General Cycling Discussion - Back wheel inner-tube keeps popping...
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11-06-11, 04:18 AM
so here the deal, this is happening to me on two seperate bikes, same make, same size, same uses. My back inner tube keeps bursting entirely too often and I can think of no reason why they should. any suggestions as to why this is?
11-06-11, 04:41 AM
Are your tyres properly inflated? Soft tyres increase the risk of 'pinch flats' where the tube is pinched by a bump and torn. Since the rear wheel carries more weight than the front, this would explain why you're only getting punctures at the rear. Bike tyres generally need much higher pressures than car tyres.
11-06-11, 08:47 AM
Several other reasons---Tyre located incorrectly and poor quality rim tape come to mind first of all. Then is there someting in the tyre still such as a thorn or bit of grit/glass. May not be easy to find so turn the tyre inside out and use a cloth to try and find it. If nothing found then use your hand to feel for it--When blood appears you will have found it. Hence using the cloth first.
11-06-11, 09:40 AM
Since you typed 'bursting' I assume you are not talking about a puncture.
One thing to watch out for is installing the tire on the rim properly. Usually there is a witness line that should be just above the rim. Chick and make sure it is evenly spaced all the way around. The most likely rise is around the valve stem.
If that is not evenly spaced, the tube can work its way out in the high spots. Sometimes I used to notice the ride getting uneven just before something like that. I'd check the tire and there was a bit of a bulge where that high spot was rising.
A couple of times I was able to let a little air out and just try to brute force that rise back down a bit. At least that got me home without the pop.
11-06-11, 10:04 AM
What you're describing is a blowout, and since the tire being ripped to shreds isn't part of the description, then what you likely have is a pinched tube due to improper installation. ClosedOffice had it almost right; except the tube doesn't 'work its way out,' the uneven bead is caused by the tube already being between the tire and rim. For some reason, tubes trapped that way never work their way back into the tire, sooner or later they always escape. And when they escape, POW! So, here's what to do to avoid it in the future:
First, mount the tube and tire. Then inflate the tire to 5 psi or so. Now, working your way around both sides of the rim, push the tire's bead away from the rim. if the tube is 'pinched' there between bead and rim, the small amount of pressure in the tube will cause the tube to return to its intended toroidal shape inside the tire's carcass. When you're done working your way around both sides, spin the wheel and observe that the 'witness line' is even along all points of the rim. Then it's safe to pump up to full pressure.
This past summer, a friend got a new bike and was plagued by blowouts. The shop kept replacing both tubes and tires under warranty, to no avail. After about a dozen interrupted rides, I finally grabbed the wheel from him and performed the procedure above. He hasn't have another flat since. The moral is, even shops can screw up mounting tires.
Is your tube large enough for the tire?
11-06-11, 06:57 PM
Tube must be damaged, where is the damage evident? Inside? Could be the rim strip is not covering the spoke holes.
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