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I have a hybrid bike and I am having a very strange problem with deflating tires. My bike has 700C 35/43 tubes

I have changed 3 tubes in the last 2 weeks because something very strange is happening.

Tube 0

  • That I had for a long time punctured
  • I found the small hole

Tube 1

  • I change the tube and pump it to the suggested pressure of 80-85psi.
  • I ride it for 1 day, check the pressure, it stays at 80-85
  • I leave it overnight, check the pressure, ride it for 1 more day, check the pressure, everything is fine
  • I leave it overnight, the tire is completely flat. I

Tube 2

  • I change the tube and pump it to the suggested pressure of 80-85psi.
  • I ride it for 1 day, check the pressure, it stays at 80-85
  • I leave it overnight, check the pressure all is fine, ride it to the supermarket, pressure is fine. Go in for 1-2 hours, come out, tire is flat.
  • I pump up the tire, ride home, check the pressure, everything is fine.
  • I leave it overnight, check the pressure in the morning, everything is fine.
  • ride to the office, check the pressure, everything is fine.
  • come out for lunch 3 hours later: tire is flat.

Repeat with one more change of tube. Same result. Completely random deflation. I visually and tactilely inspected the rim, the tire, the tape and cannot find any problem. The tire is not new, sure, but it is not bald either. Should I replace the tire? The whole rim/wheel (more expensive, also, the cassette is difficult to remove and I have never done it)? The whole wheel with cassette? The whole bike?

I am somewhat technically minded so I tried to understand but my observations essentially are useless as I can find no logical pattern. Has anyone had any similar experience?

Thanks!

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    Did you find any holes in tube 1 and 2? Did you inspect the rim and tire where the holes occured?
    – Michael
    Mar 8 at 21:32
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    you might have something (or several things) slowly working their way through the tire. You might need to take a cotton ball and wipe in the inside the tire. Even the small protrusion will catch the cotton.
    – Paul H
    Mar 8 at 21:59
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    @Michael I compared the two tubes and found that both have small holes in essentially the same place. Even the side is the same. It seems to be more or less at the angle where the rim ends and the tire starts. I am trying to inspect the rim and tire but I can find nothing suspicious. I slide my hand or some cotton and nothing catches on. What should I be looking for? Mar 9 at 0:47
  • What shape and size are the holes? If they are slits it could be that you pinched them during installation or that you had a pinch flat (though the pressure loss would be great and quick in that case). Any rubbing visible? The “typical“ punctures from small, sharp objects are tiny and round.
    – Michael
    Mar 9 at 6:12
  • @Michael The holes are tiny and round. I think I found the culprit. The rubber got worn close to the side of the tire and the metal wire inside was a bit bare. It did not feel pointy to the touch but I guess it cannot be anything else. Thanks for the guidance, I am going to change the tire. I did not realize how imperceptible the culprit can be and how weirdly a tire with a small hole behaves. Mar 9 at 15:02
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Something subtle is in the tyre puncturing the tubes. It may be rubbing rather than piercing, and it may be imperceptible without pressure, but it's there. To help you locate it, align the logo on the tyre with the valve every time. Then when you find the hole in the tube you know where to look in the tyre (with some margin for error, and you might flip the tube over, so check the other side of the valve too).

As well as glass, wire, screws etc. I've had the threads from a nearly worn out tyre appear on the inside and cause slow punctures, and I've had the inner end of ice spikes wear holes in tubes.

Slow punctures are odd. They can seem to hold for a while then drop suddenly. Whether that's real or just that you notice suddenly, I don't know, but I've had a couple recently do odd things like that

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