Bicycle Mechanics - here is a dumb question on tires

during the week i commute on my mountain bike. on the weekend i take long rides with my road bike (never use the road bike monday - friday). i ride my road tires at 115 psi. when i get home from the long rides on my road bike, and hang it up for the week, should i release the pressure in the tires? or just let it leak out slowly during the week? Or does it just not matter?

thanks for any answer.

during the week i commute on my mountain bike. on the weekend i take long rides with my road bike (never use the road bike monday - friday). i ride my road tires at 115 psi. when i get home from the long rides on my road bike, and hang it up for the week, should i release the pressure in the tires? or just let it leak out slowly during the week? Or does it just not matter?

thanks for any answer.


I vote for "doesn't matter". You mention losing air during the week. How much are you losing? Just curious.

very little. yet still enouph to have to put a little air in the next week

Circa 1970, I knew some cyclists who deflated their tubulars and hung their bikes on hooks after riding. I never knew anyone who did this with clincher tyres.

Doesn't matter.

I'm not sure why the tubular guys were doing that in the 70's, I rode on tubulars back then and I never deflated mine...even though I had plenty of guys tell me that I should. I had two sets of rims back in those days, and the one set (the racing set) would hang literally for a month sometimes and they were inflated the whole time...well sort of inflated, they naturally lost air due to the latex tubes and were flat by the time you used them again anyway.

No dumb questions, just dumb answers is the rule (AND NO I HAVEN'T SEEN ANY AS YET - but wait till you all read this post to judge.)
I have seen tires 'blow' when left in a car in HOT sun. Happened in Las Vegas Nevada Prior to a race, way back when (1972 - raced as part of a military team, nellis AFB), Tires were 'Full Up plus a few extra strokes' & awaiting for the start, we were registering. - BTW- had to wear gloves to handle the steering wheel till AC cooled it down some. Bet it got up to 180 F or so. Since then I always let out somne air if Bike is exposed this way, but I don't think a Garage would hurt anything.

Letting the air out then pumping it back up is a sure nice way to get pinch flats. Or at the very least increase the chances of it happening.

What on earth are you guys reading.

1. The laws of physics dictate that leaving fully inflated tires in the sun WILL NOT cause them to blow. If the temperature goes from 100 degrees to 200 degrees pressure goes up about 15p.s.i. If you saw tires blow it was from a different reason.

2. I have seen tubular tires get stretched out over time thats why air was let out fo them. The only clinchers I ever thought did this were some of the original michelins from the 80's.

To answer your question...doesnt matter.

1. The laws of physics dictate that leaving fully inflated tires in the sun WILL NOT cause them to blow. If the temperature goes from 100 degrees to 200 degrees pressure goes up about 15p.s.i. If you saw tires blow it was from a different reason.


Assuming they were filled with an ideal gas, I presume.

OK...so even if they arent filled with an ideal gas the pressure WILL NOT go up enough to blow them out. You seem to know a bit more about this than Boyle so please feel free to throw out the formula for us.

[QUOTE=miamijim]What on earth are you guys reading.
2. I have seen tubular tires get stretched out over time thats why air was let out fo them. The only clinchers I ever thought did this were some of the original michelins from the 80's.
QUOTE]

I've never heard a clincher exploding from heat (not saying it can't happen), but tubulars have been known to have their glue failed due to heat, but most of that sort of problem occured on fast mountain descents where someone was riding their brakes too much causing the rims to get super hot.

But a tubular will not stretch out more after the initial stretch. In fact with a new tubular you install it on a unglued rim a inflate it to full pressure and leave it overnight at least to stretch it initially, after that it will not stretch anymore; if they did then they would continue stretching if you rode on it everyday so that eventually the tubular tire would be no good. Also, most tubulars use latex tubes or superthin butyl tubes and both will loose air very quickly anyway. So releasing air from any tire before storing is a waste of time and an old bikers tale with no reasoning behind it.

Froze, I agree with you on the heat issue and tubular glue. As far as stretching of tubulars I understand the stretching of them on un-glued rims to facilitate the ease of glueing them. We pre-stretched thec more popular ones at the shop I worked at. At one point while I was a mechanic I measured the width of tires. some used tires were considerably wider tha new ones.