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Rolling resistance ratings and tire wear

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Rolling resistance ratings and tire wear

Old 06-26-22, 06:46 AM
  #26  
GhostRider62
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I never measured but always assumed thinner thread makes for lower Crr. Why? The TT versions of popular tires come from the factory with thinner thread. I also assumed that a worn front tire would ruin the aerodynamics and rolling resistance increases after a puncture.

My current GP5000 S tubeless rear tire is very worn owing to supply chain issues, increases in prices, and my lack of money. I am curious if my rolldown testing method would detect the difference between this old tire and the new one awaiting my lazy hands to install it. I can easily measure the difference between a latex and butyl tube on the same tire.

I do not understand why thinner rubber tread is slower.
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Old 06-26-22, 09:48 AM
  #27  
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Originally Posted by GhostRider62 View Post
I do not understand why thinner rubber tread is slower.
Unless the tire has really thick tread and knobs, most of the rolling resistance isn't because of the tread per se, nor the size of the contact patch. It's not the compression of the tire where energy is lost, it's the *rebound* from the compression. Low rolling resistance tires rebound better, so they lose less energy and return more to the bike system. Have you noticed that tennis balls, basketballs, golf balls, etc., become less bouncy over time? Tread thickness, and contact patch size, and weight, and other characteristics of tires that are easy to see or measure turn out to have some influence on rolling resistance, but more important is how well they rebound and return energy rather than absorb it. As tires wear and age, they rebound less well.

[Edited to add:] If you (mistakenly) think that most of the sources of tire losses are from compression, you try to minimize the compression: so you inflate thin tires to high pressure, which reduces the contact patch. However, latex tubes produce lower rolling resistance than butyl tubes, and they don't affect contact patch or compression. What they do is rebound better. Thick tire treads last longer and may be safer, but it turns out that pneumatic tires have lower resistance than solid rubber tires because air under pressure is a better "spring" than solid rubber so they rebound better. So in a big picture sense, you're right, thinner tread doesn't have higher rolling resistance than thicker tread--but since the bigger source of loss is elsewhere, the overall rolling resistance can increase even though the tread is thinner. They go in opposite directions but the loss with tire wear and age is greater than the gain from thinner tread.

Last edited by RChung; 06-26-22 at 10:19 AM.
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Old 06-26-22, 12:15 PM
  #28  
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Originally Posted by Toadmeister View Post
Thatís not what your mother said last night, Trebeck!
It's good to know she's still leading an active life.....
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Old 06-26-22, 12:41 PM
  #29  
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Originally Posted by RChung View Post
Unless the tire has really thick tread and knobs, most of the rolling resistance isn't because of the tread per se, nor the size of the contact patch. It's not the compression of the tire where energy is lost, it's the *rebound* from the compression. Low rolling resistance tires rebound better, so they lose less energy and return more to the bike system. Have you noticed that tennis balls, basketballs, golf balls, etc., become less bouncy over time? Tread thickness, and contact patch size, and weight, and other characteristics of tires that are easy to see or measure turn out to have some influence on rolling resistance, but more important is how well they rebound and return energy rather than absorb it. As tires wear and age, they rebound less well.

[Edited to add:] If you (mistakenly) think that most of the sources of tire losses are from compression, you try to minimize the compression: so you inflate thin tires to high pressure, which reduces the contact patch. However, latex tubes produce lower rolling resistance than butyl tubes, and they don't affect contact patch or compression. What they do is rebound better. Thick tire treads last longer and may be safer, but it turns out that pneumatic tires have lower resistance than solid rubber tires because air under pressure is a better "spring" than solid rubber so they rebound better. So in a big picture sense, you're right, thinner tread doesn't have higher rolling resistance than thicker tread--but since the bigger source of loss is elsewhere, the overall rolling resistance can increase even though the tread is thinner. They go in opposite directions but the loss with tire wear and age is greater than the gain from thinner tread.
Thank you. Aged and degraded thread makes sense. Tires would typically be on my bike for 2 months max and being a chicken, I never wore them down although I am slightly annoyed how fast the GP5000 S tubeless wear compared to the clincher version. I was thinking quietly to myself that the casing threads break and the overall restoration of energy would be lowered. I can see this on Compass EL aka Hearse tires, even pinching too hard can break sidewall threads.
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Old 06-27-22, 01:31 PM
  #30  
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Ian Simms that started Greenspeed did a lot of research and found that a 20 inch wheel had the least rolling resistance.
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Old 06-27-22, 02:00 PM
  #31  
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Originally Posted by rydabent View Post
Ian Simms that started Greenspeed did a lot of research and found that a 20 inch wheel had the least rolling resistance.
That's interesting. Do you have any details on how he did that research?
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Old 06-27-22, 02:15 PM
  #32  
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Originally Posted by Steamer View Post
So where's the data?

