Great tire test article!

[Ken Robb]

Then there are the tests that have shown that the specific tire/pressure combo that was best on a smooth drum was not best on a textured surface like a typical paved road so this test won't influence my choice of tires. Heck, I'm old and slow no matter what tires I use so comfort and puncture resistance mean a lot to me.

[Mark McM]

Originally Posted by Ken Robb

Then there are the tests that have shown that the specific tire/pressure combo that was best on a smooth drum was not best on a textured surface like a typical paved road so this test won't influence my choice of tires. Heck, I'm old and slow no matter what tires I use so comfort and puncture resistance mean a lot to me.

Tire drum rolling resistance information (smooth or otherwise) can still be very useful for tire selection - even for real world tire selection.

Modern ideas on tire rolling resistance break down losses into two categories: Tire hysteresis losses, and system vibration losses (which Jan Heine calls "suspension losses" and Josh Poertner calls "impedance"). Drum testing can determine hysteresis losses, although not system vibration losses. See Josh Poertner's post on this subject:

https://silca.cc/blogs/journal/part-...-and-impedance

The results of drum and real world testing have repeatedly shown that the relative order of rolling resistances between tires is maintained on different surfaces, even if the absolute magnitude of rolling resistance changes. In other words, if tire A has lower rolling resistance on a smooth drum than tire B, than tire A will also have lower rolling resistance on a rough road than tire B, even if the rough road resistance is higher for both.

So yes, even if you don't actually ride on smooth drums, smooth drum tests data will still show you which tire will have the lowest rolling resistance on your bumpy roads.

[Gummee]

Originally Posted by KSCycling

I'd like to see research on grip, for the purposes of Criterium racing. Also, what about wind tunnel testing and crossing the research between the drum test and the wind tunnel. My wide designed carbon wheel recommends a size 23mm tire for aerodynamics vs a 25mm.


Sent from my iPhone using Tapatalk

this

There's lots of older wheel designs out there that were designed around 23c tires...

I'm curious who's 'the best' all-round.

M

[KSCycling]

Originally Posted by Mark McM

http://flocycling.blogspot.com/2016/...ire-study.html

Great info!

[stephenmarklay]

Fun to read. However, it seems like the bicycle rolling resistance guy has more comprehensive data. He however does not use a rough drum. It does appear that most of the results are pretty similar.

http://www.bicyclerollingresistance.com

[oldpotatoe]

Originally Posted by stephenmarklay

Fun to read. However, it seems like the bicycle rolling resistance guy has more comprehensive data. He however does not use a rough drum. It does appear that most of the results are pretty similar.

http://www.bicyclerollingresistance.com

I find this type of info 'interesting' but note that the differences between the 'fastest' and 'slowest' is teeny. Like a lot of things bike, unless the tires are just sluggish dogs(like a Conti Contact, IMHO), reliability is more important, IMHO.

[Rusty Luggs]

I find it interesting that most of these articles do not seem to support the notion that lower pressure = lower rolling resistance, except on exceptionally rough road surfaces

[Pastashop]

Originally Posted by Rusty Luggs

I find it interesting that most of these articles do not seem to support the notion that lower pressure = lower rolling resistance, except on exceptionally rough road surfaces

Jobst Brandt had argued that lower pressure is slower, period. Part of Jan Heine's hypothesis was that vibrations propagated into the rider are ultimately dissipative (that is, a source of energy loss), not to mention contributing to fatigue. I've not seen definitive measurements done that are sufficiently free of confounding factors to convince me either way. And I'm too cheap and time crunched to invest in a power meter and do my own experiments.

[ColonelJLloyd]

Originally Posted by oldpotatoe

I find this type of info 'interesting' but note that the differences between the 'fastest' and 'slowest' is teeny. Like a lot of things bike, unless the tires are just sluggish dogs(like a Conti Contact, IMHO), reliability is more important, IMHO.

Comfort or "feel" is another significant criteria. The difference between a 28mm high end Vittoria and a Gatorskin is significant to me.

[monarchguy]

With regard to smooth vs. rough drum tests, the Conti GP4Ks had a significant rank change compared to others. That's interesting, especially since I'm currently running it. Very curious as to how this reflects in the real world.
-- Dan

[cachagua]

Jobst Brandt was the man...

The man, and a well-dressed man, too.

[shovelhd]

I also like the Pro One's in 28's. Has anyone ever run them with latex tubes? I'm thinking of converting them for the travel bike.

[Mark McM]

Originally Posted by Rusty Luggs

I find it interesting that most of these articles do not seem to support the notion that lower pressure = lower rolling resistance, except on exceptionally rough road surfaces

There are two primary source of rolling resistance - hysteresis losses in the tire, and vibrational losses in rest of the system. Hysteresis losses in the tire always decreases with pressure; however these losses decreases asymptotically, so there is little extra gain at very high pressures. On the other hand, vibrational losses increase with pressure, almost proportional with pressure. Therefore, there exists a point where the decreases in hysteresis losses are more than offset by increases in vibrational losses, so the total losses will only increase with pressure. The pressure at which this inflection occurs is sometimes called the Breakpoint Pressure. The existence of the Breakpoint pressure is discussed in this article on Slowtwitch:

http://www.slowtwitch.com/Tech/What_...ube__1034.html

The Breakpoint Pressure will vary with the tire and the surface roughness, and will be lower on rough surfaces and higher on smooth surfaces.

In regard to the applicability of drum testing to the real world: Drum testing only tries to measure hysteresis losses in the tire itself, not the vibration losses in the rest of the system, which is why drum rolling resistance only decreases with pressure. However, it has been confirmed multiple times that although the magnitudes of rolling losses varies with surface roughness, the relative ranking of tire rolling resistance stays the same. In other words, if tire A has lower resistance than tire B on a smooth surface, then tire A will still have a lower resistance than tire B on a rough surface (even when adding in the vibrational losses). Therefore drum testing is useful for comparison purposes between tires.