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Puncture mystery

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Started 10 years ago by I were right about that saddle
Latest reply from gembo

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I were right about that saddle
Member

Right, who can explain this...

Yesterday I got a blackthorn puncture (the thorn looked like something out of a mediaeval crucifixion and need pliers to get it out of the tyre) which I fixed after work.

The next day...the tyre is flat. I pull it all apart expecting that the hastily applied patch has gone, but no, it's a new puncture next to the valve stem. So I fix that. I'm out of classic patches but I remember that I have a box of Park instant patches in my shorts so I slap one of them on and go to work. After work the tyre is flat...I kick the bike and use intemperate language in its regard. I apologise to the bike, take the tyre off and seek the new puncture in a sink of water. There is no puncture. I pump the tyre up and go home.

This morning the tyre is hard as a biscuit. No puncture. So...WTF?

Have I discovered the world's first quantum puncture? Are the fron and rear tyres in some sort of entangled state which collapses to flat only if observed? Has someone let my tyre down as a prank? I am properly confused.

Posted 10 years ago #
wingpig
Member

If air escapes without a puncture, assume something to do with the valve. I had a non-puncture mystery a few months ago where the valve occasionally leaked air it was resting upright, but was not detectable when the valve was half-way round where I usually put it when pumping it up and checking the pressure (where I can get my hand around the whole tyre to hold the pump nozzle in place), so it was only going soggy when I happened to stop with the valve in the right place.

Posted 10 years ago #
DaveC
Member

Sticky valve, perhaps wasn't screwed down tight? 'stuff' could have got in the valve and caused a leak, which when repumped dislodged the 'stuff'*

* Stuff, a TM'd term for debris etc...

Posted 10 years ago #
crowriver
Member

New tube. Sorted.

Posted 10 years ago #
kaputnik
Moderator

Insta-patch hadn't cured completely and insufficient inflation allowed a slow leak of air out of a microscopic gap. Pump up tyre again (harder) later on, squeezing the patch against the tube and tyre. Patch cures completely. Leak seals.

Posted 10 years ago #
I were right about that saddle
Member

@kaputnik

Liking it. I'd already put the adhesive on when I discovered I'd no classic patches. I let it dry totally (4 minutes 59 seconds, as ever...) before I put on the instant patch. Curing may have been retarded.

Posted 10 years ago #
DaveC
Member

Crowriver said "New tube. Sorted. "

Oh the opulence!!

You can tell those who live in the burgh....

Posted 10 years ago #
crowriver
Member

Hardly. Only ever owned four bikes from new. The rest second hand. None cost over £600 to purchase (as for maintenance costs, surprisingly little over the years).

Even Schwalbe inner tubes only a fiver each. What price your time spent in the rain trying to resurrect a flat by the roadside?

IMO if tube has a dodgy valve, best replace. Lengths of old inner tube come in handy for all kinds of repair jobs, frame protectors, etc.

Posted 10 years ago #
gembo
Member

@IWRATS what caused the puncture next to the valve stem? Sometimes if in a hurry I nearly forget to inflate, deflate, re inflate to ensure tube settled twixt wheel and tyre. But secondary loop kicks in in brain stem and routine gets completed. Maybees the tube is not optimal? I have a strike 1, strike 2, strike 3 and out tube rule now, though inspection of older tubes may reveal up to seven patches.

Posted 10 years ago #
I were right about that saddle
Member

@DaveC

I operate on the three patch/three year rule. Have done since I was an impecunious student.

These blackthorn episodes are making me long for the light grey solid rubber tyres on my first tricycle.

Posted 10 years ago #
I were right about that saddle
Member

@gembo

Dunno! Total mystery. It was on the rim-tape side and too close to the valve stem to be due to pinching or twisting. (I've always liked the resonant 'poing' of an inner tube untwisting itself on inflation.)

I'm seriously tempted by the notion of quantum tunneling being to blame.

Posted 10 years ago #
PS
Member

I'm with kappers on this. The only time I have had a slow puncture that suddenly cured itself upon re-inflation was with a tyre that had been repaired with a Park patch.

Posted 10 years ago #
gembo
Member

Schwalbe marathon plus with extra 5mm rubber and Kevlar now been totally copied by Panracer. Tyres look identical. Neither will stop blackthorn. You would think MOD would find a way of sticking the blackthorn on the ends of bullets?