The data present here supports the opposite of your assertion.
I believe the data has been published by Bicycle Quarterly, though I don't have a reference. The data presented here is without statistical analysis. It could be that all the numbers are the same regardless of mileage on the tire. Without the statistics, there is no way to know.
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Old 06-27-22, 03:17 PM
  #33  
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Originally Posted by rydabent View Post
Ian Simms that started Greenspeed did a lot of research and found that a 20 inch wheel had the least rolling resistance.
Greenspeed scorcher is the fastest 406 tire or at least many claim based on testing although there is a Continental tire made with the same casing and rubber as the Supersonic that is supposedly faster.

I've owned a few 406 and 451 20 inchers and am skeptical to be frank and if it was BQ doing the testing, I feel confident saying BS.
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Old 06-30-22, 01:16 PM
  #34  
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Too little to measure or to matter. The work you do is to overcome air drag from your body. Tires have gotten wider even for the pro riders with the realization that skinny tires does not translated into a significant reduction in rolling resistance.
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Old 06-30-22, 04:55 PM
  #35  
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Interesting points in the replies. I like 28" wheels, tires with sleek pattern and I swear hard pumped tires roll better. New tires are always nice but I have not tought much about the tubes, maybe I should? Neither have I thought much about the inner weave weaken or becomming less bouncy with age. I wear my tires out, thinking it is economical and less waste and I just live with the situation until I get a new pair or I need new for different conditions. Some tires have complex layers of different rubber compounds. I think Schwalbe had a test showing that the harder most durable rubber gives less rolling resistance compared to the softer type giving best grip. Some tires have the same rubber all the way to the kevlar or inner nylon weave, maybe wear affects rolling resistance less then.
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Old 06-30-22, 05:44 PM
  #36  
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Originally Posted by Calsun View Post
Too little to measure or to matter.
Elsewhere I've posted a list of almost every cycling argument. This is #3:
3. Things I can't see, can't measure, or don't care about aren't important.
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Old 06-30-22, 07:11 PM
  #37  
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Originally Posted by Calsun View Post
Too little to measure or to matter. The work you do is to overcome air drag from your body. Tires have gotten wider even for the pro riders with the realization that skinny tires does not translated into a significant reduction in rolling resistance.
Maybe not significant to you.

Reduction of rolling resistance is the best, cheapest, and quickest bang for the buck in terms of increasing speed for the average joe. I would say nothing matters as much, meaning you are 100% wrong.
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Old 07-01-22, 04:19 PM
  #38  
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Originally Posted by GhostRider62 View Post
Reduction of rolling resistance is the best, cheapest, and quickest bang for the buck in terms of increasing speed for the average joe.
A real world example:

What does upgrading from, say, Vittoria Zaffiro Pro G+ 2.0, to say, Vittorial Corsa Speed G+ 2.0 get you?

According to bicyclerollingresistance.com, at 18 mph the power load difference for two tires would be 17.6 Watts.

And you'd have to spend about $60 extra for the upgrade.

Seems like a pretty good deal!
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Old 07-01-22, 05:44 PM
  #39  
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Originally Posted by terrymorse View Post
...And you'd have to spend about $60 extra for the upgrade.

Seems like a pretty good deal!
We spend this on a good racer when any improvement matter. I'm not sure the priority is there for a commuter or touring situation when other factors like puncture resistance enters into the picture. How much do we feel or notice the 17,6 Watts difference if time and speed are not of absolute essence?
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Old 07-01-22, 05:57 PM
  #40  
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Originally Posted by Mickey2 View Post
We spend this on a good racer when any improvement matter. I'm not sure the priority is there for a commuter or touring situation when other factors like puncture resistance enters into the picture. How much do we feel or notice the 17,6 Watts difference if time and speed are not of absolute essence?
This is a variant of point #3 in post 36 above: "If it's not important to me, it needn't be important to anyone else; and if it *is* important to you, then you don't count."
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Old 07-01-22, 06:07 PM
  #41  
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Originally Posted by Mickey2 View Post
How much do we feel or notice the 17,6 Watts difference if time and speed are not of absolute essence?
According the the Kreuzotter calculator with default settings, going from 160 Watts to 177.6 Watts increases your speed by about 4%.

Is a 4% speed gain at the same effort, or a 4% reduction in required effort at the same speed, worthwhile?
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Old 07-01-22, 06:29 PM
  #42  
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Originally Posted by terrymorse View Post
...

Is a 4% speed gain at the same effort, or a 4% reduction in required effort at the same speed, worthwhile?
In a race no doubt. In a relatively short, every day ride; negligible. In every day communting it might save a couple of minutes. I doubt the difference will leave many of us any more or less exhausted in the long run. To RChung, I will argue rolling resistance matter on all types of bikes, one factor in a tuned up bike that makes a noticeable difference. I agree though, the minor things we might as well not spend much energy on.
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