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New Crr roller data

 

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rruff

Feb 6, 13 9:29

Post #1 of 225 (12687 views)
New Crr roller data Quote | Reply

Finally got everything set up to test my tire collection. I originally put the rear wheel on a pair of rollers with the front wheel held fixed, but the results seemed to be sensitive to subtle position variations. So I went with one aluminum roller, and the data was more consistent. The protocol is similar to what Al Morrison and others have done. Equations are derived from Bicycling Science #3, by David Gordon Wilson.

I applied a 1.5x factor to try to get a ballpark number for resistance on a smooth road, but I suspect most of us will experience even higher drag. I'm not sure though if an X factor would be more appropriate or an offset. For comparison purposes, 1.5x is probably decent.

I'm planning to do some testing in hot and cold environments, because I'm curious about the temperature effect. Just from these tests I could tell that the tire resistance would drop substantially as the tire warmed up from 65 to ~90F.

After I was done, I thought the Maxxis Radiale might have been been unfairly penalized from being squashed on a single 3 inch diameter roller, so some day I'll try it with two rollers and maybe a higher pressure to see if there is a substantial difference. I know this tire sucks though based on my speed while riding it on the road. I wasn't something I could really "feel" but my speed data after the fact indicated that something weird was going on.

Which brings up another interesting point... you can't really tell what the rolling resistance of a tire is by fondling it, weighing it, or riding it... or judging by price or what the ads say.







Maxxis Radiale 22 Wow. Now I know why my rides were always so slow with these on. They have a smooth ride and corner nice though. Big tread lip transition… probably the least aero tire as well. And the most expensive. Very small casing.

Deda Tre HST 23 I was hoping for this one to do well. It's very light, supple, and smooth. But resistance is very high.

Vittoria Rubino Pro 23 A relatively inexpensive tire that has a nice ride, and would be suitable for training. Small tire though for a 23… might want to opt for the 25.

Schwalbe Ultremo ZX 23 The durability, tread life, and price of a full racing tire… but lacking the speed. Nice large round profile, light, and feels nice, though.

Michelin Pro4 Race SC 23 I was hoping that this tire would be at least as good as the GP4000. But it's slower, as well as being more puncture prone and shorter lived.

Continental GP4000S 23 A little more resistance than the best tires, but represents a big improvement in durability and longevity.

Continental GP Supersonic 20 Good fast TT tire if you are using narrow rims.

Vittoria Evo Corsa CX 23 Probably not very aero with the large round shape, tread pattern, and tread lip, but good Crr as expected.

Vittoria Evo Triathlon 22 If you like "open tubulars" this is a good one to go for. Nice smooth shape except for the lip where the glued-on tread meets the sidewall.

Continental Attack 22 Performed surprisingly well. Might be a better than average sample, since it is lighter than a newer one I have (which I'll test as soon as it's broken in). Construction is similar to the Supersonic, but this tire has an anti-puncture belt.

Continental GP Supersonic 23 Did very well, as expected. Smooth tire; should have good aerodynamics. No anti-puncture belt, and very thin tread, but are not as prone to puncture or damage as you might think.


BTW... any way to get the image to display full size?


(This post was edited by rruff on Feb 6, 13 9:42)


gibson00

Feb 6, 13 9:45

Post #2 of 225 (12650 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

No tubular love? :(


Ex-cyclist

Feb 6, 13 9:56

Post #3 of 225 (12627 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Nice! Thanks for doing this.

Holy crap I can't believe how bad the Maxxis is. 100w diff? Good training tire I guess.


Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
AeroCamp 2.0AeroCamp2.0 at A2 June 12-14


rroof

Feb 6, 13 9:58

Post #4 of 225 (12623 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Thanks Ron!

Would like to see a Veloflex Record tested ...
____________________________________
Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD


nightfend

Feb 6, 13 10:04

Post #5 of 225 (12601 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

The fast Michelin's are just now becoming available. They are the Pro 4 Comp and Pro 4 Comp Limited. I think those will test much faster. The Pro 4 Service Course is not the high end of the Pro 4 line.

BTW - I HATE the naming system Michelin uses as it is confusing: Pro 4 Endurance, Pro 4 Service Course, Pro 4 Comp Service Course, Pro 4 Comp Service Course Limited. Yeesh.


Nick_Barkley

Feb 6, 13 10:05

Post #6 of 225 (12598 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Thanks for the great work.

I would definitely like to see more info on the Conti Attack.


(This post was edited by Nick_Barkley on Feb 6, 13 10:16)


AndyF

Feb 6, 13 10:07

Post #7 of 225 (12595 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Nice work, Ron!

AndyF
http://alphamantis.com
#findyouraero


rruff

Feb 6, 13 10:08

Post #8 of 225 (12590 views)
Re: New Crr roller data [rroof] [In reply to] Quote | Reply

Would like to see a Veloflex Record tested ...

Al has tested that one a couple of times. It might be a hair faster than the Supersonic, but it seems to vary more... and it has poor aerodynamics.

To the other guys:

No tubulars from me. I have a Powertap with a clincher rim.

