Interesting Article on Tire Testing/ Results

[firerescuefin]

http://www.cyclingnews.com/features/tech-feature-the-work-of-wheel-energy


If there was ever an article for this forum....actually pretty interesting.

[Germany_chris]

Cutoff is. I ride 25's on most of my bikes some if they'll fit get 28's I'v never really noticed a difference. I wonder if then 32's roll as well as 25's.

[AngryScientist]

interesting article i admit, but it is definitely lacking in details.

Re: wider tires roll faster - the article says all other things being equal...including i presume tire pressure... the article points to tire deformation being the cause of most power to pavement loss, but naturally you would run higher pressure in a 23 tire than a 25, so why would things ever be equal? does that completely negate the advantage or some other result? who knows??

it is interesting that there is an outfit out there independently testing stuff, and tire manufacturers are working with them to design better tires. my take-away is that as long as i'm buying major brand tires who actually do or subcontract out R&D, i should have the best tires available.

[Steve in SLO]

According to this, 25c tires and latex tubes may be the way to go.
It would be interesting to see what the data shows on 28c tires.

[RPS]

Cutoff is. I ride 25's on most of my bikes some if they'll fit get 28's I'v never really noticed a difference. I wonder if then 32's roll as well as 25's.
Not only that, but how is optimum affected by rider size. It's hard to think that what works best for a 200-pound guy is the same as a 120-pound lady.

[RPS]

Re: wider tires roll faster - the article says all other things being equal...including i presume tire pressure... the article points to tire deformation being the cause of most power to pavement loss, but naturally you would run higher pressure in a 23 tire than a 25, so why would things ever be equal? does that completely negate the advantage or some other result? who knows??

That was my first question when reading the article. I've tried larger tires with equal pressure and couldn't stand them because they rode so harsh. Seldom is everything equal.

[nm87710]

...but it is definitely lacking in details.

?

[BengeBoy]

Re: wider tires roll faster -

Bicycle Quarterly has been saying the same thing for several years now.

Worth buying some of their back issues on tire tests if you're interested.

[endosch2]

I am curious what Latex tubes people use - the last time I tried them was 20 years ago in a mtn bike and they lasted one ride. They leaked at the valve stem. What are the good ones?

[nm87710]

I am curious what Latex tubes people use - the last time I tried them was 20 years ago in a mtn bike and they lasted one ride. They leaked at the valve stem. What are the good ones?

Michelin

[false_Aest]

Latex:

Michelin, Challenge, Vredenstein (however you spell it). They're all awesome for race day.

I commuted and trained on them for 8 months. I'm not sure that it was the best $$ spent. I'd rather be 10% slower or whatever during the week only to get that 10% back on the weekend. Dig?

Talc em good though. Talc em good.


Over the past 8 months or so I've futzed with my tyre pressure about 8 times (each change I've ridden for about 1 month).

My conclusion is this (I'm 145-150lbs riding a Caad9 with Kinlin 270s laced to 28H DA hubs 2x(Revolutions) front 2x/3x(competition) rear): I'm faster and more comfy dropping my tire pressure to ~90/95 but my rear tyre wears faster. My solution is again to train/commute at 100/105 and to race at the lower pressure.

All the 3rd-party n3rding in the world couldn't answer that question for me. I had to answer it myself. (And even if its numerically/mathamatically wrong it *feels* right and for schlubs like you an me that's probably all that matters).

[rugbysecondrow]

Bicycle Quarterly has been saying the same thing for several years now.

Worth buying some of their back issues on tire tests if you're interested.


David Kirk has also been saying this for a while, in fact there is a thread with some a strong and compelling discussion in favor of larger tires.

I am not sure what the cut-off would be.

[fourflys]

David Kirk has also been saying this for a while, in fact there is a thread with some a strong and compelling discussion in favor of larger tires.

I am not sure what the cut-off would be.

unfortunately the cutoff is usually 25's because of the narrow-minded thought that EVERYONE should run 23's because that's what the pros ride and thus most bikes are built around that...

