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Tire Pressure

Old 06-07-22, 05:22 PM
  #26  
PeteHski
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Originally Posted by rclouviere
I’ve always run at least 110psi. “Feels” faster to and how it’s always been for me. Lower psi just seems slower. I know there’s been lots of testing on this, but I’m just not sure now. The silica chart indicates i should be around 95psi
Why not believe the more objective testing? The Silca calculator is probably a good starting point. If you play around with their online calculator you will note that it recommends lower pressures on worn or crappy roads. 110 psi is almost certainly too high.
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Old 06-07-22, 05:40 PM
  #27  
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Originally Posted by WhyFi
Ew, David.
Like riding on knife edges! I can feet every molecule of the pavement. “Tactile feedback” sums it up nicely.
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Old 06-07-22, 05:44 PM
  #28  
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Originally Posted by smd4
Like riding on knife edges! I can feet every molecule of the pavement. “Tactile feedback” sums it up nicely.
"Doing it wrong" sums it up better. Well, if you're interested in performance, at least.
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Old 06-07-22, 05:45 PM
  #29  
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Originally Posted by rclouviere
I’ve always run at least 110psi. “Feels” faster to and how it’s always been for me. Lower psi just seems slower. I know there’s been lots of testing on this, but I’m just not sure now. The silica chart indicates i should be around 95psi
Listen to this sometime - https://cyclingtips.com/2016/08/cycl...and-pressures/
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Old 06-07-22, 05:54 PM
  #30  
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Originally Posted by WhyFi
"Doing it wrong" sums it up better. Well, if you're interested in performance, at least.
Pretty sure my RR is less than a 700 x 38 running at 80 psi or whatever wheelbarrow tires are inflated to today.

All this talk of “run what works for you” is a whole lot of horse feathers if you don’t do what everyone else does.

Now if you’ll excuse me—I have to go buy a carbon fiber disc brake bike while it’s still light out.
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Old 06-07-22, 05:58 PM
  #31  
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Originally Posted by smd4
Pretty sure my RR is less than a 700 x 38 running at 80 psi or whatever wheelbarrow tires are inflated to today.

All this talk of “run what works for you” is a whole lot of horse feathers if you don’t do what everyone else does.

Now if you’ll excuse me—I have to go buy a carbon fiber disc brake bike while it’s still light out.
If absurdly high pressure is what you prefer - you do you. If you think that it's faster - you're objectively wrong.
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Old 06-07-22, 06:02 PM
  #32  
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Originally Posted by WhyFi
If absurdly high pressure is what you prefer - you do you. If you think that it's faster - you're objectively wrong.
Never said I was a racer. Tires at that pressure are plenty fast. And responsive. And less cushy.
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Old 06-07-22, 06:15 PM
  #33  
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Originally Posted by smd4
Never said I was a racer.
Which is why I qualified my "doing it wrong" with, "if you're interested in performance."

Originally Posted by smd4
Tires at that pressure are plenty fast. And responsive. And less cushy.
Don't confuse your perception with reality. They're slower, they have a smaller contact patch, and being "less cushy" is the conversion of forward momentum in to upwards momentum.

There's a wide range of optimal, depending upon the rider, the tires, the surface, etc, but 140psi on pavement is well outside of the feasibly optimal range.
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Old 06-07-22, 06:29 PM
  #34  
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How is it “absurdly high” if that’s 5 psi below the high of the recommended range?
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Old 06-07-22, 06:34 PM
  #35  
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Originally Posted by smd4
How is it “absurdly high” if that’s 5 psi below the high of the recommended range?
Where are you getting a recommended range that shows 145psi on 23mm tires for you on pavement?
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Old 06-07-22, 06:35 PM
  #36  
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You do realize “smaller contact patch” = less friction = less rolling resistance?
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Old 06-07-22, 06:50 PM
  #37  
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Originally Posted by smd4
You do realize “smaller contact patch” = less friction = less rolling resistance?
So, if we want the fastest tires, we should be aiming for the least amount of friction between the road and the tire? Cool.
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Old 06-07-22, 06:58 PM
  #38  
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I just look at the sidewall of the tire and see what the manufacturer has imprinted on it. Currently running 700x32 tires and I pump them up to the recommended 80 psi max. I used to run 700x28 that had a max rating of 110 psi.
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Old 06-07-22, 07:25 PM
  #39  
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Originally Posted by WhyFi
"Doing it wrong" sums it up better. Well, if you're interested in performance, at least.
^This^

Originally Posted by WhyFi
If absurdly high pressure is what you prefer - you do you. If you think that it's faster - you're objectively wrong.
And ^this^
Originally Posted by smd4
Never said I was a racer. Tires at that pressure are plenty fast. And responsive. And less cushy.
You're confused.
Originally Posted by smd4
You do realize “smaller contact patch” = less friction = less rolling resistance?
More confused.

