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How much do your tires deflect when you're riding? If I look down it looks like my rear tire is squishing quite a bit. I run a 25mm Specialized all condition at about 90-95 psi on my commuter and I weigh 195.
 

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not much, i run 23mm bonti's (soon to be pro2race's hopefully) at 120 psi (reccomended 120 psi max) but I race, and I weigh 125. I was running them at 110 this weekend in the rain to try to get some extra grip (lower psi = more deflection = more surface area = more grip possibly?) in a crit, and they still didn't deflect that much. They at least felt more grippy at the lower psi in a few test runs, so i guess thats all that matters.
 

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CC09 said:
not much, i run 23mm bonti's (soon to be pro2race's hopefully) at 120 psi (reccomended 120 psi max) but I race, and I weigh 125. I was running them at 110 this weekend in the rain to try to get some extra grip (lower psi = more deflection = more surface area = more grip possibly?) in a crit, and they still didn't deflect that much. They at least felt more grippy at the lower psi in a few test runs, so i guess thats all that matters.
You must enjoy the pounding from over-inflated tires. In the 23mm flavor, I run a max of 110 psi, but I'll run as low as 100 in 'em. At your weight, running your tires at max inflation pressure will not make you faster. In fact, it'll make you a bit slower as energy gets wasted when the tire hops over surface irregularities as opposed to deflecting to conform to irregurlarities. Running at max pressure you'll also get shorter tire life.
 

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FattyCBR said:
How much do your tires deflect when you're riding? If I look down it looks like my rear tire is squishing quite a bit. I run a 25mm Specialized all condition at about 90-95 psi on my commuter and I weigh 195.
The tire (especially on the rear) is most of your suspension. As long as you aren't getting pinch flats, it's all good.
 

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alienator said:
You must enjoy the pounding from over-inflated tires. In the 23mm flavor, I run a max of 110 psi, but I'll run as low as 100 in 'em. At your weight, running your tires at max inflation pressure will not make you faster. In fact, it'll make you a bit slower as energy gets wasted when the tire hops over surface irregularities as opposed to deflecting to conform to irregurlarities. Running at max pressure you'll also get shorter tire life.
Hmm. should i run them between 100 and 110 then? how much would it expand life?
 

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More tire in contact with the road...

CC09 said:
Hmm. should i run them between 100 and 110 then? how much would it expand life?
Lower pressures equal to more tire being in contact with the road and this distributes the power onto the road over a greater area of the tire. Hence, less pressure on any part of the tire and less wear results.

But hey, as a racer you might argue that more area in contact equates to more rolling resistance. This is true but the increase in minimal and the benefits might outweigh the increase in rolling resistance. Overinflated tires corner lousy, bounce on rough roads and is less comfortable. I am 150lbs and I used to race on 130-140psi until another experienced racer told me to go easy on the pressure. Now I run 105 front and 110 behind on race day. I go farther and faster because the road shakes and shatters me less with the reduced pressures. I can also corner better with the improved grip.

I guess at your weight, you can easily do a 95 front and 100 rear. No harm trying it out.
 

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Vinokourov said:
Lower pressures equal to more tire being in contact with the road and this distributes the power onto the road over a greater area of the tire. Hence, less pressure on any part of the tire and less wear results.

But hey, as a racer you might argue that more area in contact equates to more rolling resistance. This is true but the increase in minimal and the benefits might outweigh the increase in rolling resistance. Overinflated tires corner lousy, bounce on rough roads and is less comfortable. I am 150lbs and I used to race on 130-140psi until another experienced racer told me to go easy on the pressure. Now I run 105 front and 110 behind on race day. I go farther and faster because the road shakes and shatters me less with the reduced pressures. I can also corner better with the improved grip.

I guess at your weight, you can easily do a 95 front and 100 rear. No harm trying it out.
at what psi would I have to start really worrying about flats? 75, 85? I guess i'll try out 100 and go from there.
 
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