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Tire pressure

Old 12-03-23, 06:02 AM
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Play with the numbers in the tire pressure calculator - not every input is created equal. Tire width makes a giant difference. Many other things do not.

Also, for what its worth, I use a DeWalt battery-powered air compressor to pump up my bike. I can set a pressure and forget it while the pump does all the work. Because the pump has a screen and a light, I can even do this in the dark and without glasses. Handy piece of equipment.
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Old 12-03-23, 08:09 AM
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Originally Posted by terrymorse
Higher pressure will reduce rolling resistance on a smooth surface. On real roads, a lower pressure usually reduces rolling resistance, as it absorbs bumps (as well a giving a smoother ride).
Lower pressure will only reduce rolling resistance by absorbing bumps up to a point. If the tires are bouncing as you pedal, the pressure is far too low. Flexing of the sidewalls increases rolling resistance.

Additionally, rider input and technique factor into the equation. Everyone seems to want to ride a bike as if it is damned sofa…with their posterior planted firmly on the saddle and then wondering why the bike rides so “hard”. Riding a bike is more like riding a horse. You don’t plant yourself in the saddle unless you want a very uncomfortable ride. Legs and arms provide suspension on a rigid bike (and on a suspended bike) and they do so to a larger degree than a relatively tiny air filled bladder.
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Old 12-03-23, 08:29 AM
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Originally Posted by PeteHski
A great way to guarantee a harsh, slow ride on anything other than perfectly smooth tarmac.
Quantify “slow”. 50% slower? 75% “slower”? Or more like 1% slower? This article from Schwalbe would suggest the latter. They compare a 37mm tire to a 60 mm tire and there is about a 10 watt difference in rolling resistance. That translates into about 1 kph of speed change. And an argument can be made that the 60mm tire results in a higher loss of speed than that due to the increased air resistance as well as the increased power needs to roll the extra mass down the road.

It’s not black and white
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Old 12-03-23, 02:28 PM
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Originally Posted by cyccommute
Quantify “slow”. 50% slower? 75% “slower”? Or more like 1% slower? This article from Schwalbe would suggest the latter. They compare a 37mm tire to a 60 mm tire and there is about a 10 watt difference in rolling resistance. That translates into about 1 kph of speed change. And an argument can be made that the 60mm tire results in a higher loss of speed than that due to the increased air resistance as well as the increased power needs to roll the extra mass down the road.

It’s not black and white
You appear to have converted my simple comment about not running max sidewall pressure as a default into a tyre width comparison.

Of course the speed differences are marginal, but the ride quality isn’t.
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Old 12-03-23, 02:37 PM
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Originally Posted by 50PlusCycling
Increasing tire pressure never decreases rolling resistance, ever.
Hmmm. Well, I guess that settles that.

But higher pressures, besides making for a harsh ride, shrink the contact patch, decreasing traction, and increasing the chances of skidding or losing control. FWIW, I worked for some time the motorcycle division of the Pirelli tire company, and understand a little bit about the subject.
Hmmm. Well, I guess that settles that.

Originally Posted by cyccommute
Lower pressure will only reduce rolling resistance by absorbing bumps up to a point. If the tires are bouncing as you pedal, the pressure is far too low. Flexing of the sidewalls increases rolling resistance.
Hmmm.
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Old 12-03-23, 02:37 PM
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When it comes to tire pressures, I just go by feel, it has never failed me yet.
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Old 12-03-23, 02:54 PM
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Originally Posted by ScottCommutes
Play with the numbers in the tire pressure calculator - not every input is created equal. Tire width makes a giant difference. Many other things do not.

Also, for what its worth, I use a DeWalt battery-powered air compressor to pump up my bike. I can set a pressure and forget it while the pump does all the work. Because the pump has a screen and a light, I can even do this in the dark and without glasses. Handy piece of equipment.
I also use a Dewalt battery powered portable inflator - one of the best purchases I’ve made

use it for bike and car / truck tires

have a few bike floor pumps - including two Silca pumps - and now only use them to partially inflate a tube before install

also have a small compressor - but have not used it in some time (especially since my father borrowed it and still has it)
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Old 12-03-23, 03:27 PM
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Originally Posted by 50PlusCycling
Tire pressure is all about trial and error. Different tires and tires sizes react differently at different pressures. This is very easy to experiment with, as your tires will gradually deflate after you fill them up to the labeled pressure. In time you can find that sweet spot where you get a good combination of comfort and rolling resistance. When it feels right, check the tire pressure, and stick with that pressure.
But - and sometimes a rather important "but" - if that sweet spot takes your pressure down to where you might pinch flat going down one of your faster hills, the consequences after the crash from trying to ride on a bare rim or the tire coming off and jamming in the stays/fork can be large. In racing terms as spelled out by several mentors of mine - any gains must be balanced out with the loss of conditioning that happens after crash injuries that you cannot ride through. This applies also to pushing more pressure than the tire or rim can handle.

Something you can do. That tire, the Zaffiro, is a mediocre tire. Better tires can 1) handle (usually) more pressure and 2) roll far better at all pressures, including higher pressures. You could run a 28c Rubino at 100 front, 105 rear and you'd be pleased. Spend the money for the 28c Corsa G at that pressure or higher and come back from rides with a huge smile on your face. (And 120 psi in a Corsa G won't phase it at all. I never would because I don't want my teeth knocked out at that pressure on that big a tire (I'm light) but I would have zero worry about that tire blowing at that pressure as long as I trusted the bead/rim (hook?) interface and my mounting skills.)

