One hour after my first 20-minute ride with new inner tube it exploded with "ps-BAH!" sound. Also, as you can see on the photo, two bulges appeared near the hole. The tire (25mm) allows up to 8 bar (116 psi) , I inflated it to around 7.5 (108 psi). Do you think it's simply a production defect of the tube?

EDIT: it's not a long cut on the photo, it's a seam. See full res image

enter image description here

  • With nipple you mean the valve, I presume! I'd say a production defect or an also likely pinch when mounting the tyre.
    – Carel
    Mar 3, 2015 at 19:43
  • Strange. There was some piece of something that ran diagonally across the tire, starting at that left-hand bulge and following the abrasion pattern down and to the right. But it kinda smells of an installation error -- got the tube twisted there, maybe. Mar 4, 2015 at 3:05
  • Question: How did you install the tube? Did you insert it into the tire flat, or did you inflate it a bit first? Mar 4, 2015 at 3:06
  • @DanielRHicks I installed it flat without completely removing the tire from the rim.
    – modular
    Mar 5, 2015 at 14:21
  • You should always inflate the tube slightly first -- not all the way, but to the point that it's still pretty limp. This helps prevent twisting. Mar 5, 2015 at 14:24

2 Answers 2


What that looks like to me is that you had the tube pinched (folded) up along side the value stem. That would explain both the cut and the bulges. That cut looks like a tear - a faulty tube would have more of a clean split.

When you mount tire make sure the valve is free (you can push it in).

  • Sorry for not so clear photo. It's just a seam, not a cut. Also I guess if the tube was folded I'd feel it
    – modular
    Mar 3, 2015 at 20:21
  • You guess you would feel a fold? Just how would you feel a fold? Did you test valve free or not? I see the detail and that is a pinch cut.
    – paparazzo
    Mar 3, 2015 at 20:26
  • Judging by place of the hole it seems plausible that I indeed left the valve too deep in the tube. Though it's doubtful since after inflation I screwed the nut on the valve stem all the way.
    – modular
    Mar 3, 2015 at 21:14
  • I think the fold would feel like a bump on tire though it's just a hypothesis
    – modular
    Mar 3, 2015 at 21:15
  • If you are sure it is defect then why did you post the question? Just because you screwed on all the way does not mean it was all the way out. I take it you did not test for valve free. I am not here to argue with you. That is what I see - take it or leave it.
    – paparazzo
    Mar 3, 2015 at 21:17

In addition to what Blam suspects, verify you don't have any debris in your rim, and that your rim tape is not damaged. If this tube was a replacement after a flat, it's possible whatever caused the previous flat remains to torment you further.

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