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New Crr roller data
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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?
Last edited by: rruff: Feb 6, 13 9:42
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Re: New Crr roller data [rruff] [ In reply to ]
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No tubular love? :(
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Re: New Crr roller data [rruff] [ In reply to ]
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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
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Re: New Crr roller data [rruff] [ In reply to ]
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Thanks Ron!

Would like to see a Veloflex Record tested ...

____________________________________
Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD
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Re: New Crr roller data [rruff] [ In reply to ]
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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.
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Re: New Crr roller data [rruff] [ In reply to ]
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Thanks for the great work.

I would definitely like to see more info on the Conti Attack.
Last edited by: Nick_Barkley: Feb 6, 13 10:16
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Re: New Crr roller data [rruff] [ In reply to ]
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Nice work, Ron!

AndyF
bike geek
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Re: New Crr roller data [rroof] [ In reply to ]
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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.

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Re: New Crr roller data [rruff] [ In reply to ]
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I scanned quickly but I didn't see any mention of latex tubes, or is that implied? Good stuff.


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Re: New Crr roller data [Jamaican] [ In reply to ]
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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
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Re: New Crr roller data [Ex-cyclist] [ In reply to ]
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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.


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Re: New Crr roller data [rruff] [ In reply to ]
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Would love to see the Bonty R4 aero. I am torn right now of whether to stick with it or try out my Attack.

My YouTubes

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Re: New Crr roller data [rruff] [ In reply to ]
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Very nice. Thanks.
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Re: New Crr roller data [rruff] [ In reply to ]
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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
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Re: New Crr roller data [nightfend] [ In reply to ]
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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.

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Re: New Crr roller data [Ex-cyclist] [ In reply to ]
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I'd be more concerned about testing only 1 tire of each style. What is the tire to tire variability for each model?
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Re: New Crr roller data [npage148] [ In reply to ]
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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
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Re: New Crr roller data [Stalkan] [ In reply to ]
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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.
Last edited by: rruff: Feb 6, 13 10:44
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Re: New Crr roller data [rruff] [ In reply to ]
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Great data, thanks! I'd be interested in the Zipp Tangentes. Are you accepting tire donations?
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Re: New Crr roller data [rruff] [ In reply to ]
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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/
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Re: New Crr roller data [npage148] [ In reply to ]
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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.

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Re: New Crr roller data [jjabr] [ In reply to ]
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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...



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Re: New Crr roller data [rruff] [ In reply to ]
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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.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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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!


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Re: New Crr roller data [3Aims] [ In reply to ]
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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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Re: New Crr roller data [3Aims] [ In reply to ]
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The Attack I tested was a few years old and very light. I remember when I got it the tread seemed as thin as the SS. It also is very well broken in, but still looks fine. The new one is heavier (185g when new), and the tread seems a little thicker. I expect its Crr to be about half way between the SS and GP4k on average.
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
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.
The Comps use a completely different casing based on their tubulars. Honestly they are a completely different tire with just a similar name. But, that's Michelin's fault.

Cool chart. Thanks for doing the testing. Nice to finally see proof that the Conti Attack is a fast tire.
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Re: New Crr roller data [rruff] [ In reply to ]
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Awesome. Great to see the Vittoria EVO CX's hanging in there - my tires, for, well, for a very long time!

I hear some rumblings that 25 is the new 23!


Steve Fleck @stevefleck | Blog
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Re: New Crr roller data [Fleck] [ In reply to ]
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After riding a Vittoria EVO CX tubular in 25, it really makes me sad riding a 22mm Conti on race day!

/kj

http://kjmcawesome.tumblr.com/
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Re: New Crr roller data [nightfend] [ In reply to ]
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Sorry... you are correct, the Comps have a 150tpi casing. Should be worth a look.
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Re: New Crr roller data [rruff] [ In reply to ]
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Wow, great stuff.

FWIW this seems to substantiate my seat of the pants roller work running the Pro 4 SC against a set of Corsa EVO CX II tubulars (both with latex tubes) the Corsa always seems to be at least one cog 'faster'. -they are mounted on a much faster set of wheels, but looks like it is not all aerodymanics.

