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I have a really frustrating problem on one MTB with the inner tube slipping round inside the tyre, which pulls at the valve and makes a hole. It's happened with old tyres (which we thought were slipping on the rim slightly) but also with new tyres. Mr Pea even glued the tyre to the rim but it happened again today. It happens regardless of whether I'm doing proper off road riding or pootling along tarmac.
We've wasted literally dozens of tubes. It doesn't happen on my other MTB.
Could it be the rims somehow? The problematic wheels are several years old and well used.
Any ideas?
http://singletrackmag.com/forum/topic/rim-keeps-ripping-valves-advice-required
talc is the other option so the tube grips the tyre..its on my winter bike so not tried any solutions yet
Also [url= http://singletrackmag.com/forum/topic/rims-slicing-presta-valves-off-at-the-base ]Rims slicing presta valves off at the base[/url]
and [url= http://singletrackmag.com/forum/topic/puncture-by-valve-stem-coming-out-of-the-innner-tube ]Puncture by valve stem coming out of the innner tube[/url]
It's obviously time to go tubeless
Talc is what works. Plenty of it.
It's not the tyre moving on the rim, it's the action of the circumference of the tyre when the tyre gets deformed during rotation. It puts some drag on the tube, but the inner surface of the tyre ratchets back (not literally, but that's the effect) so eventually the tube gets moved.
I have wondered if a grippy rim tape would help stop the tube getting dragged around, but no idea if it would make a difference.
I'd always assumed this was a pressure thing - it used to happen on my old commuter MTB all the time until I stopped just using a hand pump and got a track pump with gauge - and discovered that 20PSI or less was what had been passing my thumb test...
Low pressures that allows the tyre to move will definitely drag the tube around with it.
I think we're trying to nut out how it can move when the tyre doesn't.
I had this recently, changed the rim tape as it wasn't secured to the rim or very tight, has stopped the burst tubes.
Will also try the talc trick as well. Good tip.
When this happened to me it was down to an old tyre which started to move in the rim, e.g. when braking, and it was not until I saw that the plastic rim tape was scrunched up on one side of the valve by the movement of the tube against it that I realised what was happening.
It's not the tyre moving on the rim, it's the action of the circumference of the tyre when the tyre gets deformed during rotation.
If so, then there is more than one potential cause of these types of punctures at the valve stem, which is frustrating because it is potentially going to make it harder to diagnose the problem. That said, I am somewhat sceptical: all tyres on all bikes will deform during rotation, and even allowing for variation in tyres, tubes, rims, pressures etc., I would have expected a lot more punctures to be reported and ascribed by people generally down to this if it was a significant cause.
My suggestions would be:
- double and triple check the tyres and tubes (they are the correct sizes for each other and for the rim, and the bead is in good condition?)
- I would instinctively tend to use a highish pressure.
- I prefer inner tubes with threaded valves. This does not cure the underlying problem, but the locknut will stop small movements of the valve stem and keep it at 90 degrees to the rim. Possibly more importantly, I found that the cheap chinese inner tubes where the butyl extended up the valve stem were prone to puncturing as a result of the rubber around the stem being cut or abraded by the edge of the valve hole in the rim in the event of even very slight tube movement.
With regard to using talc to reduce the extent to which the tube moves with the tyre, I suspect that whilst this may help, there is still an underlying cause at work which needs to be identified, and talc (and similarly a threaded valve stem) only masks the underlying cause and/or delays the puncture.
It's not the tyre moving on the rim, it's the action of the circumference of the tyre when the tyre gets deformed during rotation. It puts some drag on the tube, but the inner surface of the tyre ratchets back (not literally, but that's the effect) so eventually the tube gets moved.
So glue the tube to the rim? Slippy rim tapes make things worse?
Try Velox rim tape and talc
Weird, so have you tried a larger tube ? What pressure ? Does the tyre fit the rim tightly ?
brant - Member
So glue the tube to the rim? Slippy rim tapes make things worse?
Only guessing.
On one hand a grippier rim tape may stop the tube moving back, on the other a slippery one allows it to move freely.
The answer is probably to stop the tyre's friction dragging the tube in the first place, which is why talc helps.
Ultimately a more reinforced valve/tube junction may be the best preventative.
Decided to go tubeless (with the help of mr Pea) and had not a single problem with tyres in 5 full days' riding in the Alps last week
🙂