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Tire & Temperature ..
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This morning the tire pressure was (felt) just perfect .. 4.8bar in a Conti4KSII 23mm on a HED Black at 3°C temperature FW and 5.7bar RW for ≈ 95kg system weight (winter mountain of clothes) .. 10 hours later at 17°C the same set up on the same roads (opposite direction) was (felt) like a "iron-clad wood wheel" .. is there a rule of thumb to adjust tire pressure to ∆ temperature ?? Remembering some experiences 0.1bar for ∆ 6°C would come close ..

___/\___/\___/\___ the surfboard of the Kurpfalz is the road bike .. oSo >> Older, and faster ..
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Re: Tire & Temperature .. [sausskross] [ In reply to ]
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Did you have a way to measure the air pressure after it warmed up? What was it?

Did taking air out of the tires take care of the problem?

Indoor Triathlete - I thought I was right, until I realized I was wrong.
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Re: Tire & Temperature .. [IT] [ In reply to ]
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The pump showed the pressure before the morning ride .. to measure without some backpreassure the pump is not really good .. the pfft-pfft-pfft trick helped to "take care" .. other things that changed were the thinness of the bib tight pads ..

___/\___/\___/\___ the surfboard of the Kurpfalz is the road bike .. oSo >> Older, and faster ..
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Re: Tire & Temperature .. [sausskross] [ In reply to ]
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sausskross wrote:
This morning the tire pressure was (felt) just perfect .. 4.8bar in a Conti4KSII 23mm on a HED Black at 3°C temperature FW and 5.7bar RW for ≈ 95kg system weight (winter mountain of clothes) .. 10 hours later at 17°C the same set up on the same roads (opposite direction) was (felt) like a "iron-clad wood wheel" .. is there a rule of thumb to adjust tire pressure to ∆ temperature ?? Remembering some experiences 0.1bar for ∆ 6°C would come close ..

Your high school chemistry class gave you a way to estimate it using the ideal gas law... PV=nRT

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Ed O'Malley
www.VeloVetta.com
VeloVetta is developing AERO cycling shoes with CFD and wind tunnel testing.
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Re: Tire & Temperature .. [RowToTri] [ In reply to ]
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We could vote out classes at that time .. chemistry was on my list .. (the teachers were the problem not the science) .. thanks for the ideal gas law .. calculating with computers is fun ..

___/\___/\___/\___ the surfboard of the Kurpfalz is the road bike .. oSo >> Older, and faster ..
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Re: Tire & Temperature .. [sausskross] [ In reply to ]
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you can assume (not 100% correct but close enough) that the volume for all intents and purposes was constant so you can simplify the ideal gas law to P1/T1= P2*/T2 remember that T= 273+degC so in this case the change in pressure went from 5.7 bar to 5.99 bar. However if your tried your pump you could see if the 6 bar pressure was real.
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Re: Tire & Temperature .. [s5100e] [ In reply to ]
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Ok .. I'll change my rule of thumb to 0.1bar for ∆ 5°C .. thinking about the differences my senses were more focused on the front wheel ..

___/\___/\___/\___ the surfboard of the Kurpfalz is the road bike .. oSo >> Older, and faster ..
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Re: Tire & Temperature .. [sausskross] [ In reply to ]
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If the road is chipseal you will find better grip with a cold tyre.
This because the rubber is point loaded and the stiffer rubber resists deformation better.
If you are on very smooth Tarmac, the reverse is generally true with better grip as temperature is a little higher.
Depending on exactly what road surface you are on, temperature change may work either way for your tyre, weight, cornering speed, surface and pressure combination.

Put 25mm tyres on, way less critical because of the extra grip available.
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Re: Tire & Temperature .. [lyrrad] [ In reply to ]
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Thanx for the ideas .. these tires actually measure 27mm on the wide rim .. my question was not about safety, it was about the amount of wanted and needed feedback from the street that changed with temperature ..

___/\___/\___/\___ the surfboard of the Kurpfalz is the road bike .. oSo >> Older, and faster ..
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