CityCyclingEdinburgh Forum » Questions/Support/Help

Tube troubles

(23 posts)
  • Started 9 years ago by Murun Buchstansangur
  • Latest reply from davey2wheels
  • This topic is resolved

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  1. Murun Buchstansangur
    Member

    Hopefully the CCE borg mind can help me out.

    I'm having trouble getting the front tyre on my commuter to stay inflated. Woke up to a flat last Wednesday morning, so I swapped out the tube for a cheapie replacement I had from Planet X (Vavert is the make) and set off to nursery then work. Seemed fine but at the end of the work day, I returned to another flat, which caused a problem for nursery run - had to leave the bike.

    Next day I returned to work with my other Vavert spare, which got me home OK. Friday morning, another front flat! Not a nursery day, so I took the road bike.

    At this stage, I was cursing the Planet X tubes, so wandered down to the Bike Co-op and picked up a Specialized tube (all they had). Initially, I thought that had solved it, but my other half borrowed the bike to go to the gym last night and on her return, the front was audibly deflating.

    Am at a loss as to what is causing this - dunking the first 3 tubes showed no leaks at modest pressure, on the couple of occasions it has been possible to hear a leak, it seems to be from the vicinity of the valve area. Have thoroughly scanned the rim & inside/outside of the tyre both visually and manually for a cause on several occasions, to no avail.

    Don't think I am pinching the tubes on the way in or over-inflating them - usually I run at 70psi (anything more and the tyre fouls the mudguard). Since this started have gradually dropped to inflating to 50 just in case. Rim is a Alex Rims XD-Elite & tyre is a Continental Speed Ride 700x42.

    At this point, any suggestions gratefully received. Am rapidly losing confidence in using said bike to transport a small passenger just in case...

    Posted 9 years ago #

  2. SRD
    Moderator

    is it possible your pump is somehow bending the valves?

    (I'll let the real experts takeover now...)

    Posted 9 years ago #

  3. deckard112
    Member

    Have you fully inspected both the tyre and actual wheel rim inside and out? I had a similar issue with my mountain bike and after going through five tubes (and despite inspecting the tyre) I discovered the braking rim had a very small metal nick which was cutting every tube I put back in. Sanded it down a little and no issues since. It doesn't take much.

    Highly recommend a forensic examination of both!!

    Posted 9 years ago #

  4. Snowy
    Member

    I'd persist with dunking the tube in the bath. The air's got to be coming out somewhere. I had a minuscule slow puncture which only produced one tiny air bubble every minute or so - but it was enough to flatten the tyre overnight.

    When you take out a flat inner tube, put a pen/chalk mark on the tyre, rim and the tube at the same point so they all match up. So, when you hopefully find the leak, you can go back to the rim and the tyre and inspect that precise location much more closely.

    Posted 9 years ago #

  5. Murun Buchstansangur
    Member

    Hmmm, the valve point is possibly a good one - I always use a flexible connector tube before connecting to the pump, as my track pump is rather hard to attach otherwise.

    deckard112 - I intend to have yet another look when I get the latest tube off later.

    snowy - another good suggestion which I will follow up later.

    Posted 9 years ago #

  6. kaputnik
    Moderator

    I've experienced where the the pump-it-up-and-hold-it-under trick doesn't always locate tiny nicks in the tube, which require the weight of the bike (and rider) pushing down on them and then releasing as the wheel goes round to work the air slowly out, then comes a point where there's not enough internal pressure to force the air out so it seems to stay semi-inflated.

    Forensic inspection with fingertips and eyes can usually and eventually locate a tiny bit of sharp rim or something embedded in the tube.

    When you take out a flat inner tube, put a pen/chalk mark on the tyre, rim and the tube at the same point so they all match up. So, when you hopefully find the leak, you can go back to the rim and the tyre and inspect that precise location much more closely.

    For road-side changes, it can be worth being anal about lining up the lettering on the tyre sidewall with the hole for the tube in the rim. Of course you might accidentally flip the tube over, but you can accurately estimate from the position of the offending item two possible positions where you need to patch a hole in the tube.

    Posted 9 years ago #

  7. wingpig
    Member

    I've had a couple of valves where the sealing around the valve base was dodgy, but only in certain positions/high pressures/when the valve was waggled, so they didn't show up in bath tests. I've had a couple of (Presta) valves where the screw-in bit wouldn't seat properly, resulting in it loosening then waggling itself undone, whereupon it could then gradually deflate when the tyre was resting in the necessary position.

    Posted 9 years ago #

  8. Murun Buchstansangur
    Member

    kaputnik - I've had that kind of frustrating self-stopping p*nct*re before, but currently every tube so far has gone flat as a pancake. Which makes it even more surprising I couldn't find anything underwater...

    Lining up brand and valve is good advice, which I follow. Should be in The Rules!

    wingpig - my working hypothesis is that this is a valve problem. They are Prestas, should have mentioned that.

