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Tire rolling resistance test (again)

10K views 92 replies 24 participants last post by  Lombard 
#1 ·


the conclusion is 25mm tires with HIGHER pressure for lowest rolling resistance.
 
#5 ·
Repped! :thumbsup:
 
#3 ·
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.
 
#4 ·
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.
 
#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.
 
#8 ·
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.
 
#9 ·
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?
 
#16 ·
#17 · (Edited)
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.

 
#22 ·
I am not racing and shaving a possible millisecond off of my ride does not matter to me. To me, how the ride feels is what is important.
Having said that, Mike T, ACL - understanding and agreeing that you should ride what feels best, did those feelings of riding in cement translate into any sort of actual change in performance? Isn't that the whole purpose of the video?
 
#23 ·
How can I, using an indoor track to get in the miles (I know I did a few hundred thousand laps) measure "actual change in performance?" Oh for sure it felt like it was harder to hold 40kph (24mph?) with the lower pressure but short of doing powermeter work or gathering lots of data on track average speeds with both sets of tires at varying pressures, we have no reliable evidence other than "it feels like" - which is not all that bad for us normal people. It might not wash with Team Sky or someone going for the hour record but it's good for me.

As I said before, an indoor board track negates some of the variables that we encounter out on the road where we can never be truly sure whether it's the road surface, wind direction, tire compound or pressure that's making us pedal in cement or zing along.
 
#27 ·
I call it tire squirm, and it definitely affects performance. Some tires are more prone to it than others and rim width will also play a part.

Thats why it's a good idea to put 5-10 extra psi in your rear tire for a hill climb, more weight on rear and high torque in low gear at lower cadence will cause extra squirm/ squish.

Similarly, some sprinters will encounter this at high force accelerations and throwing weight around. Need to put in a few extra psi to stop it if it's happening.

we put a bit more air in front tire than expected from weight distribution because downhill cornering can put very large forces on the front tire and cause it to flop, impairing handling.

The outdoor tire tests were done below 10 mph on flagstaff mountain, grades between 7-10%. Probably the worst way to test rolling resistance and will not give useful results. What he showed is that there isn't much of a difference between tires on a hill climb.
 
#41 ·
Are you suggesting that the current Gran Prix 4000 IIs has sidewall integrity issues?

I'd like to see some actual statistics that bare that out.

Sure, there were some reports of damaged sidewalls on the original 4000's, but I haven't seen anything reported recently about this, and considering that the 4000 II (and 4 season) are the two most popular tires on the planet, I really don't know how you can suggest they have issues like this.

I don't know anything about Vred's, so I obviously can't compare. I'm glad you are happy with your tire choice.

I've got about 20k miles over the last few years on 4000II's and 4 Seasons - I've gone through quite a few of them, but none due to any kind of premature failures, and I rarely get flats of any kind.

Any tire can suffer a sidewall cut. It happens to the best tires. Some are certainly more prone than others. I'd rank the Continental tires pretty high up on the list of durable tires - even the 4000 II race tires.
 
#44 ·
Another Vred TriComp Fortezza fan here. Have nothing but good to say about them, both handling and wear. Have gotten some good prices for them at Ribble over the years.

But as of late I've been riding a bike with 650b wheels and tires and no Vreds in the size so I went to Compass tires, and have really been happy with them. Some of the best tires I've ridden, but considering the size difference I can't really compare them to the Vreds I've been riding(Vred 700c\23 & 25mm and Compass 650b\42mm), but I put a set of Compass 700\32mm tires on my wives bike and if she has the same good luck I'll try them on my 700c bikes when the time comes.

The smallest Compass 700c tire is 26mm. There is no flat protection and they're a mite pricey, but, in the 650b\42mm that I've been riding I have found them to be outstanding. I mentioned no flat protection, but that has not been an issue in the 42mm tires. I don't know how that will translate to my wives 700\32mm or the 700\26 or 28mm that I would have to use on my bikes that are currently shod in the Vreds, but I have high hopes.

https://www.compasscycle.com/product-category/components/tires/700c/
 
#53 ·
Flat protection is probably the last thing on my mind when choosing tires. I've been using gp4000IIs for 3 years without issues. Almost all the flats have been from hitting objects in the road which would have flatted any other tire as well. I tried some S Works tires last year but they felt slower and I ended up going back to the gp4000IIs. If you wait for the sales they have on the different websites the prices aren't that bad either.
 
