The mystery of the Third puncture

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J1234 19 Apr 2021
  1. Schwalbe Marathon tyre, correctly inflated. Big vicious blackthorn
  2. Good quality MTB Tyre. Big vicious blackthorn.
  3. Brand new inner tube, did we nip it, was it a thorn.

Just had the autopsy, and when we removed the tube it was holding air, still had shape. However when we immersed in water it was leaking from the base of the valve, where valve and rubber meet. I suspect that if we had pumped the tyre up it would have got us back to the van (as it went down only 3 miles from the van, I left my wife and just returned to pick her up without mending the puncture)

So not really sure if it was a faulty inner tube from the get go, or possibly we damaged it putting it in, however as we had been quite rough with the valve repairing the Schwalbe, we had been very gentle with this valve, so that would be surprising.

Before we throw the faulty inner tube in the bin, people have mentioned having a bit of inner tube, what's that all about please. Its an MTB one so 2.5 or something.

Cheers Steve

 Dark-Cloud 19 Apr 2021
In reply to J1234:

I have had this failure before, sometimes the hole in the rim that the valve passes through isn't protected by the rim tape very well and can damage the seat of the valve if the hole has sharp edges, use a piece of old tube an inch square, put a cross cut in it and slip over the valve before you refit, this protects the valve seat

Post edited at 10:27
 CurlyStevo 19 Apr 2021
In reply to J1234:

I don't like those valves that have rubber coming half way down them as I've had issues before with these, I always get full metal valves.

Post edited at 10:31
J1234 19 Apr 2021
In reply to Dark-Cloud:

That could be the issue. We have checked the inner of the tyre with a tissue, and examined the tape protecting the tyre from the rim, and the tape was slightly mis aligned on the rim, though I did not recognise the potential issue as I was thinking ends of spokes.

 

 Dark-Cloud 19 Apr 2021
In reply to J1234:

It can be spokes but you would normally feel or see those coming through the tape, sounds like the valve hole from your description, just double layer tape it with electrical tape or use the tube method as i described above

 Hooo 19 Apr 2021
In reply to J1234:

Old or underinflated tyre?

A friend I ride with was plagued by tubes failing at the valve seat until I persuaded her to invest in some new tyres. 

 duchessofmalfi 19 Apr 2021
In reply to J1234:

A few of things come to mind:

- Rough handling in the field fixing the other punctures or nipping the inner when putting the tyre back - it's quite easy to do, especially fixing on the go.

- Sharp edge on the hole on the rim (fix by burnishing with a spoon)

- The inner tube got yanked when the other punctures occurred - basically an inflated tyre doesn't rotate wrt to the rim because it is pressed against the rim by air pressure.  A flat tyre can slip, the tyre and inner are usually stuck together (especially with a big thorn) so the inner gets dragged and this pulls on the valve.  Happened to me getting a pinch flat on a steep/fast descent braking hard.

- Just a shite inner (thin wall next to valve or dodgy metal fastening)

 Mouflon 20 Apr 2021
In reply to J1234:

A few years ago, I had a few punctures at the base of the valve and I put it down to two things.

First was roughness of the hole in the rim, as mentioned by others, so I filed it smooth then put some tape around the hole before refitting the inner-tube.

Secondly, I was using a frame pump where the pump itself clamped on to the valve. So whenever I pumped, it was moving the valve slightly against the hole, even if I tried to hold the pump & valve steady.
So I ditched that pump and since then have always used one with a hose.

 artif 20 Apr 2021
In reply to J1234:

I blame the tyres😋

After years of MTB including DH and quite a bit of road riding with barely a puncture, I set up a touring road bike with marathon plus tyres because of their puncture resistant reputation. Barely got a hundred miles on it and had three punctures, and they feel like I'm riding through treacle. 


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