Posted 10 years ago #
ARobComp
Member

I've had similar before. Basically what I reckon it is is that the patch doesn't stick quite right the first time but when you pump it back up it "takes" the second time. A bit weird but it happens. I've had it where the bike has been super cold and the tyres gone flat- pump it up and it's fine.

You might find that it goes down again in a week or so.

Posted 10 years ago #
kaputnik
Moderator

Uses for old inner tube #312.

Curing a noisy water tank valve which was sending a loud humming/vibrating noise throughout the whole tenement stair whenever the tank was refilling.

Crummy plumber had put the clip around the lagging (internal cold water pipe. why it was lagged I don't know!) and then nailed the clip in, rather than screwing. As a result the clip couldn't hold the pipe tight and support its weight, the piping was slipping down and stressing the valve, resulting in the strange vibrations and noises.

Solution: cut of the insulation, bung the gap between the pipe and the U-clip with a wrapping of cut-up inner tube, replace nails with screws. Screw clip tightly to the wall. Rubber grips the pipe but avoids it deforming.

Posted 10 years ago #
chdot
Admin

"IMO if tube has a dodgy valve, best replace"

+1

Or if puncture 'too' near valve base or anywhere with significant moulding marks/patterns/joins.

I have fixed a lot of tubes, quite therapeutic as well as cost saving - only costs 'time' money if you don't have anything else to do while waiting for glue to dry!

As I say to kids "what's the most important thing to remember about fixing a puncture? - what do you do after putting on the glue?*)

"Lengths of old inner tube come in handy for all kinds of repair jobs, frame protectors, etc."

Yeah, if I decide not to fix a tube I immediately cut off the section with the valve.

*I have had kids say 'put chalk on' - which explains a lot... In schools a lot of kids say they don't ride their bike because they've got "punctures". Often turns out they just have flat tyres and no pump.

'Most important thing?'

Four letters -

WAIT.

Well dried glue increases chance of patch staying on significantly.

No fun in rain/dark.

Carry a spare (or two) - or enough for a taxi!

Posted 10 years ago #
Roibeard
Member

I've an alternative theory if it was a Schader (car type) valve.

If the valve "pin" wasn't seated properly, the valve itself could have leaked, and it was seated properly on the second attempt.

As per my father's practice, I always put a blob of spit on a Schader valve post inflation to ensure that it isn't leaking - a bubble will form if is leaking. In 20 years I've been saved from a handful of flat tyres (bicycle or car) by this method, so the reseating issue isn't frequent, but is possible.

Shouldn't be an issue with Presta valves, but someone will be along in a moment to correct me...

Robert

Posted 10 years ago #
chdot
Admin

"Shouldn't be an issue with Presta valves"

That's true.

BUT sometimes some (types) unscrew.

Posted 10 years ago #
I were right about that saddle
Member

@Roibeard

I'm a Presta man. Never understood why Schraeder valves needed to come over here and take our valve seats. They never integrate either.

Just noticed that Greenroofer has had two punctures in two days as well...the plot thickens. He comes the same way as me.

Posted 10 years ago #
acsimpson
Member

With a presta valve it's sometimes possible to tighten it with the pin slightly squint. I don't know if that would cause a quantum deflation event or not though.

I always carry a spare tube plus repair kit. On the road I'll change the tube and then repair the puncture at home. The repair kit is in the bag mainly as insurance against Sod's law.

Posted 10 years ago #
Greenroofer
Member

I've had two punctures in two days in the same place on the same wheel with no visible cause. The puncture is a clean 2mm cut in the tube. I've inspected the tyre very carefully twice and can't find a culprit (and anyway, the tyre is a Marathon Plus, so I don't expect there to be a culprit).

It's never easy to do a proper check in a dimly lit bikeshed at work (Tuesday) or in rain at Meggetland (Thursday), so I took the other bike to work today and will do a proper check of the whole tyre, tube, rim, rimtape etc over the weekend.

There's something wrong. I just can't find it.

*Oh yes, and when I got home on Tuesday I found Mrs Greenroofer had a flat in her rear wheel which has hub gears and roller brakes and is a complete pain to remove. I had to fix that too.

Posted 10 years ago #
kaputnik
Moderator

I'm a Presta man.

Guy at work bought a German sit-up hybrid. It came with tubes with old-style Raleigh valves. He has a rather cumbersome-looking converter on them to allow use of a Schrader pump.

