Puncture or not a puncture?

alamo

Out this afternoon on first proper road bike (Triban3 which I've had for 3 weeks and love) but after 5 miles got a flat rear tyre. It seemed to lose pressure over a minute or so. Obviously had no equipment with me to re-inflate or carry out repair, so had to walk it home. There was no obvious foreign object sticking into the tyre so before removing the tube to look for the puncture, I inflated the tyre to 100 psi thinking that at that pressure I would be able to hear the air leaking to identify the area where the problem was. Heard nothing. Now some 4 hours later, the tyre is still fully inflated. I am therefore puzzled what to do next. Is it likely to be a hole in the tube requiring repair or maybe a valve fault? Why is the tyre still hard?

What should I do next, apart from carry a pump and repair kit when I go out?

simon_masterson

alamo wrote:

Out this afternoon on first proper road bike (Triban3 which I've had for 3 weeks and love) but after 5 miles got a flat rear tyre. It seemed to lose pressure over a minute or so. Obviously had no equipment with me to re-inflate or carry out repair, so had to walk it home. There was no obvious foreign object sticking into the tyre so before removing the tube to look for the puncture, I inflated the tyre to 100 psi thinking that at that pressure I would be able to hear the air leaking to identify the area where the problem was. Heard nothing. Now some 4 hours later, the tyre is still fully inflated. I am therefore puzzled what to do next. Is it likely to be a hole in the tube requiring repair or maybe a valve fault? Why is the tyre still hard?

What should I do next, apart from carry a pump and repair kit when I go out?

Leaving it overnight will show you just how slow a slow puncture can be, but easier is to do the lip test, and if that doesn't work use a bowl of water.

Have you checked the inside of the tyre, though? And the rim tape? You may not find the cause.

I'm up for being corrected, but I don't think it's the valve. I actually did once have a valve fail, but it would discharge all of the air very quickly (and with a noise I could hear back inside the flat!) within much less than four hours.

There's no excuse for not carrying tools when out, though!

AchillesLeftKnee

Not flatted on the road yet, but have had more flats off road than I care to mention, and in my experience the only thing to do is to get the tube off (you won't hear it with the tyre on unless it's a mega leak!) and play hunt the leak then, hopefully, fix the leak. Dinky punctures can appear to have disappeared when the tyre's not under load only to suddenly reappear the moment you give the tyre something to do. Also, a lack of obvious external damage is absolutely no indication of an intact tube.

alamo

I'll get the tyre off in the morning and put the tube in a a basin of water. Not had a bike like this before but would have thought that at 100 psi any leak would have been obvious. Never had punctures when I was a kid, but that was many years ago .... and maybe my memory is not what it was!

charlie_potatoes

If I was you I would replace the tube if I couldn't be 100% sure that I had found the cause.
You can get them for under £3 delivered so you may as well buy a spare at the same time.

Worrying about it going flat would spoil my ride

paultheparaglider

I had something similar very recently. The tyre went flat very quickly, and there was no obvious sign of a puncture when I checked it by the roadside. I pumped it back up and it then stayed up fine for the next 50 miles. When I got home, I checked the valve. It was a Continental inner tube that has removable valves, and the valve was slightly loose. Tightened up, and no problems since.

You are well advised to carry a pump and a spare tube on your rides. Punctures aren't that common with good tyres, but they do happen now and then, and rarely happen near to home.