BTW- I love my Pro2 race 25's...

[1centaur]

I'd like to see a translation of rolling resistance to watts (so we can compare with ceramic bearings, for example) and it looks like that machine does not correct for the aerodynamic properties of tires/width.

[Aaron O]

Does this also mean the old 27inch wheels are worthwhile afterall?

PS...who wants to buy a pair of 700x20c foldable veloflex pave records?

[endosch2]

Latex:

Michelin, Challenge, Vredenstein (however you spell it). They're all awesome for race day.

I commuted and trained on them for 8 months. I'm not sure that it was the best $$ spent. I'd rather be 10% slower or whatever during the week only to get that 10% back on the weekend. Dig?

Talc em good though. Talc em good.


Over the past 8 months or so I've futzed with my tyre pressure about 8 times (each change I've ridden for about 1 month).

My conclusion is this (I'm 145-150lbs riding a Caad9 with Kinlin 270s laced to 28H DA hubs 2x(Revolutions) front 2x/3x(competition) rear): I'm faster and more comfy dropping my tire pressure to ~90/95 but my rear tyre wears faster. My solution is again to train/commute at 100/105 and to race at the lower pressure.

All the 3rd-party n3rding in the world couldn't answer that question for me. I had to answer it myself. (And even if its numerically/mathamatically wrong it *feels* right and for schlubs like you an me that's probably all that matters).


What do you use? Baby Powder as the Talc?

[Ralph]

And there are advertised widths and real widths depending on rim width. How do you factor that in?

Some 700X23 Michelin PR2's of mine on IRD rims measure 24MM wide, and these are fairly narrow rims.

I have some Conti Ultra Gatorskins 700X25 on wider Campy box roms, and these also measure 24MM wide. ????

[rugbysecondrow]

I suppose we could pick apart the summary of the study, but I wouldn't assume that since a detail was left out of the summary that it was left out of the analysis. If you scroll through the photos for instance you will see much more detail than the article discusses, I imagine there is much more behind that as well. It would be interesting (this being relative) to read the full study.

[unwell_ultra]

Bicycle Quarterly has been saying the same thing for several years now.

Worth buying some of their back issues on tire tests if you're interested.

Bicycle Quarterly Volume 5, Number 1, Autumn 2006 (No. 17) has several good articles regarding tires. The performance of tires, how they test tires and the physics of tire rolling resistance.

The tire tests are dated but overall the articles are still informative.

[forrestw]

Sounds to me like an advert for the testing company and the tire companies using their services.

The two useful tidbits seem to be

a. rolling resistance is at odds with puncture resistance
b. thin / latex tubes may have more benefit than all other vbls

My LBS knows advises the former, the latter is pretty obvious.

When / if they publish some actual test procedures / numbers it might be interesting. Detailed data has been collected before, down to we know that the contact adhesives used to glue sew-ups are responsible for quantifiable Crr component. This 'research' also fails to consider wind resistance which predominates over rolling at any appreciable speed anyhow.

Meantime I will continue to assume that iff you properly inflate a 23 (if you use Sheldon's numbers you come out at higher pressure than nearly all riders use across the board) it will have lower RR than a 25 and if you're riding on rough terrain, the 23 may not be your best bet.

I like 25s but mostly ride on 23s because that's the only size that the suppliers are carrying in the tires that I find run best (current fav being Swalbe Ultremo).

Sorry for being pissy, hack journalism being presented as scientific bothers me :-).

[soulspinner]

Not only that, but how is optimum affected by rider size. It's hard to think that what works best for a 200-pound guy is the same as a 120-pound lady.

someone gets this concept! :beer:

[vjp]

What do you use? Baby Powder as the Talc?

I always use baby powder, then when my wife asks why I smell like a stripper I can say I was changing my tubes.

