Today, I checked my bike in transition for a race in the morning. I checked it in around 3:00 p.m., where it sat for the remainder of the afternoon in the heat of the day. Temperature at the race site when I left was 98*. Can this kind of heat do anything to a bike/cyclo-computer? I am particularly interested in my wheels – Renn rear ('03 model), Mavic front, both tubulars. I’m a little particular about my equipment; sorry if I’m asking a stupid question.
RP
I don’t much like leaving my bike out overnight, but you don’t get a choice in many cases. But I’d let some air out of the tires and pump them up inthe morning, before the race. It doesn’t seem possible, but I’ve hear tires (mostly clinchers, I think) blow in transition before the race start. Bummer to have to change a flat and get a 7 minute T-1. In any case, it costs you nothing and you should check them in the morning anyway.
Rest of the stuff should be OK, afik.
not a stupid question.
the main problem could be tires that blow in heat as the air inside expands…
otherwise the bike can take it
Yeah, I let some air out of my tires. Didn’t want to have a flat overnight. I really got to thinking about the heat messing up the construction of the Renn, and maybe compromising the glue on my tires/wheels. I figured everything SHOULD be alright, but hey, when a big race is looming you can start worrying about some strange things. Thanks to you guys for the quick replies.
RP
There was a tread awhile back debunking the myth of tires blowing. Some posted the formula for gases,came out to 4 lbs pressure for every 20 degree’s increase in heat. Or something very close.
maybe, but i have personally seen (heard actually–boom!!) it happen to bikes in tri transition areas…
I had my bike spayed, so it doesn’t go into heat anymore.
You already got good advice…a joke is the best I could add.
I had mine do it last year at CDA while sitting in my motel room. Found out it was a pinch flat. I was always told what you all were talking about also.Just going by the math posted. Not flaming you here though. I guess for a race though,let a little air out and have peace of mind,I worry about a thousand things before an IM.
Don’t ask how I know it was a pinch,guys at inside out told me. I also had a tire do it once and the tube had split by the valve,where it was folded during packaging. Another reason why I always put some miles on new tires and tubes before a race. Kenney
don’t worry about any flaming, i like to learn.
i would generally believe the math, but i think there is a problem with the scenario assumptions. dark or black tires SITTING IN DIRECT HOT SUNLIGHT might gain a lot more heat than the air temp would on a hot day (they would absorb a lot of heat by solar radiation), so they would inflate by a lot more than 4 psi or whatever. the result = BOOM!
I remembered that thread as I debated whether or not to let some air out of my tires. I almost didn’t do it, but I decided to err on the side of caution. No need taking an unnecessary risk, I figured.
RP
Here is the whole thread
If interested I posted that thread for Greg. Agreed. Before a race,may as well have peace of mind.
Interesting, but no good definitive answers in that thread. I have heard tires blow in transition areas at very hot races (typically after the bike leg). And another factor is a course with twisty downhills = braking which means even more heat build up.
I think the solar radiation is the crux of the problem. Air temp increases alone won’t cause problems. When was the last time you did a tri where the transition area was all in the shade? Me?–never.
“I had my bike spayed, so it doesn’t go into heat anymore”
And you’ve got a bike that should breed. Imagine what the puppies would be worth…
The science was very convincing. You’d think that road friction would heat 'em up more than sitting in the sun anyway, right? But my paranoia says don’t trust it, especially after hearing a few pop just sitting there. Besides, I always want to double check my tire pressure as close to race time as possible. You know, that old myth about natural rubber tubulars leaking…
Actually, mine always need air, even if they’ve only been sitting for a week.
“really got to thinking about the heat messing up the construction of the Renn…”
I have never heard of a tire blowing while going downhill. The heat causing the glue to heat up and the tubular roll off and consequently blow,but not just blow. If that was the case you would have tires blowing in the pelaton on every hot ride. The formula’s were there,what can I say?You can argue wiht physics if you like. If solar radiation is your concen,figure that in the equation.
Also,if you put 115psi in a Michelen Pro and it blew going downhill due to overinflation,Michelin would have been sued hundreds of times. Most tires can be pumped up to twice the rating before they blow. As far as tubes,you can put the same tube in a michelin with a top rating of 120 as a Verdenstein thats rated 140 or 145 and there are some tires that can be pumped up to 160psi(clinchers). For what you say to happen would mean that during a ride for a tire to blow you would have up to 40psi changes in pressure. Even when not blowing do you really think you tire pressures are fluntuating at even 20 or 30psi? Easy way for you to find out. Pump an old tire to 120psi,put out in the sun for an hr and check the psi. Or after a fast desent,brake get off the bike and check the psi.
Interesting, but no good definitive answers in that thread. I have heard tires blow in transition areas at very hot races (typically after the bike leg). And another factor is a course with twisty downhills = braking which means even more heat build up.
I think the solar radiation is the crux of the problem. Air temp increases alone won’t cause problems. When was the last time you did a tri where the transition area was all in the shade? Me?–never.
I’ve heard them go off in hot races and cold ones before (mostly) and after the bike legs… I think it’s new tubes getting pinch-flatted, not heat expansion.
don’t worry about any flaming, i like to learn.
i would generally believe the math, but i think there is a problem with the scenario assumptions. dark or black tires SITTING IN DIRECT HOT SUNLIGHT might gain a lot more heat than the air temp would on a hot day (they would absorb a lot of heat by solar radiation), so they would inflate by a lot more than 4 psi or whatever. the result = BOOM!
Greg/ORD,
You are exactly correct.
I was one of the participants in the thread on temperature and pressure change in tires. Your suspicion about radiant heat is a very valid one and something that was not considered in the temperature pressure thread.
Think of your car sitting in the sunlight with the windows rolled up. It may be 90 degrees outside, but it will be much hotter in the car. This is not all due to windows letting sunlight into the car. The sun can be somewhat overhead and somewhat behind the car so that very little sunlight is actually coming through the windows. The car still gets extremely hot inside.
Your bicycle tire sitting in the sunlight is much the same. The temperature inside the tire can rise considerably as a result of direct exposure in the sunlight. If you have been on any group rides on very hot days, you have probably seen or heard a tire blow at a rest stop on a bicycle that was out in the open in direct sunlight instead of under a tree or in some shade somewhere.
Just like when transporting your bicycle in your car and leaving it in a closed vehicle (like at work) for hours with the hope of riding it later, you should let out enough air to make the tires soft or spongy and have the means available to pump them back up before you ride.
This practice may be a little inconvenient and time consuming, but it is a lot less expensive and time consuming than changing and replacing tubes and tires. FWIW.