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Is this site correct for tyre pressure?

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Is this site correct for tyre pressure?

Old 10-11-12, 04:31 AM
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Is this site correct for tyre pressure?

https://www.dorkypantsr.us/bike-tire-...alculator.html

I'm about 150 and bike is 16, so total weight of 166. That site gives me 76psi and 94psi for front/back. I usually ride with 100/110. I fill till that once a week, an it slowly gets less I suppose, but 75/95 looks very low doesn't it?
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Old 10-11-12, 05:05 AM
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I'd say the calculations are bad. It tells me to run 147 lbs in the rear...uh no.
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Old 10-11-12, 06:20 AM
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Stick with 100/110. Most of those calculators are set up for touring bikes loaded with gear, wide tires, and going slow.
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Old 10-11-12, 06:39 AM
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Originally Posted by deepakvrao
https://www.dorkypantsr.us/bike-tire-...alculator.html

I'm about 150 and bike is 16, so total weight of 166. That site gives me 76psi and 94psi for front/back. I usually ride with 100/110. I fill till that once a week, an it slowly gets less I suppose, but 75/95 looks very low doesn't it?
I use it for my wife and I for everything from light road cycling to touring and it works great. Wife is 105# and I'm 165 to 180 depending on the season. Bikes weigh from 16# to 70# (loaded touring). I've had no pinch flats since using it and I ride through some pretty nasty roads. For me, I was able to lower the front but needed to increase the rear a bit on my road bike. It made the ride more comfortable and have eliminated pinch flats for me (wife never had any because she is light and was over inflated.

Be sure to include the weight of your clothes, water and toolkit. Those can add up to 8#. Also, weigh your bike, don't trust published weights.

FWIW, if you now fill only once a week starting at 100/110, you're probably below 95 rear by the time that you refill. If you use the calculator, you should top off at least every other day with 23s until you get a feel of how much you lose between fills.

Last edited by rogerstg; 10-11-12 at 06:46 AM.
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Old 10-11-12, 06:42 AM
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Thats correct for tyres. Now if you want to air up tires...
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Old 10-11-12, 07:43 AM
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It does SOUND low, but I've tried it briefly and it seems to work fine. FWIW, my 64-cm Atlantis and I weigh probably 275 pounds, and I'm using 32mm Paselas.
I think what this is really whispering to a lot of us is, "Use wider tires..."
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Old 10-11-12, 07:54 AM
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I think the Michelin Tire Chart (the bottom calculation) is a much better starting point but all these calculators are just guides and not absolute truth.

I would say that if you are running 23mm tires, oops tyres, you could probably get away with 90F and 100R.

I would also say that lots of newbie enthusiast cyclists (and even old ones) tend to OVERinflate their tires, often to the "max" on the tire which is unwise IMO. I know lots of guys in my club who weigh 150 pounds do inflate their tires to 115+ which is probably too much.
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Old 10-11-12, 07:57 AM
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The calculator is right if you believe Jan Heine's premise that 15% tire deflection is optimum for rolling resistance and comfort. I have been using his formula for the last few yrs (hand calculations, didn't know there was an online option), and I have been happy.

Super high inflation pressures can really beat you up, and the higher frequency vibrations that come along with higher pressures may make you feel faster, but your really not! Of course thats only if you believe Jan Heine's premise.

Super high inflation pressures are still used for hardwood velodrome tracks, but are not beneficial for the road.

Last edited by Hairy Hands; 10-11-12 at 08:01 AM.
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Old 10-11-12, 08:00 AM
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111/170 it says. I run 95/105 in my michelin p3r's with no flats in 1000 miles over pretty ugly terrain.
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Old 10-11-12, 08:20 AM
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when I was 150 I liked 90/90. If I run the front less its usually by 10 psi max differential. The only reason to have extremely different prussures is if you have extremely different tyres.

I can't wait till spring when I get out my cx bike with 32c all city tires running at 80-90 psi.
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Old 10-11-12, 10:56 AM
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I use the Michelin tire pressure chart (also shown on the OP's link). Works great for me.
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