I've heard anecdotal comments that other Maxxis tires are slow, but I've never seen a test. I'd be curious to try one of their other race tires with more normal construction. Not curious enough to buy one though. Need to unload the Radiales I have... I can't stand to ride slow stuff even for training.



Jamaican

Feb 6, 13 10:09

Post #9 of 225 (12588 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

I scanned quickly but I didn't see any mention of latex tubes, or is that implied? Good stuff.


FS: Shoes, Stems, Brakes. Free Shipping In North America


Ex-cyclist

Feb 6, 13 10:15

Post #10 of 225 (12574 views)
Re: New Crr roller data [Jamaican] [In reply to] Quote | Reply

Jamaican wrote:
I scanned quickly but I didn't see any mention of latex tubes, or is that implied? Good stuff.

It is all on the chart. Vredestein Latex.


Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
AeroCamp 2.0AeroCamp2.0 at A2 June 12-14


Jamaican

Feb 6, 13 10:19

Post #11 of 225 (12556 views)
Re: New Crr roller data [Ex-cyclist] [In reply to] Quote | Reply

Ex-cyclist wrote:
Jamaican wrote:
I scanned quickly but I didn't see any mention of latex tubes, or is that implied? Good stuff.


It is all on the chart. Vredestein Latex.

Oops. Right under my nose. Thanks.


FS: Shoes, Stems, Brakes. Free Shipping In North America


Stalkan

Feb 6, 13 10:19

Post #12 of 225 (12553 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Would love to see the Bonty R4 aero. I am torn right now of whether to stick with it or try out my Attack.


RChung

Feb 6, 13 10:21

Post #13 of 225 (12548 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Very nice. Thanks.


Ex-cyclist

Feb 6, 13 10:23

Post #14 of 225 (12538 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Was this a double blind test? If it wasn't how can we trust the data?


Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
AeroCamp 2.0AeroCamp2.0 at A2 June 12-14


rruff

Feb 6, 13 10:24

Post #15 of 225 (12531 views)
Re: New Crr roller data [nightfend] [In reply to] Quote | Reply

The fast Michelin's are just now becoming available.

I'm sure they will be faster, but I doubt they will be too impressive. Looks like they are taking a basic racing tire (the one I tested) and then offering models with thinner tread and the anti-puncture layer removed. Conti does the same thing... but they have the advantage of a more durable and lower resistance tread compound. Based on anecdotal reports I'd guess the Pro4 SC's tread life is more on a par with the Attack/Force... which are significantly faster.



npage148

Feb 6, 13 10:28

Post #16 of 225 (12512 views)
Re: New Crr roller data [Ex-cyclist] [In reply to] Quote | Reply

I'd be more concerned about testing only 1 tire of each style. What is the tire to tire variability for each model?


Ex-cyclist

Feb 6, 13 10:30

Post #17 of 225 (12505 views)
Re: New Crr roller data [npage148] [In reply to] Quote | Reply

You don't do pink do you.....

Like I said in the other thread, use it or not it is up to you. He's not getting paid for this. That and the results are pretty consistent with what AFM has found.


Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
AeroCamp 2.0AeroCamp2.0 at A2 June 12-14


rruff

Feb 6, 13 10:42

Post #18 of 225 (12477 views)
Re: New Crr roller data [Stalkan] [In reply to] Quote | Reply

Would love to see the Bonty R4 aero.

Al has tested that one. http://www.biketechreview.com/...ire_testing_rev9.pdf

It does very well... and is purported to have very good aero properties of course. Don't know about the durability and puncture resistance. It appears to be based on the Vittoria Diamonte which isn't noted for durability, but it's likely as good as a Supersonic.

If you send me one of your tires I'll test it... a used one preferably (else I'll have to break it in for you), but not used up.

Speaking of Vittorias, they make a track tire based on the Diamonte with thinner tread and no anti-puncture belt. I thought about giving one of those a try... but then decided it was a little too extreme even for me, to actually use in a race.


(This post was edited by rruff on Feb 6, 13 10:44)


jjabr

Feb 6, 13 10:56

Post #19 of 225 (12440 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Great data, thanks! I'd be interested in the Zipp Tangentes. Are you accepting tire donations?


Tom A.

Feb 6, 13 11:00

Post #20 of 225 (12431 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

Good stuff Ron!

I started doing some roller testing myself about a year ago (http://www.wattagetraining.com/...ic.php?f=2&t=348), but I haven't collated everything into a single table yet like you have here...that's on my list of things to do since I've got a few tires I want to test soon.

A couple of comments/questions:

- Tell me more about the "position sensitivity" you say you observed with 2 rollers on the rear. I haven't noticed that...but I also make sure that the wheel is centered on the rollers by lifting the front end of the bike up and letting the rear find the center and then I carefully place the front end back down.

- I assume you're correcting for the differing tire rollouts, right? If not, you should do so. A handy tip for avoiding needing to do this is that I glued a magnet to the side of one of my rear rollers and then I read out the speed using a separate Garmin speed/cadence sensor taped to the roller frame. I set the head unit to the rollout of the roller and it reads the rear "road speed" then just fine. That saves a LOT of time and effort in trying to get the proper rollout for the rear wheel on the roller.