Originally Posted by skidder
I just look at the sidewall of the tire and see what the manufacturer has imprinted on it. Currently running 700x32 tires and I pump them up to the recommended 80 psi max. I used to run 700x28 that had a max rating of 110 psi.
How much do you weigh? Do you think tire pressure might be related in some way to rider weight? Would you pump the tires of a 100lb rider to the same pressure as those of a 250lb rider? You just blindly went for the max pressure because...? 28mm tires at 110psi? You are genuinely confused.

You guys that think high pressure is fast because 'it feels fast' just don't get it. What you're feeling is the very definition of rolling resistance. If you're feeling every little bump and bit of texture it's because the bike AND you are going up and down. Not as efficient as if the bike AND you weren't going up and down. 'Feels' count for very little here, we're dealing with physics. Which are known as the LAWS of physics.
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Old 06-07-22, 08:04 PM
  #40  
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In Newton's pendulum, the kinetic energy of the first ball is transmitted through all the balls to the last because they are perfectly elastic and very hard. If the balls were perfectly inelastic, the last ball would not move at all because all of the balls would have absorbed all the energy.

In a hard tire, all the energy is transmitted through and you can feel all the vertical bumps. Not only do you go up and down, you go forward.

In a soft tire, the rubber absorbs all the energy and reduces your forward motion. Try riding on grass and sand where the soft ground is absorbing all the energy. Then compare that with riding on concrete, asphalt or on a perfectly smooth and hard track of a velodrome. The hard surface transmits all your energy.
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Old 06-07-22, 08:20 PM
  #41  
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Originally Posted by Daniel4
In a soft tire, the rubber absorbs all the energy and reduces your forward motion. Try riding on grass and sand where the soft ground is absorbing all the energy. Then compare that with riding on concrete, asphalt or on a perfectly smooth and hard track of a velodrome. The hard surface transmits all your energy.
So much wrong. Here, this might help. https://www.amazon.com/Bicycling-Sci...s%2C113&sr=1-1
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Old 06-07-22, 08:30 PM
  #42  
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Originally Posted by Daniel4
In Newton's pendulum, the kinetic energy of the first ball is transmitted through all the balls to the last because they are perfectly elastic and very hard. If the balls were perfectly inelastic, the last ball would not move at all because all of the balls would have absorbed all the energy.
Not sure it relates to tires, but this is not the way inelastic collisions work. Even if the balls collide inelasticly, momentum is conserved. So, after the collision, all the balls move together at the same, slower velocity dictated by the ratio of the mass of the first ball to the total mass of all the balls (times the initial velocity).

Stick blobs of clay at all the contact points and try it for yourself.

Otto

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Old 06-07-22, 08:45 PM
  #43  
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Originally Posted by cxwrench
Larry...just stop it. They're not the suggestions of physics, or the feels of physics, they're the LAWS of physics.
Bro ride your own ride... I work with physicists all day (im at a national laboratory in group looking for dark matter), there are too many variables to math out the fastest tires. The only reliable test is one done in real world conditions. Some people enjoy thin hard tires.
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Old 06-07-22, 08:46 PM
  #44  
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Originally Posted by LarrySellerz
there are too many variables to math out the fastest tires.
Actually no, https://www.recumbents.com/wisil/Mart...%20cycling.pdf
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Old 06-07-22, 08:47 PM
  #45  
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Originally Posted by WhyFi
Smooth is fast. Fast is smooth.
This is true but its almost entirely about technique not gear. This phrase was common when people were attempting to ride tires thinner than 20mm.
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Old 06-07-22, 08:48 PM
  #46  
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Originally Posted by asgelle
that link doesn't work, but yeah there are too many variables to math it out reliably
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Old 06-07-22, 08:49 PM
  #47  
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Originally Posted by skidder
I just look at the sidewall of the tire and see what the manufacturer has imprinted on it. Currently running 700x32 tires and I pump them up to the recommended 80 psi max. I used to run 700x28 that had a max rating of 110 psi.
You are mistaking the max inflation pressure for the recommended inflation pressure for whatever load the tires are carrying.
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Old 06-07-22, 08:51 PM
  #48  
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Originally Posted by LarrySellerz
Bro ride your own ride... I work with physicists all day (im at a national laboratory in group looking for dark matter), there are too many variables to math out the fastest tires. The only reliable test is one done in real world conditions. Some people enjoy thin hard tires.
Sweeping the floor and bringing them coffee doesn't qualify you as a physicist, Larry.
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Old 06-07-22, 08:51 PM
  #49  
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Originally Posted by LarrySellerz
that link doesn't work, but yeah there are too many variables to math it out reliably
Then try this https://www.researchgate.net/publica..._Cycling_Power
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Old 06-07-22, 08:52 PM
  #50  
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Originally Posted by smd4
You do realize “smaller contact patch” = less friction = less rolling resistance?
Sometimes when everyone is saying you're wrong, it's because you are wrong.
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