wheel, I experienced a few broken spokes and have a little bit of experience with that.

When I spin my wheel, the distance between the rim and the brake pads stays the same, so I'm guessing the wheel does not need truing.

And because my bike is a quick-release, I also tried releasing and tightening up the rear wheel, but that made no difference.

What is sounding more like the possibility is maybe a bulge in the tire, because of the way it wobbles on the outside of the tire. I am going to try replacing the tube today and hopefully that will fix my problem.
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Old 02-11-09, 09:47 AM   #10
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Quote:
Originally Posted by DMora13 View Post
What is sounding more like the possibility is maybe a bulge in the tire, because of the way it wobbles on the outside of the tire. I am going to try replacing the tube today and hopefully that will fix my problem.
The tube is soft and squishy, it will fill and assume the shape of whatever casing you put it in. Replacing the tube won't do squat if you have a tire that's damaged or about to split open. Look your wheel over real close see if you can spot it bulging somewhere. Then pull it off for further evaluation. Some people carry cut-off sections of old tires with them to use as liners if they spot a sidewall trying to split on them during a ride. Dollar bills folded over and placed over the crack on the inside of the tire have helped many riders finish their ride.
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Old 02-11-09, 10:41 AM   #11
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Originally Posted by dabac View Post
The tube is soft and squishy, it will fill and assume the shape of whatever casing you put it in. Replacing the tube won't do squat if you have a tire that's damaged or about to split open. Look your wheel over real close see if you can spot it bulging somewhere. Then pull it off for further evaluation. Some people carry cut-off sections of old tires with them to use as liners if they spot a sidewall trying to split on them during a ride. Dollar bills folded over and placed over the crack on the inside of the tire have helped many riders finish their ride.
Agreed. You can likely reuse the old tube, but the tire almost definitely needs replacing if it is bulging (I don't know anything about installing a "boot" to repair the bulge or cut. but I assume it is for temporary emergency repairs only).

You will also need to determine what caused it to bulge. The most frequent cause of a tire bulge is being torn by a misaligned brake pad, or by a brake pad that hits the tire in one spot because of a dent in the rim. Other possible causes are riding with the tire pressure too low so that the edge of the rim pinches the sidewall against the ground (or against the edge of a pothole), or an improperly installed tube that is pushing the tire over the sidewall of the rim. Any way you look at it, riding with a cut or bulging tire is bad news and needs to be corrected soon, as it will eventually cause a blow out.
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