I've just had my second puncture in a week - one in each tyre. I got a new inner for the front tyre as I've had the same ones since I got the bike and, needless to say, there were one or two patch jobs on them and with hindsight I maybe should have just got one for the rear as well and changed them both. When I was at the local bike shop for the tube, the chap mentioned getting loads of people coming in for similar replacements because of the warm weather and leaving their bikes in sheds which tend to get really warm, with this then leading to punctures. With the second tyre now having sprung a leak and knowing that the actual tyres themselves were free from any possible puncture-inducing thorns/glass etc, I was wondering if there might be something in what he was saying. Anyone heard of the hot shed tyre bursting gremlin?
CityCyclingEdinburgh Forum » Questions/Support/Help
Shed gremlins
(14 posts)- Started 11 years ago by gdm
- Latest reply from Smudge
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Posted 11 years ago #
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Suppose you inflated a tyre to 60psi when the air temperature is zero degrees (maybe you work in an industrial chiller unit) and then moved it to our greenhouse, which has been hitting 50C on a regular basis...
Gas law tells us that the tyre will hit a maximum of just under 71psi.
I was going to say it sounds unlikely to me, but I suppose if you take a large enough number of bike tyres and increase them all by 10psi, it's not impossible that a small number of them are already right on the verge of a flat and that 10psi tips them over?
Posted 11 years ago # -
I've been told many times that if you pump your tyres up to full pressure, don't leave the bike in direct sunlight for too long, as the heat causes the air to expand: exploding tube being the result.
Bikes that are left in the shed/garage for a while tend to lose tyre pressure anyhow. If your tyres are a bit softer, then I can't imagine the shed getting warm is going to do much harm. Only if you pumped your skinny road bike tyres up to the max in the cool evening before, then left in a sweat box shed/garage, could I see an issue.
Posted 11 years ago # -
Happened to me last week
http://cityexile.wordpress.com/2013/05/31/the-puncture-fairy-always-knocks-twice/
One shed puncture (I think it was the inner tube itself that failed as the hole was along the seam) - one patch then failed after I left the bike in the sun. I don't tend to have my tyres at massively high pressure, but I did have fairly old and much patched inner tubes
Posted 11 years ago # -
I'd wager it's more likely that either far more bikes that have sat in sheds overwinter are now out on the roads and previous slow punctures or damage now manifesting itself as flats. Or maybe warmed, softened tyre rubber more likely to soak up bits of glass from the road?
Or you've just been plain unlucky.
Posted 11 years ago # -
Cheers y'all.
I think Sally's line from her blog "more patch than tube" about sums up the situation for my long-suffering wheels. Think I'll invest in another inner and hopefully, given the new one I got for the front hasn't had a recurrence, that will be ok in the shed.
Failing that, I'll have to risk leaving the bike in the cat's room.
Posted 11 years ago # -
That could quite possibly be the reason for the couple of dramatic BMX blow outs I've encountered. I was up Stirling skatepark the other week and was just taking a wee breather in the rather hot sun. Some guy's BMX innertube literally exploded with the sound of a decent fire cracker.
I enquired to someone in the know on BMX bikes and apparently they do put their tyres up at massive pressures. This combined with the hot weather and black heat absorbing tyres could quite easily expand the air in the tube to breaking point.
The tube was actually shredded when it was taken out and discarded.
Posted 11 years ago # -
A tyre marked as max 70 psi that explodes at 80 isn't something I'd want to be running - talk about thin safety margins! I suspect what may be happening is that previous damage in the sidewall or bead has dramatically affected the strength of the tire with the result that even the slightest overpressure makes it go boom. In that circumstance even running it well below the max is still too risky as I could see it going boom at the slightest provocation (hello potholes..).
I recall Sheldon Brown saying that the lawyers want the max pressure kept low in case in the tyre is put on a weak rim, but the manufacturers want it high to make the tyre seem impressive, with the result that the actual max pressure probably bears little relation to where it would blow off. I've seen this myself, I used to have a pair of Michelin Country Rock tyres that were rated for 70 psi despite being literally paper thin on the sidewalls and just slightly thicker on the tread. So thin and flimsy I only got ~600 miles out of them before the casing split. I replaced them with a pair of Continental City Ride tyres of the same width that so far have done ~3000 miles with no flats at all. They're built like the proverbial brick outhouse with very thick sidewall and tread area. What's the max pressure? 56 psi. Not 60, 56...go figure.
On BMX tyres, the standard choice for park riding these days is the Fit FAF semi-slick. I have the 2.3" version and the max pressure is 110 psi. I can confirm from pumping the things up from flat that they hold an enormous volume of air and just getting them to 70psi is a chore. I can also confirm that being within 100m of a 110 psi BMX tyre blowout is likely to be the single loudest thing you ever experience. I can furthermore add that the combination of a 110 psi tyre and rim brake is going to lead to spectacular failure sooner or later.
Posted 11 years ago # -
I've witnessed tubes exploding over a number of years; there is some real rubbish on the market and, though I try to avoid that, I do sometimes wonder on a fast descent..........
Posted 11 years ago # -
allebong: "being within 100m of a 110 psi BMX tyre blowout is likely to be the single loudest thing you ever experience"
I did that in the small stone-walled bike store at a previous workplace. I was temporarily utterly deaf.
Posted 11 years ago # -
I was going to post a new thread along the lines of 'awful things I found at the back of my shed' but then I remembered the title of this one. I had to search for 'shed gremlin' and not 'shed gremlins' for some arcane reason, apparently gremlins doesn't seem to be indexed in the search while shed is.
Anyway, I was having a small clearout of knackered junk this afternoon, and had a look in a box I knew was mostly empty but I hadn't touched in some time.
Shall I let the pictures speak for themselves (best viewed at full resolution for maximum ick factor):
What I can identify:
-3 electric motors from old RC cars I've had, all burned out, or if they weren't they're certainly done for now, no idea why these are in here
-Several loose NiCad cells also from an old RC model. At one point since the cells were alright I was going to resolder them into a new pack, I think that plan is going no further. You can't even buy Nicads cells anymore, they were outlawed in the EU some time ago from what I remember, cue bloody eurocrats intefering with our right to get heavy metal poisoning etc.
-Various wires and a battery holder from my RC days. This must have originally been a depository for random spare bits, that was later joined by cycling paraphernalia. Half a V brake, bits of cable, a mudguard stay....
-Finally, that awful brown sludge that must have at some point been water. It'd be fascinating to send a sample off to a lab for analysis, see what's all floating about in it.
I've not actually done anything about it yet. Going to have to drain off the sludge, then sort out what else is lurking in there, can at least get the batteries off to recycling and throw the rest. Unless someone really wants that sprocket.
Posted 10 years ago # -
I'd wear rubber gloves if I were you: the crystals around that rear mech (?) look like battery acid related stuff. The bike bell looks salvagable.
Posted 10 years ago # -
Early 90s Schumacher, Allebong? Look like the silver anodised vari-shocks to me. Cougar 2? Shame about the Orion motor, though everyone's gone brushless these days.
Posted 10 years ago # -
Only tyre I've ever witnessed blow just due to heat was the front tyre on an audax bike after a loooong fast descent and then being left outside a cafe in the sunshine. Was good and loud, as was the 110psi road tyre that exploded next to me on a ride out, but I can do you far louder than exploding tyres ;-)
As with previous commenters my money is on 90% worn tyres/rims/tubes rather than any mysterious shed magic :-)Posted 10 years ago #
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