This is your life, and it's ending one minute at a time. - Fight Club
Industry Brat.
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Re: New Crr roller data [Fleck] [ In reply to ]
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I agree. I can't seem to get away from the Corsa Evo tire when it comes to racing. I just love the way they feel and handle.
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Re: New Crr roller data [3Aims] [ In reply to ]
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I can't seem to get away from the Corsa Evo tire when it comes to racing

Racing?

I ride them all the time!

Every ride, a thing of beauty.

Why ruin a great ride with cheap rubber?

The knock on the Vittoria EVO CX historically has been that it's not that durable and does not last that long. We ride on shitty roads, and I don't seem to get an unusual number of flats ( on average 1 - 3/year) and for the riding I do - a moderate amount - they last a full season of outdoor riding. That's fine for me.

The Conti GP 4000s is the one that intrigues me. It's close to the Vittoria's in rolling resistance, but reports seem to say it's more durable and lasts longer. Maybe I'll change things up this year and go with a set of bad-ass
Conti GP 4000s 25's! :)



Steve Fleck @stevefleck | Blog
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Re: New Crr roller data [Fleck] [ In reply to ]
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The Evo's seem to flat on me when I use them for training and they get beyond 500-750 miles.

I train on the GP4000s and I hate them. Hate the way they feel. Hate the way their corner. Dead, IMO. However, they last a long time (more than the Evo's).

When I put new Evo's back on my wheels last weekend for Panama 70.3 it felt like my bike came to life again. Now that I am in training mode again until Wildflower, I put the GP4000s back on and the dead feeling is back for a few months.
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Re: New Crr roller data [Fleck] [ In reply to ]
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Fleck wrote:
I can't seem to get away from the Corsa Evo tire when it comes to racing

Racing?

I ride them all the time!

Every ride, a thing of beauty.

Why ruin a great ride with cheap rubber?

The knock on the Vittoria EVO CX historically has been that it's not that durable and does not last that long. We ride on shitty roads, and I don't seem to get an unusual number of flats ( on average 1 - 3/year) and for the riding I do - a moderate amount - they last a full season of outdoor riding. That's fine for me.

The Conti GP 4000s is the one that intrigues me. It's close to the Vittoria's in rolling resistance, but reports seem to say it's more durable and lasts longer. Maybe I'll change things up this year and go with a set of bad-ass
Conti GP 4000s 25's! :)

Take a look at the Vittoria EVO Corsa SL instead of the CX if you're considering the GP4000s. The tread compound is different than the CX (feels more like what was used on the Bontrager and Specialized "open tubular" models which were smokin' fast tires and had great durability and grip IME) and there's no "herringbone" tread pattern (it's slick, thus the "SL" moniker). I've found them to be fairly durable AND they handle better than the CXs IMHO. I've always found the CXs to handle a bit "wobbly" and the tread compound seems too soft and easily cut.

I haven't thrown one on the rollers yet (possibly this weekend), but I don't expect it to test "slow" either... ;-)

http://bikeblather.blogspot.com/
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Re: New Crr roller data [3Aims] [ In reply to ]
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3Aims wrote:
The Evo's seem to flat on me when I use them for training and they get beyond 500-750 miles.

I train on the GP4000s and I hate them. Hate the way they feel. Hate the way their corner. Dead, IMO. However, they last a long time (more than the Evo's).

When I put new Evo's back on my wheels last weekend for Panama 70.3 it felt like my bike came to life again. Now that I am in training mode again until Wildflower, I put the GP4000s back on and the dead feeling is back for a few months.

To minimize that "dead" feel with the Contis, run latex tubes inside them. It might sound silly, but there is a noticeable "feel" difference when you do so. Even with latex tubes however, they never feel as good as a REALLY fast tire with latex tubes in them :-)

http://bikeblather.blogspot.com/
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Re: New Crr roller data [rruff] [ In reply to ]
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Take a look at the Vittoria EVO Corsa SL instead of the CX if you're considering the GP4000s. The tread compound is different than the CX (feels more like what was used on the Bontrager and Specialized "open tubular" models which were smokin' fast tires and had great durability and grip IME) and there's no "herringbone" tread pattern (it's slick, thus the "SL" moniker). I've found them to be fairly durable AND they handle better than the CXs IMHO. I've always found the CXs to handle a bit "wobbly" and the tread compound seems too soft and easily cut.