Posted 10 years ago #
MediumDave
Member

Re mystery punctures, I had a tiny sliver of metal embed itself in the tyre once. I could not find this with the tyre off the bike, no matter how much flexing or careful feeling around I did. The sliver was almost exactly the same thickness as the tyre itself which may explain its amazing camouflage properties.

With the tyre on, tube inflated and the bike unridden, all would be well. My theory is that when riding the bike the pressure of the road caused the little metal sliver to poke into the tube just one...tiny...little...bit and puncture it again. Its work done, it would disappear back inside the tyre again.

This mystified and enraged me in equal measure until the mystery metal popped out of the outside of the tyre after fixing the Nth puncture. Gah...

Posted 10 years ago #
I were right about that saddle
Member

Emerging themes;

Quantum punctures
Stealth punctures
Group punctures
Pseudo punctures

Posted 10 years ago #
Nelly
Member

Chap near Edinburgh Park Station the other evening was on (I think) his third puncture of the day, he had done all the right things, run his fingers round the tyre etc to find rogue bits of 'stuff' to no avail.

I asked if he needed anything, said he was fine, but he was patching.

I am of the lazy type - new tube every time, they are not that pricey, spend the money on decent tyres and one tube every year or so is a small price to pay.

Back on topic though - I reckon you have a valve flaw. I replaced a tube a couple of years ago and it exploded in the night - I remember running around the house looking for some reason for the huge bang - about 15 mins into the search I spotted the deflated tyre.

Couldnt work it out, thought daft throughts like 'its warm in the porch, the tube was in a cold shed....' but on reflection it was a flaw at the valve.

Posted 10 years ago #
acsimpson
Member

@Greenroofer. I had a similar puncture this week while heading along the A90 path. I stopped and put my spare tube on and checked the inside of my tyre. It lasted a couple of miles but punctured again before I got home.

I pulled a few bits of glass out of the tyre but nothing big enough that I would expect it to get through a gatorskin. Having patched and refitted the tyre was flat again by morning with a similar looking 2mm hole, although curiously not all the way through this time. I checked the tyre even more thoroughly and pulled out what I can only describe as sand from a few we nicks in the tyre. This time it seems to be OK and I made it into work today.

Posted 10 years ago #
Arellcat
Moderator

BUT sometimes some (types) unscrew.

For months I had this strange, very gradual deflation of my bike's rear tyre. I was convinced it was a tyre problem, a sort of micro-puncture like a strand of wire or something. I'd just give it a few goes with the track pump every other week and carried on as normal.

Last week I rode to work, and at hometime my tyre was flat. I quickly checked the tread and it looked ok, so I started pumping it up. I gave it a good go and the tyre just didn't seem to be getting very hard, so I gave it another go and it still wasn't anything like ride on-able. It must be a puncture! Pulled the tube out and pumped it up, except that I couldn't even get the tube to inflate properly. It turned out the Presta valve core had unscrewed itself because it came out attached to my pump.

So I put the core back in and tightened it with my fingers, tube back in, tyre back on, and started reinflating it. Damn it if I still couldn't get the tyre to inflate properly. It turned out my pump (Blackburn Airstik) was leaking air from the handle end, even though it was already fully tightened. By now I had wasted 25 minutes. I borrowed a handily-appearing colleague's pump, which did the job in double-quick time and sprinted into town to meet friends for dinner, for which I was now late. The next day I bought a new pump (Revolution mini track). I'll rebuild my Blackburn and keep it for backup.

Sometimes it's a thorn.
Sometimes it's the valve.
Sometimes it's your pump.
Sometimes it's a combination.

Posted 10 years ago #
chdot
Admin

"Presta valve core had unscrewed itself because it came out attached to my pump"

But it's so rare I've never bothered to work out if all/some/very few presta tubes have removable cores!

Posted 10 years ago #
I were right about that saddle
Member

The valve core was loose on the tube when I first fitted it. Came loose when I unscrewed the pump a couple of times, so I tightened it with extreme prejudice. Normally I don't tighten anything on a bike without using a torque wrench. Never occured to me to use one there...maybe I should have? Anyone know the standard torque on a Continental Presta valve core? I'll be proper impressed if anyone retains that figure in their wetware.

Posted 10 years ago #
Cyclops
Member

If you're having mystery punctures check the rim as well. Spokes or nipples poking through the rim tape can sometimes be the cause and I've also seen punctures caused by the join in the rim not being flush and smooth.

Posted 10 years ago #

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