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Old 05-08-07, 10:12 AM   #1
Stallionforce
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Tire pressure for TT

What do you guys run? I have a Hed/Hed Tri combo, clincher. I've been running 110 but thought perhaps I could go higher. I know at a certain point the tire sort of 'bounces' on the texture of the pavement.
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Old 05-08-07, 10:16 AM   #2
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id say go as high as the tires will allow for the lowest rolling resistance, but im not a TT pro.
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Old 05-08-07, 10:17 AM   #3
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running a 19mm conti olympic tire up front @ 130psi and a rear Tufo elite in the rear @ 160. Front is a little bonuncy but managable. Rear feels perfect aspecially when you want to sprint on it.
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Old 05-08-07, 10:20 AM   #4
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it will depend on you tire also, a pro 2 race is 110psi max but tufo go much higher. 110 is fine and you wont need to go higher on a clincher.
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Old 05-08-07, 10:24 AM   #5
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Just a point that, '110' is just a suggestion. I've ridden 140 in tires that say max 110, the ride sucks on the road @ 140 but nothing exploded/
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Old 05-08-07, 10:45 AM   #6
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Above a certain point the rolling resistance actually increases with tire pressure due to the wasted energy in bouncing. Someone has previously posted a nice article with lots of fancy graphs to this effect, but I'm not about to go find it.
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Old 05-08-07, 10:48 AM   #7
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Live on the edge dude. 160lbs.
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Old 05-08-07, 10:49 AM   #8
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I've run at 150 psi on vredsteins. it'll all depend on type of tire, wheel and their max. you don't want a tire blowing off a rim.
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Old 05-08-07, 11:00 AM   #9
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Quote:
Originally Posted by VosBike
Above a certain point the rolling resistance actually increases with tire pressure due to the wasted energy in bouncing. Someone has previously posted a nice article with lots of fancy graphs to this effect, but I'm not about to go find it.
I can't find the article, but the number I remember is 120psi. I'd say there would have to be a very good reason and some quality supporting data to go higher. Unless the race is on a smooth wood track, 140 psi would definitely be slower than 120.
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Old 05-08-07, 11:07 AM   #10
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Tire pressure/ Rolling resitence should be a sticky thread. So we don't have to keep pulling up the data and links that establish the point Asgelle makes.

http://www.velonews.com/tech/report/...es/7508.0.html

http://www.velonews.com/tech/report/...es/7507.0.html

According to the Tech guy at Zipp:

The other issue to consider is that most every tire on the market runs at optimal rolling resistance between 105 and 125psi depending on load and road surface condition. We have seen data from numerous manufacturers and had enlightening talks with others to learn that nylon cased tires like Michelin or Continental tend to run optimally around 105-115 and cotton or bias cased tires like Vittoria or Vredestein tend to run optimally at 115-125 maybe as high as 130 for Vredestein, but all of them actually will increase in rr at higher pressures due to the tread rubber beginning to fail in shear as it locally deforms to meet the contour of the road imperfections when the casing is too rigid. Think of it in terms of heat input, as the overinflated tire struggles to conform to all the tiny surface imperfections to make the necessary contact patch, a lot of heat is generated. Not only is there higher rr, but faster tire wear as well at higher pressures, not to mention the tires decreasing ability to stay mounted on the rim as pressure increases. In an ideal world tire manufacturers would list a recommended pressure and not just a MAX pressure (the max pressure is simply a predetermined percentage of the bursting pressure of a given tire as set out by industry standards and has nothing to do with the pressure you should actually run) but they are between the rock and hard place as consumers continually push for higher and higher pressures feeling that ‘if some is good, more is better'. Of course none of this even mentions comfort, which we believe to be of increasing importance as more and more data has shown fatigue to be caused by vibration. It may be that by increasing tire pressure by 20-25 psi, you feel faster as your tires are transfering more of the high frequency vibration to your body (you're feeling a higher frequency 'faster' vibrations' so it really does 'feel' faster) but are actually expending more energy to do it, while simultaneously wearing out the tires faster and inducing fatigue.

Looking to pro road teams, most of them are running 100-110 psi in tubulars and 105-120 psi in clinchers, and this has been a bit of a knock against the clinchers from the pros, that they prefer the lower pressures for improved handling, grip and feel, but need additional air to prevent pinch flats. Especially of issue are rainy races, where they may even lower pressure to 95 psi or so for better grip and control in the corners. The only real exception here would be track racing, especially on wood, where the surface is so smooth that very high tire pressures can yield excellent RR results, but still generally reduce grip slightly, but even this is specific as a board track may runn well at 220psi, but a concrete track favors 150-160psi, and some track surfaces are no better than most roads...

Last edited by merlinextraligh; 05-08-07 at 11:13 AM.
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Old 05-08-07, 01:34 PM   #11
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Wow, especially thorough, thanks Merlin (and others). I have Deda Tre RS Corsa's, 23's. It seems 110 is not a bad pressure for clinchers, unless it's wet. I think I will continue to run 110.
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