Tom,

Good and trustworthy advice as always.

So why are the CX the ones you see in the stores. In our parts, the only high performance clinchers that you see with decent availability, are the Vottoria EVO CX's, The Michelin ProRace's and the high-end Continentals. It's extremely rare to see any other tires at retail.

Now, I'll admit this is a bit of a red-herring, because tires are not an every-day purchase. As noted I tend to change them up ounce a season.





Steve Fleck @stevefleck | Blog
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Re: New Crr roller data [Fleck] [ In reply to ]
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I don't know but I'm not too happy with the grip on the CX either, and that tread pattern does not make sense to me. I would be willing to try the SL and *expect* it to be better.

Fleck wrote:
Take a look at the Vittoria EVO Corsa SL instead of the CX if you're considering the GP4000s. The tread compound is different than the CX (feels more like what was used on the Bontrager and Specialized "open tubular" models which were smokin' fast tires and had great durability and grip IME) and there's no "herringbone" tread pattern (it's slick, thus the "SL" moniker). I've found them to be fairly durable AND they handle better than the CXs IMHO. I've always found the CXs to handle a bit "wobbly" and the tread compound seems too soft and easily cut.

Tom,

Good and trustworthy advice as always.

So why are the CX the ones you see in the stores. In our parts, the only high performance clinchers that you see with decent availability, are the Vottoria EVO CX's, The Michelin ProRace's and the high-end Continentals. It's extremely rare to see any other tires at retail.

Now, I'll admit this is a bit of a red-herring, because tires are not an every-day purchase. As noted I tend to change them up ounce a season.





Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: New Crr roller data [rruff] [ In reply to ]
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Thanks for doing this.

Would love to see this done again, but on a "wide" rim that more directly reflects the shape of current aero wheels, and see to what impact a wide rim with the corresponding change in the tire shape has on the Crr.

Matthew
Twitter: @AlphaDogCycling
Instagram: @AlphaDogCycling
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Re: New Crr roller data [Fleck] [ In reply to ]
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Fleck wrote:
Take a look at the Vittoria EVO Corsa SL instead of the CX if you're considering the GP4000s. The tread compound is different than the CX (feels more like what was used on the Bontrager and Specialized "open tubular" models which were smokin' fast tires and had great durability and grip IME) and there's no "herringbone" tread pattern (it's slick, thus the "SL" moniker). I've found them to be fairly durable AND they handle better than the CXs IMHO. I've always found the CXs to handle a bit "wobbly" and the tread compound seems too soft and easily cut.

Tom,

Good and trustworthy advice as always.

So why are the CX the ones you see in the stores. In our parts, the only high performance clinchers that you see with decent availability, are the Vottoria EVO CX's, The Michelin ProRace's and the high-end Continentals. It's extremely rare to see any other tires at retail.

Now, I'll admit this is a bit of a red-herring, because tires are not an every-day purchase. As noted I tend to change them up ounce a season.



That's a good question. About all I can speculate is that tire has just been around for SO long, it's what most everyone thinks of when they hear "Vittoria"...so that's what gets stocked.

Anyway, like I said, the Corsa SL reminds me (in look and feel) a LOT of the Bontrager "open tubular" tire that was made by Vittoria for them. Those were my FAVORITE road race tire. My suspicion is that after making those tire for Bontrager, Vittoria might have learned a thing or 2. The "SL" model come out suspiciously not long after the Bonty tire was discontinued, IIRC...

