Roller Data

Newly updated on 3/20/2010 !!! Al Morrison is back at it with his Crr data sets (just click on pdf links in the table after the jump)

Date	File name	revision #
11/29/2006	AFM_tire_testing.pdf	1
12/11/2006	AFM_tire_testing_rev2.pdf	2
12/18/2006	AFM_tire_testing_rev3.pdf	3
01/10/2007	AFM_tire_testing_rev4.pdf	4
05/21/2007	AFM_tire_testing_rev5.pdf	5
05/31/2007	AFM_tire_testing_rev6.pdf	6
05/11/2008	AFM tire testing rev7.pdf	7
11/18/2008	AFM tire testing rev8.pdf	8
03/20/2010	AFM_tire_testing_rev9.pdf	9

Users who would like to do custom sorting, or other data visualization can find an unformatted *.csv file here.

Additional reading/commentary on how these rolling resistance tests compare to the real world:

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email us today with your own links that we can incorporate on this page.

Al Morrison's Bumpy Roller Data sets

Date	File name	revision #
03/29/2007	AFM_Bumpy_Data_BTR_rev1.pdf	1

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Road Tubeless Tests
written by Steve Boehmke, February 23, 2010

Hi Guys,

Just ready the dealio about the new IRC Tubeless tires.

Noticed that your tests are done inflating the tires to 120psi.

Our Road Tubeless tires are recommended to be run at 100 pounds or less depending on rider weight. At 100 pounds, you will experience the true benefits of Road Tubeless, including a more comfortable ride, and faster rolling on most road surfaces.

It would be cool if you could re-test at the recommended numbers and see the advantages.

Thanks. Cool site.
gpeace,

SB (Marketing for Hutchinson Tires North America)

...
written by kraig, February 23, 2010

Hi Steve,

Thanks for stopping by! :-)

I'd recommend you mosy on over to the forum ( http://forum.biketechreview.com ) and see if you can sweet talk Al into giving your test suggestion a go.

FWIW, I'd be very surprised if the lower pressure did anything but made things worse from a Crr perspectve on the rollers. I've also found similar trends when it comes to lower pressures and on-road testing as well (as noted in a couple links above).

Fat Faster than Skinny
written by Dodger, April 09, 2010

It looks to me, based on the .csv file, that the 'fat' tires are faster than the 'skinny' tires - at least the same tire by the same manufacturer. This holds for 7 out of 10 clinchers (with two having no difference), and 4 out of 5 tubulars. Note that the difference is greater than the std dev.

Any idea at what point in a climb weight become more significant than Crr? Or in a jump? More to the point, my guess is that it makes sense to go with 25s instead of 23s or skinnier. Am I off-base with this conclusion?

...
written by kraig, April 09, 2010

Any idea at what point in a climb weight become more significant than Crr?

This question is a real can of worms!

It really depends on the specifics of the comparison you are wanting to make, and to generalize things would really be a disservice to you, I think. I think it would be tough to outperform (hey, keep in mind that bike racin' ain't a math problem, eh? smilies/wink.gif

) a clincher veloflex record 20mm during a hillclimb (well, at least the VF record I have tested on my own rollers). That sucker is light, low Crr, and narrower than 25mm.

Here's a quick and dirty example of how things might play out on a climb I have near where I live (quick 'n dirty spreadsheet I whipped up):

elevation gain220m
time 990seconds
dist6000m
vehicle mass84kg

delta mass0.45kg
delta crr0.0002
delta cxa0.0075m^2

power delta
mass1.0W
crr1.0W
aero1.0W

so, the balance point for this specific case is the "deltas" listed above.

Here's a link where you can play out all sorts of scenarios using whatever assumptions/data you'd like:

http://www.analyticcycling.com..._Page.html

Don't forget that "on road/real life" crr is not necessarily the same as what is listed on Al's chart - especially for the lower speed hillclimb situation you appear to be interested in.

Or in a jump?

You might find this article of interest when it comes to "jumps":

http://biketechreview.com/revi...erformance

More to the point, my guess is that it makes sense to go with 25s instead of 23s or skinnier. Am I off-base with this conclusion?

For hillclimb stuff, I reckon you've got the right "big picture" things to focus on...mass and crr. Aerodynamics of the tire play less of a role in this hillclimb type of effort than they might here:

http://biketechreview.com/aerodynamics/tires

...but tire aerodynamics can still play a role even on a net elevation gain type of effort. So, if your assumed crr is equal, I'd go with the narrower and lighter option.

Great questions, Dodger! Happy to address any follow-ups you might have