[mcteague]

I always use baby powder, then when my wife asks why I smell like a stripper I can say I was changing my tubes.
And why would she know that? :rolleyes:

Tim

[fogrider]

pretty interesting, but it looks like the testing of the ccr was done with a large steel wheel, not asphalt...I'm thinking its pretty tough to put asphalt on a spinning wheel but I'm thinking the results might be a little different.

and still no testing of tubular tires...the mystery continues...

[rugbysecondrow]

pretty interesting, but it looks like the testing of the ccr was done with a large steel wheel, not asphalt...I'm thinking its pretty tough to put asphalt on a spinning wheel but I'm thinking the results might be a little different.

and still no testing of tubular tires...the mystery continues...
They used all types of terrain in their tests.

[Rueda Tropical]

Problem in finding the point of diminishing returns in tire width is getting an apples to apples comparison. The Schwalbes Ultremos might make a good test because the only variable is width, same tread, same casing, etc., in 23, 25 and 28.

Then as was pointed out you have rider weight. A heavier rider will require a wider tire to get the same effect as a lighter rider and to be able to use a similar PSI.

As to aero, rims are not made to give an aero profile to tires wider then 23 but the step up to 25 is pretty small with some 23's measuring 24 or 25 on a 23 rim anyway.

From Torelli:
"There is a view that a 20 mm width tire is faster than a 23 by virtue of its smaller cross section and lighter weight. Interestingly enough, this is not true. The people making the Torelli tires had noticed that the pro teams that they sponsored asked for 23s because they felt they were faster. When they investigated and did the testing, they found that the riders were correct."

Vroomen from Cervelo on wider tires (http://www.bikeradar.com/news/article/cervelo-testteam-get-testing-in-belgium-25190)

[Gat64]

This might be of interest:

"After all this testing, we now can say with great certainty that increasing your tire pressure (beyond a certain point) does not make your bike faster on road surfaces that range from very rough to very smooth. In fact, on very rough road surfaces, higher pressures are a lot slower than lower pressures, because the suspension losses are so great. On most surfaces, tire pressure (beyond a certain point) simply doesn’t make a difference in speed."

"Our initial tests even established at what point the performance no longer increases with higher tire pressures. For most tires and on “average” roads, this point appears to be a little higher than the 15% tire drop measured by Frank Berto."

Article: http://janheine.wordpress.com/2010/10/18/science-and-bicycles-1-tires-and-pressure/

[mpetry]

Back before the dawn of recorded history - 1999 or so - Jobst Brandt did a tire test for rolling resistance at a range of inflation pressures.

http://www.sheldonbrown.com/brandt/images/rolling-resistance-tubular.gif

I think the graph speaks for itself. As inflation pressure is increased beyond about 90psi, the reductions in rolling resistance are diminished.

Units Conversion: 8 Kg/cm^2 = 14.22 PSI so 8 on the chart is about 113 PSI

The full article is archived on the Sheldon Brown memorial website

Jobst Brandt Tire Test (http://www.sheldonbrown.com/brandt/rolling-resistance-tubular.html)

Mark Petry
Bainbridge Island, WA

[Gat64]

Interesting that the Avocet 30 and 20 in 28C size measures better than the 25C versions... by a very slight margin.

Thanks for the diagram.

[RPS]

This might be of interest:
....snipped.....
Article: http://janheine.wordpress.com/2010/10/18/science-and-bicycles-1-tires-and-pressure/
Interesting. The article would suggest much depends on the bike too. A smoother bike should not have the same suspension losses.

The next step was to develop a hypothesis that explained what we had observed: Suspension losses are caused by friction in the the rider’s body tissues as they are vibrating. Higher pressures cause more vibrations, and hence higher suspension losses. This appears to cancel any gains at higher pressures from reduced flexing of the tire (hysteretic losses), as the tire deforms less at the contact patch as the wheel rotates.

This hypothesis also allowed us to explain why the drum test results were different – by neglecting the suspension losses, they measured only one half of the equation.