How to find a reeeeeeeeeeally slow puncture

[mattheus]

I'm talking about the sort where you pump your tyre up, and you have to leave it 24h before it goes down enough to feel when you get on the bike.
Doesn't show up in the Bowl of Water test.

School me please!

[Jdsk]

Did you include the valve as part of the BoWT?

Jonathan

[Pebble]

I would have thought a 24 hour one would have been findable in a bowl of water. But I have had tyres that need pumped up once a week, in fact I have one at the moment, front one, needs some air added every week where as the rear one does not. - I have in the past investigated such leaks without success, just have to put it down as natural phenomena

I suppose if you sat starring at a bowl of water long enough a bubble would appear - it must mustn't it, can't just vanish into thin air, as per
that expression!

[rjb]

Occasionally a slow puncture eventually gets quicker when the previous repair patch comes adrift. Usually when it chucking it down and your 50 miles from home having forgotten your wallet and phone.

[hamster]

Having the bowl full of really hot water helps enormously.

[Paulatic]

How big is your bowl? Washing up size isn’t big enough.
Use an old bath or even a bath in the house or a minimum 45gallon drum. Blow the tube up so it’s so big it wouldn’t fit in a washing up bowl. Now tell me you can’t find it.

[roubaixtuesday]

Often I find these appear only when the inner tube diameter gets a lot bigger, presumably either because the pressure gets high enough to open the hole, or the stretch opens it.

My technique is every time you can't find it, pump up some more and try again, until the tube explodes, at which point replace it.

I've only lost one tube so far!

[Bmblbzzz]

Having the bowl full of really hot water helps enormously.

How does hot water help?

[slowster]

In addition to over-inflating, the other thing to do when the valve is submerged in the bowl, is put a finger on the top of the valve and wiggle it a centimetre or so from side to side. Small slits around the base of the valve and failures in the bond between the two layers of rubber at that point will sometimes not allow air to escape visibly/rapidly unless there is some movement of the valve.

[simonineaston]

Do some pump action a couple of times to focus on the error of its ways, then if no remorse is shown - Booof! New Inner Tube Time !! That's A Bingo...
Why? 'Cos life's too short.

[Grldtnr]

Often I find these appear only when the inner tube diameter gets a lot bigger, presumably either because the pressure gets high enough to open the hole, or the stretch opens it.

My technique is every time you can't find it, pump up some more and try again, until the tube explodes, at which point replace it.

I've only lost one tube so far!

If it goes 'bang' your sure to have found in it

[Mick F]

I have an issue with Schwalbe inner tubes.
Rarely get a puncture, but I have four tubes per bike as spares.

The issue with them, is that they have removable cores. Inflate your tyre/tube and tighten the Presta knob and fit the dust cap.
The problem, is that the removable core leaks.
You need a small spanner to tighten it so tight - very very tight - so it doesn't leak. The pressure can go down over a few days and it's impossible to detect it even in the kitchen sink.

Had I not "invested" in these tubes, I'd be a happier man.
Removable cores are the Devil's work.

[tenbikes]

How big is your bowl? Washing up size isn’t big enough.
Use an old bath or even a bath in the house or a minimum 45gallon drum. Blow the tube up so it’s so big it wouldn’t fit in a washing up bowl. Now tell me you can’t find it.

Use a plastic plant trough from BnQ........perfect! Not too massive, doesn't need as much water as a huge bowl.

[Stradageek]

+1 Mick, I've had the same problem. I tighten the removable valve before use... when I remember

[tenbikes]

I have an issue with Schwalbe inner tubes.
Rarely get a puncture, but I have four tubes per bike as spares.

The issue with them, is that they have removable cores. Inflate your tyre/tube and tighten the Presta knob and fit the dust cap.
The problem, is that the removable core leaks.
You need a small spanner to tighten it so tight - very very tight - so it doesn't leak. The pressure can go down over a few days and it's impossible to detect it even in the kitchen sink.

Had I not "invested" in these tubes, I'd be a happier man.
Removable cores are the Devil's work.

Odd. I have 24 tyres set up tubeless so with removable valves and they never leak, and I only do them up finger tight. Maybe you are compressing the seal?