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A wheelist
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Ahhh jeeze here we go again. Thousands of bike riders will be sitting around laptops, looking for the holy grail, instead of where the real gains are - out there riding.
 

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Forever a Student
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10 of the best performance road tires lab tested - BikeRadar

Ben Delaney said:
The point is, among the best tires, environmental factors can easily play more of a difference than small, lab-measured rolling resistance differences, even on days with virtually no wind.

As a 185lb rider, I’ll continue to run my tires between 80 and 100psi for everyday riding — I’m happy to pay one or two watts for more comfort and grip. I can’t feel the loss of one or two watts, but I can feel the difference in 40psi in cushioning.

For racing, I’ll still pump my tires up to 110psi or so.


Finally, since wider tires roll faster and more comfortably, I won't ever buy a 23mm tire again.
 

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Matnlely Dregaend
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The conclusion I reached after watching and reading the article was that there was no actual discernible difference on the road between the tires. And that Specialized was full of $hit when they said lower pressures are faster.
 

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Ahhh jeeze here we go again. Thousands of bike riders will be sitting around laptops, looking for the holy grail, instead of where the real gains are - out there riding.

Repped! :thumbsup:
 

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Discussion Starter · #6 ·
but quality of a tire should also be more than just rolling resistance. Handling becomes very important under heavy braking too (and this is where I personally think the Conti GP4000s are crap)

But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.
 

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It may be the best available, but I don't find that the rough drum comes close to replicating the roads I ride. I always thought the idea of the softer tire conforming to the road was speaking to cracks, not just a roughness to the asphalt.
 

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But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.
Nonsense. Suspension losses increase with pressure and will eventually be larger than the improvements due to reduced hysteresis (casing and rubber flexing) losses.

Starting with a very low tire pressure, total losses decrease as you increase tire pressure, then bottom out, and then rise again as suspension losses become predominant. This is well documented. In most cases, the sweet spot ranges from roughly 80-110 psi (5.5-7.6 bar). This will obviously vary with road roughness, rider weight, tire casing quality, tread rubber hardness, etc.
 

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It may be the best available, but I don't find that the rough drum comes close to replicating the roads I ride. I always thought the idea of the softer tire conforming to the road was speaking to cracks, not just a roughness to the asphalt.
Agreed, I would hardly consider diamond plate steel a suitable model for rough road surfaces- at least for the roads in my area. I've got some chip seal roads around where I live that will rattle your teeth out even when using wide rims and 25c tires at lowish pressures. How hard would it be to make a very realistic test drum with actual chip seal applied?
 

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Discussion Starter · #10 ·
Nonsense. Suspension losses increase with pressure and will eventually be larger than the improvements due to reduced hysteresis (casing and rubber flexing) losses.

Starting with a very low tire pressure, total losses decrease as you increase tire pressure, then bottom out, and then rise again as suspension losses become predominant. This is well documented. In most cases, the sweet spot ranges from roughly 80-110 psi (5.5-7.6 bar). This will obviously vary with road roughness, rider weight, tire casing quality, tread rubber hardness, etc.
80-110 psi is not what I would call "starting with low pressure". I've read people on RBR throwing out numbers 60-70 psi for best rolling resistance, and this is out of your sweet spot.
 

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80-110 psi is not what I would call "starting with low pressure". I've read people on RBR throwing out numbers 60-70 psi for best rolling resistance, and this is out of your sweet spot.
You read his post wrong. Didn't give any figure for starting at low pressure, that was just to give a starting reference to describe behavior as pressure increases between extremes.
 

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80-110 psi is not what I would call "starting with low pressure". I've read people on RBR throwing out numbers 60-70 psi for best rolling resistance, and this is out of your sweet spot.

General and misleading statement. As we all well know and what Kerry stated, that would depend on tire width, rider weight, intended use, etc. While 80-110 PSI might be an ideal range of pressure for 25c tires ridden by a 185lb. rider on average roads, it wouldn't be an ideal range if you change any of said variables - tire width, rider and bike weight, road conditions.

So 60-70 PSI may very well be your ideal pressure for 32c tires ridden on chip seal by the same rider.

As the saying goes, YMMV. And I really doubt that +/-10 PSI will affect rolling resistance very much. So -10 or even -20 PSI from that "rolling resistance sweet spot" for better comfort and handling may very well be a wise choice.
 

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A wheelist
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General and misleading statement. As we all well know and what Kerry stated, that would depend on tire width, rider weight, intended use, etc. While 80-110 PSI might be an ideal range of pressure for 25c tires ridden by a 185lb. rider on average roads, it wouldn't be an ideal range if you change any of said variables - tire width, rider and bike weight, road conditions.

So 60-70 PSI may very well be your ideal pressure for 32c tires ridden on chip seal by the same rider.

As the saying goes, YMMV. And I really doubt that +/-10 PSI will affect rolling resistance very much. So -10 or even -20 PSI from that "rolling resistance sweet spot" for better comfort and handling may very well be a wise choice.
Just to chuck in an anecdote about tire pressure, tire pressure variation and surface smoothness in here. It's not totally relevant to the topic but I always found the observation interesting -

7-10 years ago I rode an indoor board track for training and I used Conti Supersonic tires inflated to 130psi. The track surface was smooth plywood. As there were almost no other variables (certainly not wind direction and surface variability anyway) it was very apparent when my tires were not pumped to 130psi. It felt like I was pedaling in cement. It's not often I didn't re-pump before every session but at the times that I did forget, it wasn't many laps before I'd be off the track and topping up the tires.

I once switched tires to some Vreds and they were so bad, compered to my Contis, I switched them back in the track center, before 15 minutes passed. Again, it was like pedaling in cement. All subjective? Yeah maybe.
 

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Matnlely Dregaend
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I might point out that train wheels work on this same principle, and the rolling resistance for said train wheels is incredibly low (Crr of .001!). I'm going to insist on rails being installed on every bike path.

 

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But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.
Ponder this 'science' next time you roll a shopping cart across the rough asphalt parking lot at the grocery store.
 

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Discussion Starter · #19 ·
Just to chuck and anecdote about tire pressure, tire pressure variation and surface smoothness in here. It's not totally relevant to the topic but I always found the observation interesting -

7-10 years ago I rode an indoor board track for training and I used Conti Supersonic tires inflated to 130psi. The track surface was smooth plywood. As there were almost no other variables (certainly not wind direction and surface variability anyway) it was very apparent when my tires were not pumped to 130psi. It felt like I was pedaling in cement. It's not often I didn't re-pump before every session but at the times that I did forget, it wasn't many laps before I'd be off the track and topping up the tires.

I once switched tires to some Vreds and they were so bad, compered to my Contis, I switched them back in the track center, before 15 minutes passed. Again, it was like pedaling in cement. All subjective? Yeah maybe.
you ain't alone in feeling this cement. When I switched to using 25mm tires on 25mm rims, I thought I would give the "low pressure" revolution a go. Being that I as under 120 lbs, so I pump it to 60 psi front, 70 psi rear. The theory is that if guys who were much heavier than me saying they were running 70-75 psi on 25c/25mm, I could try 60/70 psi. Pavement here is smooth, nice road overall. During regular dronning in zone3/4 it was fine. But when I went to sprint, especially sprinting up a slight incline, all of the sudden, I felt like the whole bike, both front and rear ends, started to give sideways, taking all confidence in wanting to continue to hammer further. After that, pumped the pressure up to 80/90 front/rear and the swishy-swoosh pretty goes away.
 
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