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enter image description hereI'm trying to patch a hole in my bike tube. So as usual I pumped it up enough so that when I placed it in the bathtub full of water I could see where the hole is. But something odd happened and I can't get air to distribute evenly into tube. It's super inflated pregnant looking on one side and super skinny on the other. What caused this? Is it usable? How to fix it?

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  • 1
    Are you describing the state of a tube alone or a tube in a tyre? Do you have a photo? It would help a lot. However, a tube alone is not supposed to hold a significant pressure and can bulge at some place. Dec 29, 2022 at 19:44
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    After seeing you inflated the tube outside of tire and the valve area, it's very normal. İn fact, if you pump more, it will explode. There is nothing wrong with it. Dec 31, 2022 at 11:06
  • 2
    The air is distributing evenly. That is why the weaker parts of the tube are expanding more ;-). Jan 1, 2023 at 14:56
  • You should probably get that checked out by a doctor.
    – MaplePanda
    Jan 1, 2023 at 19:57

4 Answers 4

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Tubes aren't designed to be stretched; they are simply there to hold the air while the rim and tire contain the pressure.

Consider what happens when you blow up a long thin balloon.

  • First, the loose balloon inflates until it is uniformly full but with little pressure.
  • Then, one part of the balloon (typically either one end or the other) will start to bulge.
  • Then that bulge will get larger.
  • Then the bulge will spread along the length of the balloon.
  • Once the entire balloon is uniformly filled, it starts to uniformly inflate.
  • Then it pops.

Exactly the same thing is happening with the tube.

  • You inflate it until all looseness goes away.
  • Then the pressure causes the weakest part of it to start to bulge.
  • etc.

But tubes aren't balloons, and they really aren't meant to be inflated to the point of bulging.

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If you are just inflating a tube alone, it will be uneven above a certain pressure. It is not supposed to hold significant pressure on its own. It is used inside a tyre. If you did not overstretch it, it is usable.

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    Concur - a bare tube starts expanding at about 3 PSI. Its the tyre+rim that constrain the tube and hold the pressure, the tube simply stops the air from leaking out.
    – Criggie
    Dec 29, 2022 at 20:36
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The manufacturing process isn't perfect and the wall thickness of your tube varies. The thinner part is weaker so stretches (bulges) more. It's very common, the tube is still useable and, no, it cannot be "fixed".

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Any patches on tube? Because the only thing I know that causes inner tube to inflate like that is patches.

...or, heavy scuffing on a part of an inner tube, for some weird reason.

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  • 3
    The reinforcement around the valve stem also causes a restriction. I think I am seeing a valve stem (with a blue cap) on the extreme right of the photo behind the size information, although the position implies the tube has reversed its curvature due to the excessive pressure. Dec 31, 2022 at 9:56
  • Yes I have 2 patches on tube
    – Alison
    Jan 1, 2023 at 0:04

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