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Measuring PSI - how exact are you?

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Measuring PSI - how exact are you?

Old 03-27-07, 11:31 AM
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ryanspeer
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Measuring PSI - how exact are you?

I read a lot of posts with people specifically stating how they'll ride at 125psi rear, 117 front, etc., but I wonder just how prevalent it is to be SOOOO specific. I personally have never owned anything other than a standard shrader valve tool for car tires, which we all know isn't exactly the most precise instrument in the world. That being said, I've always based my tires off of how they feel manually to me when I squeeze/push on them.

How specific are you all REALLY with this? I mean, honestly - all BS aside.

Just curious.
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Old 03-27-07, 11:35 AM
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OCPness in effect there. Realistically sidewall casing has a bigger effect on ride than 3 or 4 PSI.
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Old 03-27-07, 11:36 AM
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I always pump mine up between 120 and 125. As long as it's in that area I'm happy.
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Old 03-27-07, 11:38 AM
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i would put a higher psi in the back because thats where most of your weight is and a little less in the front so its a little smoother
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Old 03-27-07, 11:49 AM
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Its not to hard to line up the needle with the desired psi. Whether gauge is calibrated is a different story.

Also I'd expect a slight variation in psi during ride. I pump in in AM at 70F, end of ride its 100F and tires been rolling on hot pavement.

In winter (30-55F) I check pressure every week or so and it goes down 2-3psi at most. In summer (90-120F) it goes down this much or more in 2 days. Rubber is more permeable as temp goes up.

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Old 03-27-07, 12:11 PM
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If it's anywhere in the neighborhood of 120 +/-5, I'm happy with it. I really can't tell the difference with a few psi.
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Old 03-27-07, 12:12 PM
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As accurate as my thumb, and my butt allow.

Even if you're using a precisely calibrated guage, it's not measuring the pressure, after you've lost a little removing it.

So why sweat 5lbs plus or minus?
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Old 03-27-07, 12:14 PM
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When they pass my thumb pressure test, they've got enough air.
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Old 03-27-07, 12:16 PM
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Pressing hard with your thumb, tire should give up just a little bit.
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Old 03-27-07, 12:17 PM
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not accurate here. as long as it's in range, it's all good.
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Old 03-27-07, 12:32 PM
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Originally Posted by ryanspeer
I read a lot of posts with people specifically stating how they'll ride at 125psi rear, 117 front, etc., but I wonder just how prevalent it is to be SOOOO specific. I personally have never owned anything other than a standard shrader valve tool for car tires, which we all know isn't exactly the most precise instrument in the world. That being said, I've always based my tires off of how they feel manually to me when I squeeze/push on them.

How specific are you all REALLY with this? I mean, honestly - all BS aside.

Just curious.
9/10 times I use my Zefal hand pump and have no idea what psi I'm riding at. Yes, it's really that unimportant. As long as you've got enough to protect the rim, you're fine.
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Old 03-27-07, 12:40 PM
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I try to pump before each ride(my upperbody workout). I usually fill to about 120; however, when I pull the pump head off I'm not sure how much psi I am actually losing.
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Old 03-27-07, 12:53 PM
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Originally Posted by crash13
I try to pump before each ride(my upperbody workout). I usually fill to about 120; however, when I pull the pump head off I'm not sure how much psi I am actually losing.
Most of the air you are hearing / losing is actually coming out of the pump, not your tire.
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Old 03-27-07, 02:26 PM
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Itry to be as exact as most gauges: <5 PSI.
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