The Phantom Puncture

[dhd.evans]

I have been beset by punctures recently, but this one has me really confused.

I'd put too much pressure in the tube (presumably) and when I hit a slight bump the seam on the tube burst, about an inch or so. I took the tube out at work, pumped it up to hear where it was (on account of the big bang, rapid tyre deflation presumed it'd be a big 'un). Found the blighter, repaired it.

Now, this is where it gets a little funky.

Cycling home on it it starts to deflate slowly. I presume the patch isn't completely sealed so try the 'pump n' dash' method. Doesn't work, it still deflates. I'll add that I had to force the valve slightly to accomodate my rigid pump (giggedy). So I shackle the bike up to a post and head home on the bus.

Once home with the bike I start to strip the wheel and tube completely, as per the usual when i've got all my tools and things! Pump it up, run it through the basin of water.... no air escapes.

"Fair enough" thinks I.

Check the rim, all accounted for nothing to prick the tube. Check the tyre, and ditto.

"Right, that's weird..."

Pop it back together, start pumping the tyre up.

**hiiiiiiiiiiiiiiiissssssssssssssss**

"What the frak?!"

This is a LOUD hiss.

Tyre popped, tube out, basin of water filled, tube through it.... no bubbles. I'm scratching my head here, physically scratching it looking quite puzzled. Tube out, back in wheel, tyre over, pumped up.

**hiiiiiiiiiiiiiiiissssssssssssssss**

"What the frak is going on"

I've abandoned my bike this week in favour of doing some running because this is driving me around the bend. Anyone got ANY ideas?!

 

[akb]

Could it be the pump adapter? Maybe that is leaking?

If not, I am just as confused as your are!

 

[Hip Priest]

A similar thing happened to me.

Then I realised the hissing sound was the handle on my track pump going back down. I hope you're not as thick as I am.

 

[PeteT]

Valve?

 

[akb]

Valve?

Thats the word!

 

[Night Train]

Just wondering....

I put tubes into my wired car wheels and have to let the air out from between the tube and the tyre as it is inflated. If not then the tube holds trapped air in the tyre carcas by pressing the valve into the rim hole. Otherwise, as it rolls, the flex in the tyre and tube lets the air out of the tyre allowing the tube to fill out resulting in a a sound tube but with relatively little air in it!

I found a similar thing with one of the Schwalbe Marathons on my Brompton. I had to pinch the tyre around the rim to let the air out from between the tube and the tyre as I was trying to inflate it.

I know that when refitting the tyre the tube should have some air in it to fill the tyre but one of my tubes was the wrong size and wouldn't go on inflated. That left air trapped in the tyre outside the tube.

 

[dhd.evans]

I found a similar thing with one of the Schwalbe Marathons on my Brompton. I had to pinch the tyre around the rim to let the air out from between the tube and the tyre as I was trying to inflate it.

I don't quite understand what you're meaning, but I am using Marathons for the first time on the rear wheel. There is a definite 'pocket' of air bulging at parts of the wheel. Could this be the solution? Will check tonight.

As for the others... I think it might have something to do with the valve, but this hiss comes from where the puncture has been repaired and is nowhere near the valve.

I are quite confuzzled.

 

[Night Train]

I don't quite understand what you're meaning, but I am using Marathons for the first time on the rear wheel. There is a definite 'pocket' of air bulging at parts of the wheel. Could this be the solution? Will check tonight.

The tyre was really, really tight to fit and so it sealed it self to the seat trapping air between the tyre and the inner tube.
Some of the trapped air did leak a little at various points around the rim making little pffftttt noises as I pumped the tube up so I had to unseat the tyre a couple times to let the air out so the tube could fully inflate inside the tyre.

 

[steve52]

ear plugs!!!! then ya cant hear the hiss simples

 

[dhd.evans]

S'the valve.

Bastard puncture. Pumped it up again last night, no let out. Put it on the bike, cycled 3 miles, flatter than Keira Knightly's chest!

To add insult to injury my front tyre has just done a collapse too. Bike abandoned in an unfamiliar area (love it!), bus to work in full lycras.

New inner tube at the weekend.... again...

 

[tyred]

What type of valve? You can swap Schrader valves around very easily.