    Posted 9 years ago #

  9. steveo
    Member

    http://www.velominati.com/the-rules/#40

    Posted 9 years ago #

  10. earthowned
    Member

    @Marun - I've had a similar problem with overnight deflating tubes for ages. After going through 3 or 4 tubes I finally twigged the tubes were leaking from the same spot, but couldn't see any corresponding sharp burrs on the inside rim. Something must have been rubbing so my solution was to cut out an old bit of inner tube and put it in the offending place. Seems to have worked so far. I'd be really interested to find out what the cause of your problem is!

    Posted 9 years ago #

  11. I were right about that saddle
    Member

    All of the above, plus...it's worth splashing out on decent rim tape, like DT Swiss. That plus eyes-closed fingertip examination of the rim and inner surface of the tyre should get to the bottom of the leak.

    Posted 9 years ago #

  12. Murun Buchstansangur
    Member

    @steveo - thanks, I thought it was in there - actually, I did check, but searched the page for tyre, not tire. Bloody colonials, grumble, mutter

    Posted 9 years ago #

  13. steveo
    Member

    Yeah they need to add spelling to their bloody rules!

    Posted 9 years ago #

  14. minus six
    Member

    on the couple of occasions it has been possible to hear a leak, it seems to be from the vicinity of the valve area

    slow punctures near the valve are generally caused by over tightening the valve nut.

    if you do, then don't - just leave it loose.

    Posted 9 years ago #

  15. Murun Buchstansangur
    Member

    Well, it *might* be solved

    Found a very slow puncture on the outside of a couple of the tubes in pretty much the same location (c. 3" from the valve) by leaving them submerged for a period. Crossreferencing to the tyre, I then found a very small flint (<1mm) that had escaped my notice as it was dug in right by one of the tread patterns. Still couldn't feel it from the inside, not even that sharp once removed, but possibly a different story once loaded with 90kg of bike & rider. Anyway, it's now gone, one of the 4 tubes repaired, fitted & inflated and I guess I will see at the end of the day if that is the end of the matter...

    Posted 9 years ago #

  16. gembo
    Member

    The tension is mounting

    Flat or no flat?

    Posted 9 years ago #

  17. Murun Buchstansangur
    Member

    Yep, appears to have been a very slow p*nct*re. Now have another 3 tubes to patch!

    Thanks everybody for the very helpful suggestions.

    Posted 9 years ago #

  18. UtrechtCyclist
    Member

    Hi all, I'm having tube issues...

    On Monday evening ride home my back tyre was feeling a little flat. By Tuesday morning it was almost empty, but I was late for work and so I just inflated it and rode to Waverley. After an hour on the train it was a little flat again and so I inflated again for the ride from Leuchars to St Andrews, which it did fine for. Time to ride home and it's flat again so I inflate it again and come home. It felt like there was air coming from the valve, but I didn't have time to check.

    Since then it has managed to keep it's pressure for the ride home, and on the train, and overnight. Previously it had been losing pressure quite quickly, but now it's stayed completely inflated for twelve hours including an hour of cycling.

    I think I know the answer, but is there any chance that there was a problem with the valve that has just solved itself? Presumably not, but I feel pretty stupid walking into a bike shop and complaining of a puncture when my tyres are rock hard...

    Posted 8 years ago #

  19. Roibeard
    Member

    A Schrader valve (car-style) can sometimes not "seat" properly. My father taught me to always check with a little spittle (bubbles) prior to doing the valve cap.

    Although I do this as a matter of course, I've only ever had it save me from a flat on a couple of occasions!

    Simply flicking the valve pin with a fingernail had been enough to seat it properly.

    Robert

    Posted 8 years ago #

  20. Nelly
    Member

    I had one recently with similar issues, I didn't bother changing it out and then it gave up the ghost on a rainy evening - karma.

    I kept the old tube and determined that it was flaws in the - no doubt cheaply put together - welds around the valve.

    These were tiny pinpricks and I can only surmise, based on their location, that high pressure 'locked' them against the tyre, but when they lost a little pressure after a few days commuting they started to let out air.

    At least that's what my theory was, may be complete BS !!

    Posted 8 years ago #

  21. kaputnik
    Moderator

    Simply flicking the valve pin with a fingernail had been enough to seat it properly
    There's normally a little raised bump in the middle of the cap that can be used to pop the valve head just enough to seat it.

    Posted 8 years ago #

  22. UtrechtCyclist
    Member

    Thanks! Hadn't heard of valves not 'seating', but I'm hoping that was the problem. I'll try cycling around for a few days with a pump in my pannier just in case.

    Posted 8 years ago #

  23. davey2wheels
    Member

    Not mentioned but if the tube has a presta valve with a removable core, check that the core is not loose.

    Posted 8 years ago #

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