My rear tire was keep going flat while riding, so I felt around the tire for any punctures or abnormal ‘signs’ that may be causing the problem. One area felt too thick, and at first, I thought I just overinflated it and somehow the air got trapped. Later, I ended up pushing my bike into the rocks, and when the tire tread came off, I saw that the inner tube had literally folded up into a ‘Z’ shape inside the tire. How did this happen? I have never seen anything like this before.

  • Either you had the wrong tube or you were running the tire (almost) flat. Commented Oct 3, 2019 at 23:12

2 Answers 2


Most likely incorrect tube and tire combo. Check your tube range if it matches the size of your tire. Could also be that you seated the tire incorrectly.

  • Like a 29'' tube in a 27.5'' or 26'' tyre.
    – Carel
    Commented Oct 1, 2019 at 13:01

This can happen if your tire is underinflated and you use your rear brake a lot. When you brake, the tire drags and moves a little bit around the rim. Since the tube is anchored at the valve stem, it stretches on one side and bunches up on the other.

  • That makes sense. My tire was under inflated, and I usually use my rear brake more than my front one. Thanks.
    – Steve
    Commented Oct 1, 2019 at 18:04

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