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newbie tire pressure ?(7 posts)

newbie tire pressure ?rweddy1
Aug 29, 2003 12:37 PM
I have 700 x 23 road tires and was wondering what pressure I should run them at?

Richard Eddy
Castle Rock CO
10+ Mountian, 1 month road
re: newbie tire pressure ?gtscottie
Aug 29, 2003 1:00 PM
probably around 110 or 120 psi but just check on the side of the tire and use what they recommend. I run 110 in mine.
Whatever it says on the side of the tire -- once you figure outbill
Aug 29, 2003 1:02 PM
the range, you have to decide what you like, which depends on your weight, your tolerance for getting bounced around versus desire to be cushioned, the local road surfaces, etc. Usually, though, about 110 is a good tweener PSI that most all tires can handle, which likely will give a firm enough ride without jarring your fillings loose.
Road tires vary in recommended pressures from about 90-110 as a minimum recommended to as high as about 145 for a maximum (which is as high for clinchers I think that I have ever seen), with a lot of tires in the 110-115 range for a recommended maximum psi. Tubulars typically can be pumped up higher/harder -- I think some you can take as high as 170.
The number on the tire is the maximum rating.MikeBiker
Aug 29, 2003 5:42 PM
It depends somewhat on your weight as to what you should be running in the tire. I am 177lbs and run 95 PSI in my 23s. I used to run 110 PSI but had much more flats at the high pressure.

Mike
Uncle Al says 85 to 90 psigContinental
Aug 30, 2003 5:15 AM
Try the lower pressure recommended by Uncle Al. You'll like the difference. Here is a great link for cycling info http://www.roadbikerider.com/ Here's his advice on tire pressure:

DEAR UNCLE AL: Perhaps you can settle an argument at our bike club. I like riding 20-mm-wide tires inflated to 120-130 pounds. I feel faster because of what I think is lower rolling resistance. Others argue for a 23C width at 100-110 psi, saying these tires are more efficient because they absorb pavement irregularities better. I weigh 175 pounds and ride at an average of 18+ mph on a variety of road surfaces. So who's right about width and pressure? -- Greg C.

UNCLE AL FIRES BACK: Soften up, Greg!

Most everyone I know runs too much pressure. Welcome to the club. Over many years of testing and talking to guys who live on their bikes, I'm convinced there is little reason to run more than 95-100 psi -- and there are compelling reasons to run 85-90 psi.

High pressure, say 100-120 psi, guarantees short tire life, poor cornering and lots of punctures. A rock-solid tire cuts/punctures more easily than it would at a lower pressure. Also, a softer tire can "smear" -- conform better to objects encountered on the road. Why make the ride even rougher on America's ever-crumbling road surfaces?

Admittedly, I weigh 210 pounds and ride on really poor road surfaces. These things influence my opinions. I run 85-90 psi front and 90-95 psi rear on 700x23C clincher tires. I do not have flats! Plus, bumps are less of an issue, and my bike corners as if on rails on high-speed descents. I get 1,000-1,500 miles out of a rear tire. When I ran much higher pressure many years ago, I got no more than 500 miles.

So, my advice is never to run smaller than 23C. Use good tubes, air them up before every ride and spend extra for premium tires -- they'll pay you back in extra mileage and better handling.

One more thing: Don't buy a race-specific tire to train on. If it's advertised to last only 500 miles, they aren't lying. Shaving grams off of training tires is silly and wasteful, and you won't get the low-weight advantage when event time comes if you ride the light stuff all the time. Make gram shaving your secret weapon, if only in your mind, when it counts.

Do as I recommend and I promise fewer flats, happier miles and no noticeable increase in rolling resistance (the great myth). Plus, you'll waste fewer resources, both financial and natural.
full of crapola....merckx56
Aug 30, 2003 7:20 AM
try diving a 23 tire into a corner at 30mph with 85 pounds in it. You'll be on the ground wondering what the hell happened!! Or stand up on a climb in the big ring and really jam on it...you'll sit right back down, I guarantee!
Rider weight does play an important role. A heavy rider (180) at 120 psi will deflect a tire more than a 150 pound rider, thus causing more contact with the road surface, consequently increasing rolling resistance. If I, at 175lbs, tried to ride a tire at 85-90 pounds, it would feel flat and probably pinch flat over RR tracks. I rode home tuesday night with about 80 in my rear tire (slow leak) and it felt absolutely flat! If you ride enough, and truly understand how you bike handles, you will be able to detect small changes in pressure, be it front or rear.
If 85 pounds was the optimum pressure, pros would be riding it. I've personally seen many, many pros air up to 110-120 before rides.
Type of tire is equally as important. A crappy wire bead tire with heavy tread and sidewalls can be ridden at lower pressures, so can bigger tires. Put 90 pounds in a Conti Supersonic and try it out. It'll ride like a flat!
re: newbie tire pressure ?tube_ee
Aug 30, 2003 8:29 PM
Here's the deal. The number on the sidewall is the maximum safe working pressure. It is obtained by mounting the tire on a standard test rim, and filling it with air until it blows off the rim or explodes. That pressure is divided by a government-mandated constant, and the resulting number is printed on the tire.

Uncle Al is right. Despite what a previous poster said. In the real world, a lower-pressure tire will corner better in most situations. A 180 lb rider on a 20 lb bike with 110 psi tires gives contact patches of 1.09 sq. in. rear and .73 sq. in. front, assuming 60/40 frnnt/rear wieght distribution.

Reducing pressure to 90 psi yields contact patches of 1.33 and .89 sq. in. front and rear. SInce traction is a function of the amount of rubber in contact with the road, lower pressure = more grip. Also, on rougher surfaces, the lower pressure tire will deform more, and therefore is less likely to skip. Again, better cornering.

The only valid reason to run high pressure is for rolling resistance. I don't have the formulas handy, but my suspicion is that the differences in rider fatigue and comfort would be much more significant over the course of a long ride or race than any difference in rolling resistance.

Peace and Grease,
--Shannon "counter-intuitive" Menkveld