Tire PSI?
#26
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I'll be explicit. Let's say you go out for a ride in winter and it will be 0C all day, what pressure do you put in your tire. Now it''s summer, the temp is 30C (same tires, same combined weight of you and the bike as in winter), what pressure do you use now?
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very simple. The same presssure! Because the guage reads air pressue at ambient temperature.
whatever temperature it is, the guage reads the pressure at that temperature.
/markp
whatever temperature it is, the guage reads the pressure at that temperature.
/markp
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by about 5 psi, that's how so.
On hot summer days not only is it hot in the air like say 95 degrees, the blacktop can be around 140 degrees on a windless day with direct overhead sun. So tires can get quite hot, and when that happens up goes the psi from the heat. If you have a modern car with tire pressure read out from all 4 tires, you can see that when setting in the garage the tire heat is pretty low, but take out onto the highway and those readings slowly go up, your bike tires are doing the same thing just not as much because you're not doing 80 mph.
On hot summer days not only is it hot in the air like say 95 degrees, the blacktop can be around 140 degrees on a windless day with direct overhead sun. So tires can get quite hot, and when that happens up goes the psi from the heat. If you have a modern car with tire pressure read out from all 4 tires, you can see that when setting in the garage the tire heat is pretty low, but take out onto the highway and those readings slowly go up, your bike tires are doing the same thing just not as much because you're not doing 80 mph.
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There's one scenario where you might keep temperature in mind. If you pump up the tires in an indoor environmentally controlled room, then take the bike out into very hot or cold weather, it could be a factor. Air conditioners and heaters are real things. Obviously, if you fill your tires with 72 degree air, and then ride in 90 degree heat, there will be some pressure increase. Don't know how noticeable it might be, but if you're one of those super high pressure guys, use outdoor air.
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#32
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But for a typical 28mm tire on a common road bike, ridden in non competitive conditions, 80-90 psi is a good starting point.
I'm sceptical that a calculator or app can better determine the right tire pressure than I can do for myself. Remember air temperature has something to do with it too.
/markp
I'm sceptical that a calculator or app can better determine the right tire pressure than I can do for myself. Remember air temperature has something to do with it too.
/markp
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Billydog Many of us check the tire pressure and pump them up to our chosen PSI almost every time we go for a ride.
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And yes, I do pump them up every time I check them. I use the gauge on the pump, so since it's already connected. I'll give the pump a stroke or two to top off the tire.
Don't know if the gauge is accurate, but it is consistent. And the graduation marks are sufficient and large enough so that I can easily inflate them to within a precision of .5 psi.
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Only 1/2 psi a day? Are we talking about thin 700x 20 to 28c sized tubes? I use on average 100 gram tubes and for the last 40 years or so I average about a pound to two pounds a day depending on the thickness of the tube and the manufacture, maybe heavier 130 plus gram tubes would lose 1/2 psi a day, I know my touring bike that uses a 35 to 45c tube loses about a pound a week, not sure what the weight of those are. Of course latex tubes lose a lot more at around 30 psi a day if I remember correctly.
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I realized I was putting too much thought into this when I measured what I considered good enough to finish a ride after a roadside flat, and it was a full 40 psi lower than I typically ride at. Basically, it really doesn't feel much different. In that context, obsessing about 5 pounds margins either way seems a bit silly.
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I realized I was putting too much thought into this when I measured what I considered good enough to finish a ride after a roadside flat, and it was a full 40 psi lower than I typically ride at. Basically, it really doesn't feel much different. In that context, obsessing about 5 pounds margins either way seems a bit silly.
1. Tubeless works, since I obviously punctured and didn't even realize it.
2. I should probably be running lower psi.
3. Obsessing over tiny differences is pretty silly.
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I'm full of PSi!
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I've always preferred my tires to be at a slightly lower pressure. Much better more comfortable ride and better traction. I have never inflated my tires to the max PSI that is on the tire sidewall.
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