Phantom flat

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Mick F
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Phantom flat

Postby Mick F » 25 Jan 2020, 6:33am

Out on the bike on Thursday morning for the first time in a fortnight.
Checked the tyres and added a few pumps to each.
Off I went, and home again. No issues.

Yesterday morning arrives and I saw the front tyre totally flat. :shock:
Ok, I thought, must've picked up a thorn or something on the way home and it's gone down overnight.

Front wheel off.
Good look at the tread and tyre walls. Nothing to see.
Tyre and tube off.
Good look at both, being very detailed in my looking on the inside of the tyre. Nothing to see.
Inflated the tube, and put it in the sink in the kitchen looking for bubbles. Nothing to see.
Left the tube inflated, and even added more air to it, and left it a couple of hours. It stayed inflated.
Put the whole lot together and pumped it up to full pressure 80psi. This was lunchtime yesterday.

It's still rock hard.
Dunno what caused the flat. Could have been the valve not seated properly, but as it's a Presta, it doesn't rely on pressure but the screw being tight ........... which it was.

Any ideas?
Anyone else had a phantom flat?
Mick F. Cornwall

Cavemud
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Re: Phantom flat

Postby Cavemud » 25 Jan 2020, 7:48am

This exact same thing happened to me last week.

Original tube still hanging over the door a week later with no sign of air loss.

Mine has a presta valve.

Could it be something to do with temperature or pressure change causing the valve to leak? (Mine had been travelling around Portugal in the back of the motorhome with fairly big temperature fluctuations between day and night)

peetee
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Re: Phantom flat

Postby peetee » 25 Jan 2020, 9:00am

At this time of year it’s likely that a bit of (wet) muck was caught in the valve when you pumped it up the first time. The tube was going down slowly and when you pumped again the muck was dislodged.
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Mick F
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Re: Phantom flat

Postby Mick F » 25 Jan 2020, 9:03am

We live in a bungalow and my bikes are in the spare bedroom, so nothing to do with hot or cold.

I favour the valve issue. It's the only thing it could have been. The thing about Presta valves though, is that they are screwed tight so it seems odd that it was leaking. It's the only thing it could have been .................. though odd, and never happened before to me.

Also, the bike wasn't used for a fortnight and the tyre was fine for all that time.
Mick F. Cornwall

David9694
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Re: Phantom flat

Postby David9694 » 25 Jan 2020, 9:24am

Any previous patches? they can do strange things some times.

I have had mystery flats - with the inflated tube Run past your face and then in water, you find nothing - put it in again and it’s flat next day.

I found one hole, the shape of which meant that it only leaked when you squeezed or stretched the Surrounding area.

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Mick F
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Re: Phantom flat

Postby Mick F » 25 Jan 2020, 9:26am

Yes, one patch. It was a first port of call to look at.
No leaks seen from it in the sink.

Tyre still hard nearly 24hrs later at full pressure.
Mick F. Cornwall

David9694
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Re: Phantom flat

Postby David9694 » 25 Jan 2020, 9:36am

With patches, I think the air builds up within and in water you can get one big bubble at 60 second intervals, rather than a continuous stream.

Sounds like back in it now goes, not pinching it on the way in, of course.

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Mick F
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Re: Phantom flat

Postby Mick F » 25 Jan 2020, 9:46am

Stop Press! :shock:

Just thought I'd measure the pressure by putting the track pump on ........... I don't have a separate pressure gauge.
I inflated to 80psi as usual, and the tyre still feels hard.

However, the gauge says just over 60psi!

Happy now! :D
Happy that it is a real puncture ....... or the patch of course.

I need to look very forensically now. If I can't find anything, the tube will be scrap and I'll fit a new one.
Mick F. Cornwall

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Mick F
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Re: Phantom flat

Postby Mick F » 25 Jan 2020, 10:12am

Valve! :D

Schwalbe with a removable core. With the tube out and pumped up, then immersed in the water, a tiny little trickle of bubbles could be seen coming out of the valve fitting where the core screws in.

It was tight, but I took it out, wiped the seal, then put it back in and tightened. (I have a small spanner that fits perfectly)
Checked again. All ok.

Refitted the tube and tyre, inflated to 80psi and I put the wheel/tyre combo into the water. No bubbles anywhere.

Solved.
Schwalbe removable Presta core not sealed properly.

Why do Schwalbe have removable valve cores? What are they for? Recipe for disaster, I reckon.
Mick F. Cornwall

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squeaker
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Re: Phantom flat

Postby squeaker » 25 Jan 2020, 11:01am

Mick F wrote:Why do Schwalbe have removable valve cores? What are they for?
Easier to get 'slime' and similar products in? Better engineered cores (albeit with the weakness you discovered)?
"42"

rjb
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Re: Phantom flat

Postby rjb » 25 Jan 2020, 12:52pm

I always check the valve core is done up tight. Who else has gone to pump up their tyre and removed the dust cap with the valve core stuck inside it. :oops:
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NATURAL ANKLING
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Re: Phantom flat

Postby NATURAL ANKLING » 25 Jan 2020, 1:57pm

Hi,
squeaker wrote:
Mick F wrote:Why do Schwalbe have removable valve cores? What are they for?
Easier to get 'slime' and similar products in? Better engineered cores (albeit with the weakness you discovered)?

Quite so, just like magic links, never use them, if you don't use either of them you will not lose anything :wink:
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Mick F
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Re: Phantom flat

Postby Mick F » 25 Jan 2020, 3:27pm

Mine are tight and always are.
I have a set of BA spanners.
The 7BA end of the 5/7 fits very nicely.

The one that was leaking was tight. Should I say it was tight to undo?
Either way, it was removed, cleaned off, and re-fitted and tightened.
The Schwalbe tubes are good tubes .............. maybe let down by the removable cores.

As for getting slime in there, why do other inner tubes not have removable cores?
Mick F. Cornwall

Marcus Aurelius
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Re: Phantom flat

Postby Marcus Aurelius » 25 Jan 2020, 10:09pm

Check the rim tape. Any breaks above the spoke holes or herniation of the rim tape at the spoke holes can cause this sort of thing.

philvantwo
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Re: Phantom flat

Postby philvantwo » 26 Jan 2020, 12:13pm

Continental innertubes still have removable cores.
Years ago when deep section rims first came out you had to use valve extenders as long valve innertubes didn't exist. You'd take the core out, wrap some ptfe tape on the thread of the innertube body and then fit the extender, finally fitting the removable core in the top of the extender.
I'm surprised that mick f's valve was leaking as I read on here that he strips his bike down every 2 months and checks and greases everything with a thread on it!
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