Tubes going BANG!

sally65
sally65 Posts: 76
edited September 2010 in Workshop
hi
changed my tyres the other day and with in 2 minutes the rear blew.
thinking I may have put too much pressure in (unlikely) I tried again and it blew again in exactly the same place.
changed the rim tape and this time managed 35 miles before it happened for the 3rd time in a slightly different place.
these are 3" splits in the tubes. the 1st 2 were on the very inside of the tubes (6 o'clock if you think of it as aclock face) the 3rd 4" or so farther along and at about 9 oclock.
hope this makes sense.
the wheels are aksiums, conti tubes and gatorskin folding tyres. the 3 tubes alll came from different batches and the front has been fine.
Any ideas? its making me a bit nervous now as i do most of my riding to work at silly times, often after dark.
What arent I seeing?

Comments

  • John.T
    John.T Posts: 3,698
    It sounds as if you are not getting the bead seated properly. Partialy inflate the tyre and go round both sides making sure the bead is seated. Spin the wheel to make sure the tyre is running true. Then inflate fully.
    My Fleet.
  • Monty Dog
    Monty Dog Posts: 20,614
    Are you partially inflating the inner first? If not, it becomes trapped under the bead when inflated with the resulting bang.
    Make mine an Italian, with Campagnolo on the side..
  • sally65
    sally65 Posts: 76
    yes, did all that. could there be a problem with the tyre? the wall maybe? Ive looked but cant anything .And the splits are on the inside. why did the 3rd tube manage 35miles?
  • barrybaines
    barrybaines Posts: 273
    Sounds wierd but I have managed about the same mileage before and had the same issue, turned out to be as the above guys mentioned, if the tube is slightly twisted it would explain the position of the splits.
    I always partially inflate the tube and push the walls side to side to check its all sat properly, but on this occasion I must have just managed to get it caught under the bead every so slightly on final inflation. Then all it took was a small hole in the road causing enough extra pressure in the tube to go pop!
    http://www.justgiving.com/26-and-a-bit-miles
  • sungod
    sungod Posts: 17,411
    to go BANG the tube must escape the tyre, if it punctures entirely inside there's no bang, just a ssss

    either...

    bead not seated
    tube trapped between bead and rim
    split tyre
    faulty rim

    if the tyre was split i doubt it'd last 35 miles, so if the rim is ok that leaves the two usual causes

    if the tube is trapped, it can survive a quite while, but eventually it either fails internally and just deflates, or escapes past the riim/tyre and goes bang

    when replacing the tube, inflate it before putting the tyre back on the rim, put enough air in that it is just about filling the tyre, that'll stop it pinching

    don't use a tyre lever to get the tyre over the rim, but if you can't manage it with fingers, put some dilute washing up liquid on the lever/rim to reduce friction/sticking
    my bike - faster than god's and twice as shiny
  • sally65
    sally65 Posts: 76
    no I never use tyre levers to get a tyre back on. I always inflate a tad too.
    no splits in the tyre. its brand new which made me think there maybe a fault with the bead or something. not sure about the rim think its ok. I'll take it into LBS so another pair of eyes can see. No such problems with the old tyre.
    begining to think its because I said something rude about the pope.
    many thanks
  • desweller
    desweller Posts: 5,175
    Take a look at the rim braking surface. If it has failed it will be concave, rather than flat, which reduces its ability to grip the tyre bead.

    You might also find it useful to apply some talcum powder to the tube before you put it in, it will help it slide around relative to the tyre as it inflates.
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    On Strava.{/url}
  • sally65
    sally65 Posts: 76
    sorry to be thick.I built up the bike myself but I dont do rims.
    how can I tell if theres a problem with them ( say a small crack, too small to see)
    They've done around 7000 miles. is that a lot for rims?
  • desweller
    desweller Posts: 5,175
    7000 miles is quite a bit I would say, especially if they're done many winter miles.

    What wheels are they?

    Obviously, every time you apply the brakes, you wear a bit off the rim. The rim wall has to support the tyre pushing against it. Once the braking surface gets too thin, it can no longer support the tube and deflects when the tyre is inflated. This makes it unable to hold the bead.

    rim-wear1-300x279.jpg

    The bit the arrow is pointing at should be flat and parallel to the same surface on the other side of the wheel. This one is knackered.
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    On Strava.{/url}
  • sally65
    sally65 Posts: 76
    they're mavic aksiums and yes the 7000 miles does include winter weather. Some awful summer weather come to that.
  • desweller
    desweller Posts: 5,175
    You'll be able to see if the rim is curved by holding a flat edge against it. Got any pics?
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    On Strava.{/url}
  • sally65
    sally65 Posts: 76
    no pics. sorry cant do pics
    Ill get them checked out tomorrw. It seems like that could be the problem.
    Oh well, nothing lasts forever and if you say 7000 miles is alot then maybe its time to replace.
    Best replace both wheels I suppose.
    Thanks alot, you've been helpful.

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