(I'm saying this for clincher tires, not tubeless. That's a whole new game I have not played. And I have had so-called "very good" tires blow off rims after real care adjusting the beads to be even. I now stay away from Challenge clinchers and stick with Vittoria.)
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Old 12-03-23, 03:38 PM
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Originally Posted by 79pmooney
But - and sometimes a rather important "but" - if that sweet spot takes your pressure down to where you might pinch flat going down one of your faster hills, the consequences after the crash from trying to ride on a bare rim or the tire coming off and jamming in the stays/fork can be large. In racing terms as spelled out by several mentors of mine - any gains must be balanced out with the loss of conditioning that happens after crash injuries that you cannot ride through. This applies also to pushing more pressure than the tire or rim can handle.

Something you can do. That tire, the Zaffiro, is a mediocre tire. Better tires can 1) handle (usually) more pressure and 2) roll far better at all pressures, including higher pressures. You could run a 28c Rubino at 100 front, 105 rear and you'd be pleased. Spend the money for the 28c Corsa G at that pressure or higher and come back from rides with a huge smile on your face. (And 120 psi in a Corsa G won't phase it at all. I never would because I don't want my teeth knocked out at that pressure on that big a tire (I'm light) but I would have zero worry about that tire blowing at that pressure as long as I trusted the bead/rim (hook?) interface and my mounting skills.)

(I'm saying this for clincher tires, not tubeless. That's a whole new game I have not played. And I have had so-called "very good" tires blow off rims after real care adjusting the beads to be even. I now stay away from Challenge clinchers and stick with Vittoria.)
I will look into those tires. I have these because my lbs said they were decent but better than what I had.
For the riding I am doing right now mine are fine.
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Old 12-03-23, 04:45 PM
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I go for max pressure.
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Old 12-04-23, 12:14 AM
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Originally Posted by wolfchild
When it comes to tire pressures, I just go by feel, it has never failed me yet.
What would “failure” be in this scenario?
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Old 12-04-23, 01:48 AM
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Originally Posted by terrymorse
What would “failure” be in this scenario?
Failure = no one responds to his post.
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Old 12-04-23, 08:48 AM
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I stay with lowest range for city tour .. If tire is for 40-55bl , I'll stay with 40bl
Never fail ..
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Old 12-04-23, 12:06 PM
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Originally Posted by terrymorse
What would “failure” be in this scenario?
You're fishing for an argument. I am sure you know what I meant...Never failed is the same as saying.this has always worked for me.
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Old 12-04-23, 01:51 PM
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Originally Posted by wolfchild
You're fishing for an argument. I am sure you know what I meant...Never failed is the same as saying.this has always worked for me.
So I assume that pressure by feel has "always worked for [you]" means that you have a tolerance for different pressures.
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Old 12-04-23, 03:24 PM
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I aired my tires to 85psi front and 90psi rear. Honestly that’s where they were and I just left them alone. I didn’t really feel a difference from when I aired them higher a while ago.

I have come to the conclusion that for me I prefer to have air inside the tube. It rides much smoother and is a lot quieter. I’m going to keep it this way.
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Old 12-04-23, 04:25 PM
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Originally Posted by pepperbelly

I have come to the conclusion that for me I prefer to have air inside the tube.
???
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Old 12-04-23, 04:31 PM
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Originally Posted by terrymorse
So I assume that pressure by feel has "always worked for [you]" means that you have a tolerance for different pressures.
It depends on the terrain which I am riding. I will use much lower pressure for off road riding than for pavement.
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Old 12-07-23, 05:29 PM
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Originally Posted by wolfchild
When it comes to tire pressures, I just go by feel, it has never failed me yet.
This is the way
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Old 12-14-23, 08:38 AM
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whether it's right or no.....
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Old 12-14-23, 09:12 PM
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Originally Posted by Wildwood

whether it's right or no.....
Are you kidding? Maybe 95% of the folks on this board won’t have a clue what this is/means.
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Old 12-15-23, 12:04 AM
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Originally Posted by smd4
Are you kidding? Maybe 95% of the folks on this board won’t have a clue what this is/means.
Looks like a bantha skull but I don’t get the reference. .
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Old 12-15-23, 10:38 AM
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Tire Pressure?
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Old 12-15-23, 12:16 PM
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One thing that is not noted it that accuracy of the psi gauges on pumps vary wildly.

it is a good idea to get a quality pressure gauge to check what the actual is.

complete luxury but I use a Milwaukee batter powered inflator, added a silca chuck. make this it all super easy and accurate (checked with a good gauge)

I like the rene herse calculator https://www.renehersecycles.com/tire...culator-intro/
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Old 12-15-23, 03:23 PM
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Originally Posted by squirtdad
One thing that is not noted it that accuracy of the psi gauges on pumps vary wildly.

it is a good idea to get a quality pressure gauge to check what the actual is.

complete luxury but I use a Milwaukee batter powered inflator, added a silca chuck. make this it all super easy and accurate (checked with a good gauge)

I like the rene herse calculator https://www.renehersecycles.com/tire...culator-intro/
How much accuracy is necessary?
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