There was a thread about something similar a week or so ago that seemed to end in much derision as I remember....but here goes.
I've got a second set of wheels for my Inbred for when I use it on the road. I used Schwalbe city jets on them.
I had what I thought was a slow puncture on the rear wheel so changed the tube and looked to repair the one with the hole in it. I couldn't find a hole, even after prolonged submersion in my pond (no formation of bubbles) so I put it down to not tightening the presta nut.....
The tube I put in then went down too over quite a long period.
I have taken the tyre off and checked for small pointy things embedded in the rubber, but am at a loss. I have used cotton wool pad things (nicked from her indoors) to see if the cotton wool catches on anything that I can't feel, but that didn't reveal anything.
I have also carefully checked the rim itself for sharp bits, but haven't found anything.
I looked at the tubes again and noticed that on one of them a tiny bubble of air escapes from the valve (between the stem & the presta nut) about once every 30 seconds. So this tube has gone in the bin.
But the other tube seems fine, but won't stay inflated when in the wheel.....
Next steps were gonna be new rim tape, new tyre & tube.......but before i do that, any other ideas??
Try a new tube - different type.
Rim nuts, rim rape etc won't do anything.
Its probably the valve - the lower pressures you will be using to check the tube off the bike should reveal holes in the inner tube, but may not be high enough to reveal faulty valve issues
Yeah - it would be easiest I guess to stick another tube in.
But, the first time I did this that tube also went down and I am a bit loathe to chuck another one in and get 'mystery deflation'.
Admittedly, one of the tubes seems to have had a dodgy valve, but it seems a bit weird that 2 tubes are deflating slowly on this wheel.....
Ho hum. Don't really like the idea of sticking another tube in until I've identified why the second one is going down, but as myopic has suggested, perhaps it's only at high pressures that a potential valve fault reveals itself.....
Inflate the tube to pressure in the tyre, on the wheel and stick the whole lot in your pond? It won't show you where any leak might be coming from the tube itslef, but you will see if the valve is faulty
Most tubes work, you've been unlucky enough to have 2 in a row with issues.
Seriously, just stick another tube in there, test the valve first if you want.
The other aspects you want to investigate/sort can cause punctures, but there's no evidence they did on this occasion.
If the tube is leaking at the stem base, you might be tearing it where the stem is bonded to the tube. Sometimes happens if the valve is not fitted perpendicular to the rim, or if the tube design allows the rim hole to put pressure on the joint.
myopic - yeah, I did debate doing that too......
c_al - yeah, you are probably right.....
kcr - doesn't seem to be any leaks at the stem base, at least not when removed from the wheel.....
Ta. I'll try another tube and see how that goes.
It's got........
Mavic depression.
Sorry.
Had the same thing with a bunch of continental tubes the valves were leaking at the joint with the tube. Leaks only showed up at high pressure.
It could be a very small hole which doesn't have a stream of bubbles when in the water. I've had it before, a very slight hole which a bubble forms on but takes a while to fully escape. A thorn only slightly coming through the tyre could be causing the problem.
Rusty Spanner - Member
It's got........Mavic depression.
Sorry.
😀
rob - Member
Had the same thing with a bunch of continental tubes the valves were leaking at the joint with the tube. Leaks only showed up at high pressure.
Think I will get a new tube and give it ago, before forking out for a new tyre and stuff...
Burls72 - Member
It could be a very small hole which doesn't have a stream of bubbles when in the water. I've had it before, a very slight hole which a bubble forms on but takes a while to fully escape. A thorn only slightly coming through the tyre could be causing the problem.
I thought this, but submerged each section of tube for ages....and saw no build up of air. The leaky valve I found this way - it took quite a while before a large enough bubble built up to detach itself....
Well. Stuck a new tube in last night, inflated to 60psi and it's still inflated this morning.....
😀
Told ya!