General Discussion Triathlon Talk » Tire Pressure Rss Feed  
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2006-03-27 7:21 AM

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Elite
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Subject: Tire Pressure

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Issue No. 233 - 02/23/06:  Ride With Us

ISSN 1536-4143

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2.  Uncle Al:  Inflation Revelation  o^o  o^o  o^o  o^o  o^o  o^o

Tire pressure is one of the most controversial and misunderstood elements of road riding.

Most roadies are under the mistaken impression that unless pressure is well over 100 pounds per square inch (psi) it's like they'll be dragging around a boat anchor. Tire manufacturers perpetuate this myth by stamping a Maximum Tire Pressure value on the sidewall. For road tires, this can range from 110 psi to an astronomical 170 psi.

Combine these pressures with the super-stiff, radial-spoked wheels many riders are now using, and the result is some serious self-abuse.

Based on 40 years of wrenching and my discussions with tire experts and pro riders, there's no compelling reason to run more than 95 psi for 95% of your riding. Our roads are deteriorating faster than politicians can spend our tax dollars, and really high pressure means a really harsh ride.

I could also mention poor cornering, short tire life, and the promise of many punctures.

The key here is to ride the tire size that matches your weight. Many roadies are running 700x23C no matter what they weigh. If you're over 180 lbs. (82 kilos), 25C is a better choice. For us "Clydesdales" over 205 lbs. (93 kilos), 28C is the smart size.

I'm talking fast recreational riding here, not racing or touring. Racers can go narrower and tourers should go wider.

If your tire size corresponds to your weight, you can run 90-95 psi and not risk pinch flats. I guarantee you will roll just as fast or faster than you think you do on higher pressures. You'll descend and corner faster (and safer). You'll suffer fewer punctures, and your tires will last as much as five times longer.

So if you're a max-pressure person, try lowering the psi and upping the size (if your weight says you should). Wean yourself off high pressure bit by bit if you wish till you?re down to 90 psi front and 95 rear.

Then experience the suppleness your tires are supposed to possess. Check out how much smoother cornering is, how much more comfortable you are, and how much less fatigue you feel at the end of your rides. I bet you'll be pleasantly surprised.

-----------------------------------------------------------------------------------------------------------------

Thought this would be interesting to post and see the responses.

 



Edited by parrj 2006-03-27 7:22 AM


2006-03-27 7:29 AM
in reply to: #380139

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Extreme Veteran
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Subject: RE: Tire Pressure
Some intersting stuff.  I actually read something similar on Slowtwitch a while back posted by a guy who works at Zipp and he was talking about their tires and associated pressure.  It wasn't actually as low as this gentleman suggests, but it was MUCH lower than most people are riding.
2006-03-27 7:46 AM
in reply to: #380139

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Giver
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Subject: RE: Tire Pressure
parrj - 2006-03-27 8:21 AM

Based on 40 years of wrenching and my discussions with tire experts and pro riders, there's no compelling reason to run more than 95 psi for 95% of your riding.

 

Discussions are fun and all, but where's the data?

 

2006-03-27 8:11 AM
in reply to: #380155

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Elite
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Subject: RE: Tire Pressure
run4yrlif - 2006-03-27 8:46 AM
parrj - 2006-03-27 8:21 AM

Discussions are fun and all, but where's the data

Ask roadbikerider.com.  Just an article I found.

2006-03-27 11:03 AM
in reply to: #380139

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Subject: RE: Tire Pressure
Just like high performance cars the tires and pressures you run on the bike can have a big impact.

You want cush go wide and low pressure. Yo u want performance on a road bike go thin and higher pressures. Won't be comfy (car or bike) but it will perform.
I am only concerned with training and racing.

From the article:
"I'm talking fast recreational riding here, not racing or touring."



Edited by Nob 2006-03-27 11:04 AM
2006-03-27 12:35 PM
in reply to: #380392

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Not a Coach
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Subject: RE: Tire Pressure

Nob - 2006-03-27 11:03 AM  You want cush go wide and low pressure. Yo u want performance on a road bike go thin and higher pressures. Won't be comfy (car or bike) but it will perform. I am only concerned with training and racing. From the article: "I'm talking fast recreational riding here, not racing or touring."

This is far more debatable than you make it out.  Narrower tires can actually result in higher rolling resistance according to some studies, especially on certain rim-types.  High pressures help on a track, but don't appear to work as well on roads.  I saw a quote from someone at Zipp who said that it is common to see pros in Europe riding 90-95psi in the rain and 100-110 when dry.  I've seen a range of 100-120 as a guesstimate for optimizing rolling resistance depending on rider weight and road conditions.

The quote from the article you mention is also referring to recommended tire width, not pressure.



2006-03-27 1:10 PM
in reply to: #380139

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Expert
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Subject: RE: Tire Pressure
OK, I'm interested enough to do some research. If I find anything I will post it here.
2006-03-27 4:09 PM
in reply to: #380482

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Subject: RE: Tire Pressure
This is far more debatable than you make it out.


If you want to debate the difference between 100/130 or 160# of air and 21 and 23s no question. Then we start talking rider weight, road surface/conditions and ride comfort all need to be taken into account.

To go fast you have to do some research for your weight and conditions you'll use them in and the tire.

Example? 185# rider. 2700x23c tires. One takes 125# and is actually 23.5 to 23.70 wide. The other 2700x23 tire is more like 22.25 o 22.5c in width and has a pressure limit of 120#.

From riding them I can tell you which tire is easier to pedal and which has a more comfortable but slower to ride.

Funny part is the retail price of the tires also matches the performance.

In this case the Pro2 is thinner, takes less pressure and is faster IMO than the other tire. Also retails for $10 more.YMMV or course.

My point is there is more to tire performance and it is a BIG factor on your ride and how you use the bike.
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