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deflating tyre......but no puncture?

Discussion in 'Technical Know How' started by handsome joe, 14 Apr 2008.

  1. handsome joe

    handsome joe New Member

    Do tyres have safety release valves? I placed a child seat (with child) onto the back of my Racer. I have Bontranger tyres - 200x35 and Specialized inner tubes. On our first journey i noticed after approx 15 mins my tyre had gone down quite a bit. I got off to have a look and it had almost totally deflated. I pumped them up again and returned home. At home i took the child off the seat and had to pump the tyres up again, thinking that i had a total blow out.

    That evening i had a look at the tyre again expecting to deal with a puncture but the tyre was still fully inflated? Can anyone explain to me what happened? Can tyres loose air if placed under too much pressure without having a puncture? By the way i have used the bike to and from work daily without any problems.
  2. alecstilleyedye

    alecstilleyedye nothing in moderation Staff Member

    Advert
    ghost puncture. i found my front tyre was down on saturday. had the tyre off and tube out, found nothing. put a new tube in to be on the safe side.
  3. hubgearfreak

    hubgearfreak New Member

    maybe there was something (grain of sand size) holding the valve O ring open?

    now you've blown it into the tube, or it's blown out:biggrin:

    nice feeling though, thinking you've got a P, but haven't:thumbsup:
  4. kyuss

    kyuss Senior Member

    Location:
    Edinburgh
    I had the very same thing happen today. Turned out to be a thorn that got pushed further in with the constant re-inflation and the pressure of riding home, effectively sealing the hole it created. Best to get the tyre off and check because it will eventually go.
  5. 02GF74

    02GF74 Über Member

    looking at a tyre doesn't tell the full story.

    you need to get the inner tube, pump some air into it a put it through a container of water - bubbles will show where the leak is.

    sometimes the hole can be tiny requireing a fair bit of air into the tube - it is quite scary how large the tube can get.

    Also often the valve stem where it is moulded to the tube can tear.

    After you have locate the puncture, you then remove the tyre and examine the inside for foreign objects.



    .... and yes, it is most annoying when a tyre keeps going dwon yet you cannot find the cause.
  6. Twenty Inch

    Twenty Inch New Member

    Location:
    Behind a desk
    Yeah, there's something in there letting the air out. Probably only became critical because of the extra weight.

    Take the tyre off and check it thoroughly, inside out. My last series of punctures was caused by a tiny sliver of metal in the tyre. With the tyre off for a regular post-puncture-repair check, nothing was evident. It could only be seen when I turned the tyre inside out. When I was on the bike though, the extra pressure pushed it against the tube, abrading a hole.
  7. Mortiroloboy

    Mortiroloboy New Member

    Did the rear passenger reach down and let the air out when you stopped at any point?
  8. Tynan

    Tynan Veteran

    Location:
    e4
    cometh the hour cometh the man

    he's right you know, tied the rear passenger up before putting them in the seat

    thread closed
  9. handsome joe

    handsome joe New Member

    Thanks for all the advice

    All, well most, of the advice is very useful. Will look into all these possibilities.
    Sorry Tynan for opening the thread again......don't spank me!
  10. Jacomus-rides-Gen

    Jacomus-rides-Gen New Member

    Location:
    Guildford / London
    Just replace the tube and inspect the tyre. Safety first and all that.
  11. bonj2

    bonj2 Guest

    I'm with mortiroloboy. Blame the child.
  12. Danny

    Danny Guru

    Location:
    York
    And as I've experienced you can sometimes put so much air in them trying to find the damn puncture that they explode - so do this away from your child!