Learned something new
 

I decided to take the road bike in to work this morning for a change since the weather is so nice so I checked it all over and pumped up the tires to the recommended 90psi and went on my way. I park outside of my building and the sun was shining on it this morning and both tires blew like gunshots. The tires came completely off the rims and both tubes are ripped to shreds. I have never had that trouble with heated tires on my lower pressure tires. I think the cycling gods are telling me to stop trying to use a road bike for commuting. LOL> Every happen to you?

I assume that by road bike, you are talking about the 77 Grand Prix? If so, does it have straight rims or hooked? If it has straight, then you can't go to the 90psi that your tires recommend. Being out in the sun wouldn't increase the pressure enough on a hooked rim to blow the tires off, but at 90psi on a straight rim, it would be barely holding on.

Its hooked.

hmmm... Unless the gauge on your pump is way off, or the tires weren't mounted right, the temperature difference shouldn't have been enough to blow your tires off the rims.

cannot tell how well the initial tire mounting was, did you go around the wheel

and insure there was no part of the inner-tube , visible under the tire bead?

that all the way around it was just between the tire bead wires, before ever inflating the tires?

happened to me. had a ross 10 speed i'd ridden from arvada to golden. parked outside foss drug
and while sitting on a nearby bench the front tube blew. was running 110psi and didn't think
the heat was that bad.

maybe just an aneurysm, snort!

there was a small bike shop open (on a sunday) in the alley around back
(bike propulsion) and i got a new tube there and the owner even put it on, no charge for labor. later that summer i rode into a tree and that was that for ~10 years- herniated neck disc.
when i was looking for another bike i remembered how nice the owner had been and went to that shop. i got my present bike there and a few
accessories and a couple of tools. she of course didn't remember me or the repair, but was appreciative of my long term memory!

we're ten years on now (total of 20), still have the bike, she's closed the shop and got into fitness writing.

I stand corrected. You are right, it does not have hooks, I was thinking of another bike. I got a ride home and took it apart and found exactly like you explain. I see it is straight. So now I'm wondering what pressure I should set them at.

I ride a road bike with a tire pressure at 110psi. I've had the rims so hot on descents that they literally hurt to touch. I did a tour once where a thermometer placed on the road surface was pegged at 150 degrees.

Both of those were on fairly large tours. I can't say nobody had a tire blow due to heat related issues, but it's not like we were hearing the "bang" of exploding tires left and right. It would take a hell of a lot of temperature change to change the pressure enough to blow the tire.

I guess it wasn't the heat then. I rode it 11 miles and parked it in the sun. Then I heard a very loud bang about 4 hours later. I looked outside and the tires were completely blown off and the tubes were ripped up. I repaired them and set it at 80psi. Hope that holds them. Time will tell. Not using it to commute anymore though. Going back to my commuter.

I recently blew my front tire on a long, very steep dirt road descent on a very hot day- in fact, it happened twice in a week. It was on my mountain bike with 26x1.95 Continental Gatorskins, which were mounted properly with one flaw. I had gotten a flat on the bike about a year ago and the rim strip had ripped and I had, as a quick on the trail repair, thrown in some electrical tape which I carry for emergency repairs of all kinds to serve as a rim strip. As I replaced the tube after the first blow out I thought, "Gee, I really ought to get a proper rim strip." After the second blow out I bought a good cloth rim strip and no more blowouts on that descent no matter what the temperature.

I wonder if the heat degrades the tire/tube strength, more than it being the pressure increase in high heat. Someone have a calculation of how much pressure increase could occur from heat?

Colder air is denser than warm. Maybe it was 90psi at that temperature when you inflated it, but turned out much more once the tires warmed and expanded. Happened on my father's car recently. I've had the reverse happen, where I inflated my tires outside when it was real hot and brought the bikes in (where my roomates keep it cold) and had what looked like low pressure issues.

M.

70 psi would probably be better for straight-sided rims. If you want to use higher pressures, try building up the rim bed with Velox tape that goes from one edge to the other (to keep the bead from shifting downward), make sure the tire is mounted evenly without pinching the tube anywhere, and experiment gradually with the pressures. :thumb:

I haven't had this happen on my vintage road bike yet, i run at 120psi. Though on vacation this summer i did over fill the tires on my cruiser bike by quite a bit.... long story short, people a few blocks away could hear the "gun shot", it literally tore the sidewall into strips. It was hilarious though because of how loud it was.... i didn't even mind walking my bike home.

Also just bought some vittoria zaffiro tires off jensonusa, they say they can run at a psi of 140.. should i do it?? haha

Sure, it's your bike. ;) Depending on the year, your "vintage" bike may have nice strong hooked rims that wouldn't have any trouble with 120psi.