# Can leaving your bike in the sun cause a puncture?



## robing (22 Jun 2015)

In Spain at the moment, very hot! I'm at a hotel at the moment and bike not allowed in room so locked in courtyard. Generally pretty shady, but this afternoon the sun was on it and I thought about moving the bike or letting some air out of the tyres but stupidly I didn't. Anyway this evening I had a flat, small hole in side of tube, no foreign body, tyre fine. So I'm guessing the heating up from the sun caused the tyre to blow.

Is this likely, happened to anyone else?


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## robing (22 Jun 2015)

I have the tyres pretty hard but only with hand pump sowouldn't have thought I could overinflate.


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## Brandane (22 Jun 2015)

Bicycle? Sunshine? What is this rare phenomenon of which you speak?
<<<<<
I am not qualified to answer your question.


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## HarryTheDog (22 Jun 2015)

I had a MTB tyre explode in the back of my car in the sun with a slime inner tube, made a right mess, green gunk everywhere.


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## Fab Foodie (22 Jun 2015)

I've blown 2 tyres when they've been in the sun in the car. One time I was driving, frightened the carp out of me!


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## andytheflyer (22 Jun 2015)

From the general gas equation (IIRC) P1V1/T1 = P2V2/T2, since the T is in degrees Kelvin, going from say 293K to say 323K (a 30C increase) is not going to make much of a difference to P when V is a constant.

Not sure then that heating of a bike tyre in the sunshine (going from 20 to 50C) is likely to be the cause, unless the tyre was already inflated very close to its limit. But a better physicist than me can no doubt put me straight.


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## deptfordmarmoset (22 Jun 2015)

Yes, on a very hot day and the sun came round as the bike was standing and took the rear wheel out of the shade. I wasn't there when it went so I don't know how dramatic the rupture was.


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## Katherine (22 Jun 2015)

A few summers ago, we heard an explosion in the garage but couldn't find anything wrong when we went to investigate, until my son got out his bike the next morning to cycle to college. New tyre needed!


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## robing (22 Jun 2015)

Oh well. Easy enough to fix in the comfort of the hotel and not having to remove all the luggage from the bike. Fortunately bike shop down the road to stock up on inner tubes. It's my second already in a week! And new tyres on before I left.


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## Gravity Aided (22 Jun 2015)

Pavement can get pretty hot in the sun. I've heard of this happening with tubulars, but I was across the square when it happened,and ran to see what the noise was. I also had it happen on a tire that was a clincher, but believe I over inflated it. I had ridden about a mile on it when the tube exploded,also blowing out the tire.


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## Bodhbh (23 Jun 2015)

A couple of times I've come back to a flat after the bikes been in the sun all day. Both times I think it was friction holes cause by badly seated rim tape. So, I do suspect sun may push an inner on the verge of a flat over the edge. Temperature will soften the rubber too, so works on 2 levels?


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## jefmcg (23 Jun 2015)

I was stamping cards at the Ditchling Devil and there were a dozen or so bikes lying in the sun. This was about 140km into the ride. Suddenly there was a bang, and the back wheel on a Ribble was spinning, tube burst. 

I had assumed it was the sun.


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## Arthur (23 Jun 2015)

I also had a front tube go bang when the bike had just been standing in the sun for about an hour. Still, I'd rather it happen then than during a fast descent.


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## jay clock (23 Jun 2015)

a friend had one go in Mallorca at the half Ironman. Left bike in sun all morning in transition and when he came to bike out, it suddenly went with a bang. turned out the glue had melted on an old repaired patch. Taught him only to race with tubes that have not been repaired


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## andrew_s (24 Jun 2015)

A black tyre in the sun with no airflow can get pretty hot - maybe 75°C or more, which would give a pressure rise of 20% or so, depending on the inflation temperature. Even so, 130 psi isn't going to cause a puncture unless there's some other problem such as misplaced rim tape or a tube pinched between tyre bead and rim.


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## slowmotion (24 Jun 2015)

PV=nRT or something.

A black tyre in the sun can get too hot to touch but I doubt the delta V would be enough to pop it.
BTW, I think the T term is in Kelvins. Is that correct?


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## jefmcg (24 Jun 2015)

Yes, Kelvin.

If it was 10 degrees when you pumped the tyres up, and the tyres reached the 75C suggested above, the pressure would go up about 23%, say from 120 to 150 PSI.

That could definitely cause a blowout.


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## slowmotion (24 Jun 2015)

jefmcg said:


> Yes, Kelvin.
> 
> If it was 10 degrees when you pumped the tyres up, and the tyres reached the 75C suggested above, the pressure would go up about 23%, say from 120 to 150 PSI.
> 
> That could definitely cause a blowout.


 Not in a container that can expand flexibly, surely? V can change as the T and P rises, I think.


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## Gravity Aided (24 Jun 2015)

V has its limits, depending on material and deformation of container as T and P rise, I should think. Perhaps hence the bang.


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## robing (24 Jun 2015)

slowmotion said:


> Not in a container that can expand flexibly, surely? V can change as the T and P rises, I think.


The inner tube itself can expand, but not the tyre.


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## slowmotion (24 Jun 2015)

robing said:


> The inner tube itself can expand, but not the tyre.


Hmmmm... Good point.


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## Mark1978 (26 Jun 2015)

I've found that in my car, the heat gets up and the tyre get supple. The tube will then force the tyre off the rim, and with nothing to hold it in place will explode out of the gap created between tyre and rim.

For this reason, i now deflate my tubes if the bike is going to be in the car for long periods in the sun.


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