Two tubes torn at the valve base in one day

curium
curium Posts: 815
edited March 2012 in Workshop
I'm still at work at 18:13 because when I went to get my bike the rear tyre was flat :cry:

This is my second flat today. I had one this morning that caused me to be late. I thought I was very thorough and checked the tyre for sharps but the tear was at the base of the valve stem.

This second flat is exactly the same. The wheels I have are Shimano RS30s. I've had them since August 2011 and not experienced this problem before. However, on closer examination the hole in the rim for the valve does seem to be wider than a presta valve so theoretically there is room for the valve to move which could stress the stem.

I have to use 48mm stems because the RS30s have a deeper rim than normal.

Is there a gromit I could fit around the valve hole to prevent any movement of the valve.

Could it be due to over-inflation? I run continental sport contacts 700c x 28mm. I usually pump them to 100 psi. The inner tubes are continentals also.

Anybody with these wheels suffer the same problem? Anybody got some useful advice?

Cheers!

Comments

  • curium
    curium Posts: 815
    Some googling suggests that this could be caused by the tyre slipping on the rim and taking the tube with it leading to the valve tear.

    Lots of tips about marking the tyre to detect if it is slipping but no info on how I can prevent it slipping on the rim.

    Anyone know how I can prevent the tyre slipping on the rim?
  • curium
    curium Posts: 815
    Some more googling gives me some possible solutions
    • Bit of Talc in tyre between the tyre and tube. Tyre still slips but doesnt pull the tube with it.
    • New tyre, either they dont fit your rims properly, or you've knackered the beading when you've fitted/removed them.
    • Wide Cloth rim tape - apparently holds the tyre in place better than plastic
  • curium
    curium Posts: 815
    OK I'm off home - On the train :cry:

    I'll return tomorrow armed with 2 spare tubes and some baby powder
  • keef66
    keef66 Posts: 13,123
    100 psi for 28's seems a bit high to me
  • benwils
    benwils Posts: 1
    Decent base tape and decent tubes should sort it out. Check the rim for sharp edges too.
  • harryquinn
    harryquinn Posts: 5
    Are the valves threaded all the way down and is your pump a push-on type with a locking lever?

    Every tube I've had with such valves has failed at the base eventually, because the threads grip the pump too much and make it difficult to remove. I only ever use tubes with smooth-stemmed valves now (Michelin Air Comp) and have never experienced similar problems with them.
  • Monty Dog
    Monty Dog Posts: 20,614
    What kind of pump are you using? Using a hand-pump can put a lot of pressure on the base of the valve and lead to the kind of damage you mention.
    Make mine an Italian, with Campagnolo on the side..
  • colinsmith123
    colinsmith123 Posts: 579
    Specialized tubes? Happened twice to me. Always carry 2 tubes and a puncture kit now. (Except at the moment where I only have one)
    Live to ski
    Ski to live
  • andy_wrx
    andy_wrx Posts: 3,396
    Are the tubes designed for 28mm tyres ?

    My wife's old Sirrus had 28's and when she punctured when we were out together I fitted a spare tube for 18-23mm tyres, which failed in the same way as you describe about 5 miles later.
    And then the next 18-23 tube failed in the same way again, another 5 miles later.

    I ended-up fitting a patch to her original punctured tube.
    Then bought some 25-35 bigger spare tubes...

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