#54 ·
I have been using Vredestein Fortezza Senso All Weather 25mm tires mounted to Campagnolo Bora C17 rims for over 2 years now. I have had exactly one puncture flat from a small piece of glass imbedded in the tread during that time period. So one flat in approximately 10,000 miles.
I also have Continental GP4000S II 23mm tires mounted to Campagnolo Shamal clinchers that have experienced no puncture flats in several years.
I use butyl tubes inflated to 90-100 psi and change my tires when they start to get squared off.
The Continentals scored high for rolling resistance and the Vredesteins were one of the worst for rolling resistance. However I consider other factors such as handling and puncture resistance more important.


Sent from my iPhone using Tapatalk
 
#56 ·
I had a sidewall failure on a GP 4000 IIs. It was a 10 mm long tear at the junction of the bead and the sidewall itself. I have no doubt that it was due to a manufacturing defect. It failed after about 2 weeks (200 miles) of riding.

There were no burrs on the rim which might have caused this failure. The tire was replaced by Bike Tires Direct where I bought it.

I have gone through 3 of them in the past two riding seasons. No issues with any others. The replacement for the one that failed is getting close to end of life with no repeat performance.
 
#58 · (Edited)
Given the tables in the article:





Given the slopes of the lines, I have a very hard time understanding how there would be a pressure high enough where the overall energy loss would begin to increase again within the max tire pressure spec. Given that the bike doesn't significantly heat up, any "lift" loss would immediately be returned by gravity. The idea that the human body dissipates frictional heat due to this "lift" is impossible to disprove but seems incredibly unlikely as well. I agree that riding around on 130psi tires may well be uncomfortable, but lots of very light pros ride this pressure and seem to survive grueling 6 hour rides. Also modern components (especially carbon seatposts and bars) are much more compliant and make the ride smoother despite rock hard tires. I tend to ride 105-110psi because at lower pressures I hate the squirmy feel when pushing hard in or out of the saddle, plus I'm lazy and tend to pump up my tires every other, not every day. And of course I don't weigh 125 lbs.

Also given fundamental aerodynamic principles. if you take the same shape and make it narrower (from the front anyways), it will always have a better aerodynamic profile. No matter what wheel manufacturers may say , somehow they aren't comparing apples to apples. Maybe other people experience lots of crosswinds, but God seems to not like me and blasts wind directly in my face.
 
#61 ·
Given the tables in the article:
...I have a very hard time understanding how there would be a pressure high enough where the overall energy loss would begin to increase again within the max tire pressure spec.
There are many problems with correlating tire rolling resistance on round drums with real world conditions on rough surfaces. And the author quoted by the OP did his real world testing comparing one tire against the other. He never tested the same tire at different pressures in the road tests.

The best test for rolling resistance uses real world conditions, power meters, and average many runs. I found a test that did this for MTB tires. This confirms what many have been saying already - if you have super smooth roads, there is a rolling resistance benefit to higher pressures. As the surface gets more uneven, the benefit goes to lower pressure, to a point.
Mountain Bike Tyre Rolling Resitance

Their results - "reducing tyre pressures does not just leave rolling resistance more or less unaffected, as can be heard here and there, but actually reduces rolling resistance! This is true even on level paths of fine gravel, but the rougher the ground, the greater the effect,"

 
#65 ·
Exactly. The diamond patterned drums simulate roads without imperfections at best. Throw in some imperfections, cracks, broken pavement, chip seal or other real world conditions and you have gone beyond what any of these tests have shown.
 
#81 ·
There are literally gravity batteries that function on this fundamental physics principle. Energy spent moving an object upward against gravity is ALWAYS returned when it comes back down. A bouncing ball loses no energy in it's vertical motion, it loses it only through compression of the ball itself and through aerodynamic loss, plus loss by deformation of the surface it bounces upon.
 
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