Phantom flat

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philvantwo
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Re: Phantom flat

Postby philvantwo » 30 Jan 2020, 12:12pm

Mines never blown off!!
Fact!
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Mike Sales
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Re: Phantom flat

Postby Mike Sales » 30 Jan 2020, 12:24pm

philvantwo wrote:The noise it makes is the air being released from the hose!


And of course, on refitting the chuck, the air in the pump cylinder and hose has to be compressed to a higher pressure than the air in the tube before pumping starts to open the valve and increase the tube pressure.
This applies to presta and woods valves: schraeder are designed to be opened by a touch on the central pip.
This can be observed by watching the pressure gauge. When pumping begins the reading rises rapidly until it reaches tube pressure, when the rise slows.

Brucey
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Re: Phantom flat

Postby Brucey » 30 Jan 2020, 12:46pm

There is more than one style of twinhead; if the wrong seals are fitted or a washer left out of the assembly, or something, it is possible that the seal won't compress enough to grip the valve stem.

On the other hand it doesn't take many goes with the head pushed too far onto the valve stem before the seal gets badly worn, either.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Mike Sales
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Re: Phantom flat

Postby Mike Sales » 30 Jan 2020, 12:50pm

Brucey wrote:There is more than one style of twinhead; if the wrong seals are fitted or a washer left out of the assembly, or something, it is possible that the seal won't compress enough to grip the valve stem.

On the other hand it doesn't take many goes with the head pushed too far onto the valve stem before the seal gets badly worn, either.

cheers


I hate to see the head pulled off the valve without the lever being released. It's a good way to wear out the seal.
The risk of this makes me wary of lending out my track pump, or indeed my Zefal HP.

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Mick F
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Re: Phantom flat

Postby Mick F » 30 Jan 2020, 1:35pm

philvantwo wrote:Mines never blown off!!
Fact!
What pressure do you use?

............. and is it one of these?
Screen Shot 2020-01-30 at 13.36.00.png
Mick F. Cornwall

philvantwo
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Re: Phantom flat

Postby philvantwo » 30 Jan 2020, 6:05pm

That's the one. Never had an issue with it so you're obviously not using it correctly, either that or you've stripped it down and plastered it in grease?
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Mick F
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Re: Phantom flat

Postby Mick F » 30 Jan 2020, 8:43pm

Ask again.
What pressure do you use?
Mick F. Cornwall

philvantwo
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Re: Phantom flat

Postby philvantwo » 30 Jan 2020, 9:23pm

120psi.
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Sweep
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Re: Phantom flat

Postby Sweep » 30 Jan 2020, 9:32pm

Only one way to settle this.

Grease guns at dawn.
Sweep

philvantwo
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Re: Phantom flat

Postby philvantwo » 31 Jan 2020, 5:39am

Or we could have a race across the old Forth road bridge!
:lol: :lol: :lol:
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Mick F
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Re: Phantom flat

Postby Mick F » 31 Jan 2020, 6:49am

:lol: :lol:

We used to live a mile or so from the northern end of the FRB.
Walked over it with Mrs Mick F and Daughter1 and Dog1 a few times.

As for cycling over it, they close the cycleway/pedestrian access without any pre-warning boards. Or should I say they've done it every time I've cycled over it 2006/2008/2010 .............. hopefully it won't happen again.

As for the Twinhead, try my experiment.
Connect and then disconnect repeatedly. Use a pressure gauge to check.
You will find that the pressure drops and drops and drops.
Mick F. Cornwall

PT1029
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Re: Phantom flat

Postby PT1029 » 31 Jan 2020, 7:36am

One question, what make of tubes are people using?
I generally aim for a more comfortable ride with 60 - 65 psi. My SKS* pump holds on fine for presta valves with theaded (for screw on collar) stems (Schwalbe) at these pressures.
When using none threaded valve (ie, so there is no thread for a screw on collar) the same SKS pump will sometimes slip off at 65psi. I'm talking of Michelin tubes here.
Similarly sometimes at work with Michelin/BTwin/Huchinson(?) no collar thread tubes with an SKS Renncompressor pump.
(*Home pump is a SKS Airbase that has had a charmed life at home).

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Mick F
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Re: Phantom flat

Postby Mick F » 31 Jan 2020, 8:47am

Vittoria Rubino Pro 23mm for me.

120psi in the rear and 85psi or so in the front.
The front is less fussy, but unless I get at least 120psi in the rear, there's too much tyre-drop.

Written on the sides of the tyres is min 100psi and max 145psi.
Mick F. Cornwall

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NATURAL ANKLING
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Re: Phantom flat

Postby NATURAL ANKLING » 7 Feb 2020, 10:51am

Hi,
The tip when using any type of pressure gauge is to over pump and estimate how much you lose each time you apply the gauge.
Otherwise you're not using the valve adapter from the pump correctly.
is Mick talking about losing air when applying the gauge or simply removing the valve head from the valve?
NA Thinks Just End 2 End Return + Bivvy
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.

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Mick F
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Re: Phantom flat

Postby Mick F » 7 Feb 2020, 3:14pm

NATURAL ANKLING wrote:is Mick talking about losing air when applying the gauge or simply removing the valve head from the valve?
I'm saying that ......... from experimentation ........... connecting and disconnecting and doing nothing else, will deflate the tyre.

Pressure gauges included in this, but the Topeak Twinhead was terrible.

The Lezyne Airbleed unit is foolproof and doesn't deflate the tyre.

............. from actual experimentation.

I repeat, the Topeak Twinhead was terrible. It worked well as a connector, but the unit releases air each and every time you disconnect and far worse than a good quality pressure gauge.
Mick F. Cornwall