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Back Tyre Coming Off The Rim


jsyben94
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My observation was in the general, not particularly the current Sherco/Dunlop issue, context of tubeless rims and tyres where the pressure is the same as without a tube thus the tyre gets the same grip (designed to be airtight unlike a conventional tubed setup) on the rim as it would normally so security bolts are not a consideration?

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I'm not sure I follow your last post.

If you run a tube at 4psi without a rim lock on pretty much any tyre or rim make I would expect the valve to be torn off the tube. I can't guarantee this will always happen but I've experienced it and I've spoken to others with the same experience.

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This is in danger of becoming dragged out but, to explain my post.

The facts seem to be that some folk successfully use a tube with a tubeless rim and tyre and others don't.

We all know that, regardless of security bolts, a tubed tyre on a tube type rim does eventually creep and take the tube with it so we keep an eye on the valve and straighten things up every so many events.

As a tubeless tyre gets a really good grip on the rim, once properly blown on, it should not creep, certainly not any faster than a conventional tubed setup with its relatively poor grip on the rim.

The puzzle is, leaving aside faulty manufacture which normally is not the problem, why should some tyres happy at 4psi without a tube move so rapidly at 4psi with a tube that the rider does not get a chance to notice it and the valve tears out, but others stay put?

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I can only report on my own experience but this is that I've run tubeless tyres with tubes with no problem whatsoever on a Sherco then a Scorpa for about ten years. This has the advantage that the tyre stays at the pressure I set (no annoying marginal leaks where the tyre seals against the rim).

I've straightened up the valve on the rear perhaps twice in ten years of regular use, but it certainly wasn't near to "ripping out".

I too had my doubts about the reliability of running tubes in tubeless tyres until my local trials dealer, whose cheap tyre fitting service I took advantage of in a moment of laziness (I'd normally fit my own), advised me to do myself a favour by running tubes. His opinion was that unless my name was Michael Brown (it isn't) I wouldn't notice any difference in tyre performance (I haven't).

I normally run 3.5/3.75 psi in the rear.

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The thing I struggle with is why have tubeless technology (which we know works effectively) and compromise the principle by returning to tubes.. Surely the tyre/wheel manufacturers are compelled to ensure compatibility with current brands.

To me its unacceptable when riders are out at events on brand new bikes and they suffer component failure in an area that has established technology that proved good enough to supersede the tubed set up.

It is a different argument with older machinery and rims from earlier periods.

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You are right, it is not acceptable, but if a replacement tyre is not forthcoming, for whatever reason, then the tube offered is better than not using the tyre. Most trials riders don't want to get in to extended wrangling over consumer issues.

The more common reason was to cure the leaking spoke nipples on earlier rim designs.

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My observation was in the general, not particularly the current Sherco/Dunlop issue, context of tubeless rims and tyres where the pressure is the same as without a tube thus the tyre gets the same grip (designed to be airtight unlike a conventional tubed setup) on the rim as it would normally so security bolts are not a consideration?

 

A tubless tyre with a tube will not get the same grip as one without as you have introduced an extra spring.

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You are no doubt correct but, outwith the Michelin laboratory or unless ridden by a famous Yorkshire rider at the extremities of grip, how much is the extra flexure of 1.5mm of soft rubber really going to affect things for most riders (many of whom seldom seem to check tyre pressure anyway) in comparison with steady deflation due to leaky spokes?

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