Bicycle Mechanics - Really Uneven Back Tire
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I just recently got my first ever rebuild completed, and took it for a spin. Early 80's Schwinn. Things are good, except that the rear tire has a major variance in it. I stuck it on a stand, and it has almost a 1/4" dip in it. (thud, thud, thud....lol) I used the original wheels, which don't seem to have any apparent dips (def. not THAT big).
So....what are my options? I had brought the wheels in to be 'trued' a few weeks ago (they basically said they'll never be perfect, but tightened them up for me). Think I need a new rear wheel?
The beast, near completion (gonna flop and chop the bars, run some shift cable, maybe a back brake, fenders, lights and reflectors, new pedals eventually)
05-19-06, 08:08 PM
First of all, check if it's a problem with the tire or the wheel. Unless the answer is evident by looking closely at the tire, dismount the tire, reinstall the wheel, spin it and check with a small screwdriver to see if the wheel is fairly straight or if it dips that way. If it's the wheel, then it needs to be fixed.
If it's the tire, I see 3 possibilities:
- improperly mounted tire: check if the tire bead is properly seated on both sides and all around;
- flattened tire: because it was in the basement at 5 psi for 20 years;
- defective or past-due tire.
I had a 6 year old tire that recently developped a major thump. No idea about the source of the problem, except I leaped hope going up and down with about 30 psi in the front tire. Turned out that not only the rubber was brittle, but the casing was tearing apart in a couple of places.
You probably have non-hooked rims and your tire is not seating evenly around the rim. If so, be careful how much pressure you put in the tires. Newer, high pressure tires need hook rims to hold the bead in place.
Guess I should have specified - I bought new tubes and tires. Only the wheels are original.
I'll check it all more tomorrow. I tried deflating it and trying to reseat the tire in the rim, but it's still thumping. But, it's late, and I need to go to bed, even though it's driving me nuts. :)
05-20-06, 10:05 PM
I think your bike looks great in the pics. I have owned a Schwinn LeTour since 1973. It sat around for five or so years after my kids went off to college. When I got back into riding I was surprised to discover how much things had changed and how little I knew about bikes. I bought new tires and then proceeded to blow out one tube after another from over inflation.
Finally changed to newer wheels with hooked rims and Armadillo tires and that fixed the problem.
I was reluctant to move away from the OEM wheels, but once I did, I solved a lot of problems.
I am surprised the LBS told you they could not completely straighten your wheels - I've never heard that from anyone - but, maybe in your case, it's true.
Whatever you find as the cause, post back so we can learn all about it.
There may be a kink in the inner tube
05-20-06, 11:20 PM
Hmm, how could it be the tube? At 5psi, the tube by itself will expand bigger than the tyre itself. When it's inside the tyre-casing, it will have expanded fully to the inner space of the tyre. Then all additional pressure will be pushing on the tyre-casing itself.
My guess is the tyre-seating too.
- When installing, add a pump or two of air into the tube so that it's round.
- Then insert tube into tyre, stick valve-stem into hole on rim and push the entire ensemble onto teh rim by hand, no tyre levers needed.
- Push up on the valve-stem to ensure that the tube's not caught beneath the tyre.
- Push the sidewall sideways and look into gap between tyre and rim, shouldn't be any tube showing.
- Work your way around the tyre inspecting every single inch of it. No tube should be squeezing out between tyre and rim.
- Pump up to just 5-10psi and manually adjust the tyre so that it rides evenly on the rim. There shouldn't be any lumps or dips anywhere.
- Gradually pump up tire, spinning to ensure it's even seated on the rim.
the tire visibly dips down at the valve on the rear. schwinn rims are notorious for seating problems. danno's advice is very good, i might a little soapy water on the tire bead can work wonders in seating a stubborn tire.
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