Slow puncture or what?

gabriel959
gabriel959 Posts: 4,227
edited April 2009 in Workshop
Yesterday I was cycling along when I noticed that my rear tyre was a bit flat. I had pumped both tyres a week ago so something must be going on. I didn't see any sign of puncture or hiss that would give it away, nothing. Is there any way that a tyre could lose air without puncturing?

The tyre is an Specialized All Condition Armadillo and the tube a Specialized Presta one.

I arrived home and checked the gauge and it was down to 40PSI. I pumped it again last night but when I checked it again this afternoon it was down to 100psi (from 125psi I had pumped last night). Is that the sign of a slow puncture?
x-x-x-x-x-x-x-x
Commuting / Winter rides - Jamis Renegade Expert
Pootling / Offroad - All-City Macho Man Disc
Fast rides Cannondale SuperSix Ultegra

Comments

  • Smokin Joe
    Smokin Joe Posts: 2,706
    Yup.
  • C-S-B
    C-S-B Posts: 117
    its very likely punctured; had this happen to me a few times and as much as you hope its not a puncture, it probably is :(

    Take the tube out, making sure you remember which way it was orientated when mounted under the tyre. Inflate it a bit, and then pass the tube through a loosely clenched fist; if there is a hole you will feel the air against your hand. Some prefer to stick it under water and check for bubbles appearing but the above works fine and u dont need to find a puddle/ fill a basin

    Once you have found the hole, line the tube back up against the tyre orientated as it was initially, and then check the tyre for anything sharp.

    If you find something remove it, but if you dont it may just have fallen out.

    Pop a patch on it either way :)
  • Anonymous
    Anonymous Posts: 79,667
    My tyres seem to loose like 25-30PSI every week, I usually have both pumped to 115PSI.
  • crankycrank
    crankycrank Posts: 1,830
    Yup, as C-S-B mentioned, put the inflated tube in a tub of water and look for bubbles. If you don't notice any try moving the stem back and forth under water as well. Sometimes a slow leak developes at the base of the stem but will not be evident once the tube is removed from the rim. Moving the stem around will open up the leak.

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