Tire Pressure Issue

[Mr. SR500]

It's losing too much air. Try a different brand of tube or another new. Currently my rear tube will hold pressure, only losing a couple psi a day, but the front will lose about twice as fast and it gets inflated to lower psi.

[Tri Girl]

I've wondered about this myself. I rode my tri bike on Tuesday and pumped the tires up to 135 (the rec. inflation is 130-160). Yesterday I get it out to ride and it's down to 120. Who knows? I just consider the pumping my pre-ride warm up.

[Tuckervill]

I'm no scientist or anything.

Shouldn't there come a point when the tube is under pressure that the interstitial spaces are too small for air molecules to go through?

Thus they would never go completely flat. The curve would end at some point.

I can imagine a manufacturer would try to perfect their product to balance between the natural properties of the rubber and the amount of stretch at pressure that increases the size of the interstitial spaces.

Anyway, that's my thought experiment for the day.

Karen

[Mr. Bloom]

I'm no scientist or anything.

Shouldn't there come a point when the tube is under pressure that the interstitial spaces are too small for air molecules to go through?

Karen: Such big words! Are you sure you're not a scientist?

ehirsch: My tires are 100 psi. bikeleague training says not to overfill, so I don't (although I used to...)

The bikeleague training also says to check air pressure before each ride. I do since I'm alone during the week and don't have many to call for help if I get a flat and get stuck out past dark.

[kiwi girl]

I'm only riding my road bike on the weekends at the moment. My tires seem to go down from 120 to 80 or even less over the course of a week - but I agree with the slowing down of the rate of loss theory - after a couple of months they haven't got much below 50.

Note to self - pump up the tires on the commuter.

[sundial]

Mr. Silver, is there a chance you have a bad batch of tubes? Our LBS had cyclists coming in by droves with flats. I believe the bad batch of tubes were Specialized. They switched to Bontrager and it reduced the incidents of flats.

I had something weird happen not long ago. I purchased new Specialized Captain tubeless tires and it would go completely flat over night. The bike mechanic took soapy water to it and air bubbles developed all along the sidewalls. Needless to say I switched tires.

[redrhodie]

Am I the only one who pumps before every ride? It's part of my pre-ride ritual. If I didn't do it, I think I'd feel like I forgotten to brush my teeth.

Okay, I admit it, I'm a little like Monk.

[SouthernBelle]

I ride a 22 on the front, 23 on the back. I think they have the same tube. The front seems to lose faster though. And by a fair amount.

[ehirsch83]

I check my air about every 2 rides, so every other day usually. I am usually down about 20psi. From 120-100.

Mr.Silver, what is the recommended psi for your tires? 100 seems low for a road bike...

[Grog]

Some tubes do let more air go than others. My front and back tires have different tubes that behave differently. One of them is a Schwalbe tube with extra-long stem (easy to recognize), I should take note to see if it's the one that looses more air... Next time I pump my tires I'll let you know.