- You may want to look at this data I put together last year on the temp sensitivity: http://www.wattagetraining.com/...p;t=139&start=90
I seemed to be getting more like 1.4%/deg C from my measurements. If you look to earlier in that thread, you'll also see the data from where I took measurements from outdoor rides and found that tire temps basically followed ambient temps with a relatively fixed offset.

-On the heat up of the tires on the rollers...it's funny, one could almost use just the temp rise at a given speed as the measure of which tires are slower and faster. The slower tires tend to heat up a LOT more (more internal losses). Rollers really ARE some good "Crr amplifiers" ;-)

- My own limited regression testing indicates a 1.5X factor from AFM's data for typical "on road" Crr...I think Andy Coggan has come up with something more like 1.45, so I don't think that's an unreasonable assumption. The only way to try to correlate that for you and your setup would be to do a few regression-style field tests and see where the Y-intercept ends up.

Anyway...good stuff...and thanks for sharing!


http://bikeblather.blogspot.com/


rruff

Feb 6, 13 11:05

Post #21 of 225 (12417 views)
Re: New Crr roller data [npage148] [In reply to] Quote | Reply

I'd be more concerned about testing only 1 tire of each style. What is the tire to tire variability for each model?

I have another Attack being broken in currently, and 2 more on order. I also have another Supersonic 20mm and 23mm and GP4000S, that I can test next time.

I tested the SS 20mm four separate times and would guess a scatter ballpark of ~+-1%. Also note that I test all of these at least "broken in" so there is likely some resistance variation due to mileage as well.



rruff

Feb 6, 13 11:24

Post #22 of 225 (12374 views)
Re: New Crr roller data [jjabr] [In reply to] Quote | Reply

I'd be interested in the Zipp Tangentes. Are you accepting tire donations?

Aren't the Tangentes old generation Vittoria Corsas? I wouldn't expect any surprises there. As I recall Zipp even recommended the GP4000S as being faster on their new rims.

I guess I will take donations for tires that interest me, but unlike Al (who is most generous!) I'd like you to pay for return shipping if want the tire back. Also, I want the tires at least broken in... but not *too* used. Most (but not all!) tires come with seams and sometimes a surface coating that IMO needs to get worn off before the tire is ready to race. The tires seem to get more supple with some miles also. So if you send me a new tire I'll assume you want me to break it in. And if it gets destroyed...





3Aims

Feb 6, 13 11:29

Post #23 of 225 (12359 views)
Re: New Crr roller data [rruff] [In reply to] Quote | Reply

What jumps out to me is for a HIM or IM why someone would choose anything other than the Attack. It has almost the best Crr, the thickest thread, a puncture belt, and is also fairly aero.

I always race with the Corsa Evo tires and they cut like mad and have poor aero properties. Their Crr is almost a wash to the Attack, but they can flat much easier.


rruff

Feb 6, 13 11:53

Post #24 of 225 (12316 views)
Re: New Crr roller data [Tom A.] [In reply to] Quote | Reply

I started doing some roller testing myself about a year ago (http://www.wattagetraining.com/...ic.php?f=2&t=348), but I haven't collated everything into a single table yet like you have here...that's on my list of things to do since I've got a few tires I want to test soon.

That's great Tom... the more the merrier!

Tell me more about the "position sensitivity" you say you observed with 2 rollers on the rear. I haven't noticed that...but I also make sure that the wheel is centered on the rollers by lifting the front end of the bike up and letting the rear find the center and then I carefully place the front end back down.

I spent a few hours running all the tests and then went back and did some of the earlier ones over, and there was an appreciable difference (lower the 2nd time). I was looking over some ancient posts about this stuff and noticed that Jens Heycke mentioned he got variations if wheel's position shifted. I didn't spend any time trying to isolate the cause, but guessed that a position change on the rollers *might* have been it. I figured just using one roller would make it simpler, and I got consistent results that way. Then all I have to do check that the wheel is properly position over the roller with a plumb. But it is certainly possible that two rollers are fine if you are careful with positioning. I really hope my latest protocol is ok, because I don't want to retest all of these again...

I assume you're correcting for the differing tire rollouts, right?

Yes, it's a guess though based on the tire height.


Thanks for your thoughts!




zamm0

Feb 6, 13 12:00

Post #25 of 225 (12298 views)
Re: New Crr roller data [3Aims] [In reply to] Quote | Reply

3Aims wrote:
What jumps out to me is for a HIM or IM why someone would choose anything other than the Attack. It has almost the best Crr, the thickest thread, a puncture belt, and is also fairly aero.

I always race with the Corsa Evo tires and they cut like mad and have poor aero properties. Their Crr is almost a wash to the Attack, but they can flat much easier.
I've found very good reliabiity with the evo cx on the back. I think the Attack is front wheel specific whereas its counterpart the Force is designed for the rear. Would like to see the latter tested.

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Ironman prize money
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