B1KE

Hey everyone,

Great forum! I'm new to road biking and recently got my bike tuned up. It's getting cold here in Canada and the shop I was at pumped my tires down to 80 psi (I have 30mm tires with a suggests psi of 85-95). They said it's better to run lower pressure in the winter but I'm thinking the psi is too low and with such a low psi I'm more prone to getting a puncture. What is the correct PSI to run in the winter?

Bunyanderman

Run what feels comfortable, 80 psi will give you more slightly more cornering grip, better wet traction, better dirt traction etc, but you have more rolling resistance. 30mm tires should be fine at 80, if you are over 180 pounds you could bump it to 90.

B1KE

I'm right at 180lb, good to know that 80 isn't too soft I think I'll leave it at that or bump it up to 90 if I see a big difference.

gaucho777 

+1. Traction is key in poor weather. As a native Californian, never took cold into too much consideration, but it's conceivable Canada-style cold weather could reduce the softness of the rubber and therefore reduce traction. Mostly it's the wetness/ice. Something to look out for is pinch flats. (Are you familiar with this term? Usually caused by an impact such as a pothole on too low of pressure, resulting in the tube getting "pinched" between the rim edge and the road/hazard. Leaves a tell-tale mark of two parallel holes in the tube, like a snakebite.) If you end up with pinch flats, then increase the pressure a little.

B1KE

Haven't been looking but thanks for telling me, will be on the look out now.

rpenmanparker 

The problem is that if you pump the tires at normal room temperature indoors, then go for a ride near freezing, you will lose about 10% of the pressure due to the tenperature drop. So if 80 is what you want to ride at, you'd better leave it at 90 when pumping. You did say Canada, eh?

But if you are riding on clear, dry pavement, I can't see any reason to want lower pressure in the winter. That would suggest that the initial inflation should actually be HIGHER not lower to account for the drop at lower temperature. If the bike is stored and pumped up in an unheated space, however, what you pump will be closer to what you get. Especially when just topping tires off. The pumping work does raise the air temperature in the tire, but when topping off that increase should be negligible.

Marcus_Ti

Not 10%. Rule of thumb is that for every 10F you lose in temp the pressure goes down 1 PSI.. To lose 10PSI means a delta of 80F from inside to outside. Which for me would mean that with my house at 65F in winter, it would have to be -15F outside.

rpenmanparker 

Thanks. I was just coming back to change it. You are correct that I was wrong, but not by quite so much as you think. I was figuring a difference between 70F and 40F. That's a difference of 30F or 17K. 17 over 294 is about 6% or 5-6 psi. I don't know about rules of thumb. But it is pretty easy to figure out rigorously. If you don't screw up at first. The rule should actually be about 1.6 psi per 10 degree F for road bikes at ambient temperatures. The rule you are using would apply better to lower pressure wider tires. That's why it isn't such a great rule. The relationship is relative to the original tire pressure, not absolute.

Igualmente

eh?

rpenmanparker 

Sh*t. Per 10 deg F. Too early in the morning. Fixed.

mercator

Welcome to the forum (ya hoser)
A lot of the people on here have a distinctly non-canadian idea of what winter is like. In my winter riding, I see lots of ice and snow, with stretches of bare pavement when the weather relents and the roads get cleared.

Because of the variability in conditions, I adjust my tire pressure to suit, going down to about 50psi for ice and snow. This is with 32mm tires, rated for max inflation of 80psi. If I don't know what the roads are like before I head out, I pump up to the max and then stop to let some pressure out if needed.

I also use different tires for different conditions, including studded tires. In all of these considerations, experience is the key and you will need to find out what works for you.

noglider 

A pressure too low will Make you vulnerable to flats, but I think you would have to go to 40 or less to get that vulnerability. I recently rode at 30 with 32mm tires, as an experiment. My tires didn't bottom out. I don't recommend this, but I offer it as a datum.

Jiggle

I'm 155lbs with 30mm/29mm tires front/rear. I inflate them to 65/55psi year round. No problems and they ride very nicely.

fietsbob

Winter where? Canada ? You mean the trainer stand or the Rollers?