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Got a new trainer tire, so I removed the regular tire and tube from the rear rim and replaced them with the special trainer tire and a thinner tube. When I plied the old deflated tube for storing, I noticed that it was leaking air. On inspection I've found 3 pairs of holes which are apparently on the inside of the tube, toward the rim. I inspected the rim tape and it looks fine. In the past I've had put some extra electrical tape on the rim and then the rim tape over it. They both look fine, the electrical tape is not damaged or cut where the spoke wells are. The rims are double walled. I inspected the rims, spoke wells, rim tape, the tire - can't find the cause of the punctures. They seem to align with the spoke wells, though. What makes it weird is that all three punctures are double, there's one cut and next to it there's another, not quite parallel. It looks something like this: / \ . Check the pics also. With the tube deflated one of the puncture has the cuts 8mm apart, other has the cuts 4mm apart and the last has the cuts 2mm apart. What baffles me is that the wheel was not losing air before I took it apart. It was inflated! Only after I removed the tube I've seen these holes which are big enough that I can't inflate the tube now with a hand pump.

What can cause this? It's got to be the rim, right? Somehow the rim tape slides about and exposes the spoke wells. But why it looks fine and why did it stayed inflated until taking it off?

Wheel 26", tire 57-559, tube 40/60-559.

Thank you!

puncture 1

puncture 2

puncture 3

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    I wish that all the picture we see here could be so neat, crisp and precise! – Carel Apr 1 at 11:11
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These are pinch flats, also known as snake bites. For more info, you could have a look at What are pinch flats?, Best practice for patching snakebite pinch flats on skinny tubes and Is there anything I can do to prevent snakebites (pinch flats)?

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    Could also be damage from the tyre lever when taking the tyre off. – Carel Apr 1 at 11:09
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    I don't understand how tire lever could produce the snakebite pattern. – ojs Apr 1 at 12:24
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    Depending on the shape of the lever it is possible to fold and pinch the tube between the bead and the rim. – Carel Apr 1 at 12:59
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    Thank you all for your input! After reading your answers... as much as I hate to say it, I think there's a good chance that I may have pinched it myself with the tire lever, as @Carel suggested. This would definitely explain why the tube was holding pressure until I removed it. Now I tried reproducing the pattern by pushing the levers into the tube against a hard surface. With one of the levers the pinch looks somewhat similar, but with the other lever the pattern is almost dead on accurate. Here's a picture of it link . What do you think, could this be it? – Alex Apr 1 at 13:47
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    @Alex Yes, it can. – Vladimir F Apr 1 at 19:30

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