Valve... whats going on?

[enc]

On yesterday's ride I had a blowout.

turns out the valve was slit close to where it joins the tube. i noticed the valve wasnt perfectly upright.

I replaced the tube (used but good condition) . On today's ride i noticed the valve had once again moved from its upright position.

I deflated the tyre, repositioned the valve and carried on. Back home i noticed yet again the valve has moved :evil:

WTF is going on?

 

[mk one]

The innertube is sticking to inside of tyre and its usually when you brake, but sometimes when you pedal hard, the tyre moves around the rim slightly pulling the tube around with it, the valve catches on the inside of the valve hole and cuts/rips it. You can stop it by adding a bit of talc inside tyre, also check inside valve hole for sharp edges though if you stop the tube dragging around the rim the valve wont move.

 

[mdvineng]

Re:

riding under inflated can cause that too!

 

[al-onestare]

^^^ as above and don't discount the rim tape. If it's worn or is coming loose it'll move the tube around.

 

[2manyoranges]

Creep...that's what it is.

Can be caused by a number of things, sometimes all happening together.
Loose tyre re beads. Could be just a 'relaxed' old tyre. Waiting to fail if it is...grrr. Ah...Specialised Ground Control - can be bloody loose on some rims....
Under-inflated, allowing tyre to creep on rim.
Failure to put talcum powder in when you replaced the tube - yep...talcum powder. Helps stop the inner tube binding to the tyre carcass.
Over-slidey, slick rim tape. This never seems to happen with the older fabric Velox tape.

This kind of creep can cause valves to split and blow, if the inner edge of the valve hole has not been filed smooth.

I'd try talc, since it's cheap. Just a handful in the tyre, then shuffle tyre round and round to distribute it. Then scrunch up inner and cover it with talc. Install as usual.
If that doesn't work, switch rim tapes.
If that doesn't work it might be time for a new tyre.....

Or.....simples....presta valved tube with indented locking which fits into schraeder hole drilling.....look at the presto locking ring here...it has a little lip the size of a schraeder hole...not all are like this....but this really works in stopping what you have experienced.

https://www.cyclesetsports.com/en/conte ... s-schrader

 

[rwm1962]

Another school day! I will apply those methods.

 

[enc]

The innertube is sticking to inside of tyre and its usually when you brake, but sometimes when you pedal hard, the tyre moves around the rim slightly pulling the tube around with it, the valve catches on the inside of the valve hole and cuts/rips it. You can stop it by adding a bit of talc inside tyre, also check inside valve hole for sharp edges though if you stop the tube dragging around the rim the valve wont move.

Thanks MK. we dont have talc but ill get some BTW, no sharp edges.

 

[enc]

Re: Re:

riding under inflated can cause that too!

I think this is definitely a major contributing factor... this only started to occur as recently, ive been running lower pressures due to riding very dry gravel tracks :facepalm:

 

[enc]

don't discount the rim tape. If it's worn or is coming loose it'll move the tube around.

good call... having re-checked ive noticed the hole for the valve in the rim tape is stretched and no longer round :?

 

[enc]

Creep...that's what it is.

Can be caused by a number of things, sometimes all happening together.
Loose tyre re beads. Could be just a 'relaxed' old tyre. Waiting to fail if it is...grrr. Ah...Specialised Ground Control - can be bloody loose on some rims....
Under-inflated, allowing tyre to creep on rim.
Failure to put talcum powder in when you replaced the tube - yep...talcum powder. Helps stop the inner tube binding to the tyre carcass.
Over-slidey, slick rim tape. This never seems to happen with the older fabric Velox tape.

This kind of creep can cause valves to split and blow, if the inner edge of the valve hole has not been filed smooth.

I'd try talc, since it's cheap. Just a handful in the tyre, then shuffle tyre round and round to distribute it. Then scrunch up inner and cover it with talc. Install as usual.
If that doesn't work, switch rim tapes.
If that doesn't work it might be time for a new tyre.....

Or.....simples....presta valved tube with indented locking which fits into schraeder hole drilling.....look at the presto locking ring here...it has a little lip the size of a schraeder hole...not all are like this....but this really works in stopping what you have experienced.

https://www.cyclesetsports.com/en/conte ... s-schrader

Thanks for the info