I also have one of the EVO Triathlon models Ron tested above. It's very similar to the SL, but slightly narrower at 22C (mine actually measures at 21.5mm, just like Ron's did) and I think would be an excellent front tire choice to mate with wide-rimmed aero wheels. Also, the cool thing about the clincher version of the EVO Triathlon is that you can run latex tubes inside. The tubular version comes with a butyl tube...ostensibly to minimize air pressure reduction when leaving your bike racked overnight or something :-\

http://bikeblather.blogspot.com/
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Re: New Crr roller data [alphadogcycling] [ In reply to ]
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alphadogcycling wrote:
Thanks for doing this.

Would love to see this done again, but on a "wide" rim that more directly reflects the shape of current aero wheels, and see to what impact a wide rim with the corresponding change in the tire shape has on the Crr.

AFM already did that years ago, and there is no measurable difference.

I repeated that to my own satisfaction last year.

http://bikeblather.blogspot.com/
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Tom, agree on the Mondo "open tubular"...wish they still made them. Can't seem to find the Corsa SL in a clincher though...


Coach at KonaCoach Multisport
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Re: New Crr roller data [Terra-Man] [ In reply to ]
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Terra-Man wrote:
Tom, agree on the Mondo "open tubular"...wish they still made them. Can't seem to find the Corsa SL in a clincher though...

I got a couple during a sale on "The Clymb" not long ago.

You might need to special order them through your LBS. I did a search last weekend for the tubular version of the SL, and IIRC Wiggle had them online...don't know about the clincher though. Check Amazon?

Just looked...yeah, Wiggle lists them, but they're out of stock until April apparently... http://www.wiggle.co.uk/...-clincher-road-tyre/

http://bikeblather.blogspot.com/
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Re: New Crr roller data [rruff] [ In reply to ]
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Wow, great thanks for doing this!
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Re: New Crr roller data [rruff] [ In reply to ]
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With regards to the Conti Attack, I thought those came in a set with the Force for a rear tire. Does the force run similar or slower? And if so how much? Enough to make running the set not worth it over some other choices? Or is this potentially advocating running the attack on front and rear wheel?
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Re: New Crr roller data [3Aims] [ In reply to ]
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3Aims wrote:
I train on the GP4000s and I hate them. Hate the way they feel. Hate the way their corner. Dead, IMO. However, they last a long time.

I've trained on them for years as well and based on feel am always surprised on how low the Crr is cuz it doesn't seem that way. They square off in the rear worse than any tire I've ever used and they don't inspire confidence in cornering.

My latest training tires are Schwalbe Durano's and I definitely prefer those over the G4K's. My favorite tire overall is still the Veloflex Corsa 22.
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Re: New Crr roller data [jackmott] [ In reply to ]
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jackmott wrote:
I am very enamored of the attack!

Yeah, well me too. I've been thinking about making the switch to an attack on the front since my beloved Record is getting pretty thin (even new at 350 tpi, they are REALLY thin). So, just pulled the trigger on some.

____________________________________
Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD
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Re: New Crr roller data [rruff] [ In reply to ]
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Ron,
You noted that you normalized the results to a temp of 75F, but I don't see where you noted the ambient temp in the chart. You didn't normalize using the tire temp, did you?

http://bikeblather.blogspot.com/
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Re: New Crr roller data [rruff] [ In reply to ]
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This is awesome, thanks for your efforts!

I was very surprised with the Attack. Would be curious to see how a new tire does.

I would like to extend a very generous offer to those guys in my AG that always beat me: In recognition of your superior talent, I would like to buy you a set of Maxxis Radiales for your race wheels. Consider it a token of my respect!

In other things...

Personally, I had a bad experience with the Conti SS. I know it may just be bad luck, but I flatted in a race in which I would have likely podiumed, and subsequently had to toss them after 200 miles. I know some people complain about the reliability of Vittoria Evos, but they seem way more robust than the SS.

Re some of the other comments in this thread, maybe I have a tone-deaf butt, but I have never been able to discern any different feel between latex tubes and butyl. Nonetheless, I use latex for racing because I trust the data more than I trust my butt.
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Re: New Crr roller data [Zoom_zoom_Ben] [ In reply to ]
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With regards to the Conti Attack, I thought those came in a set with the Force for a rear tire. Does the force run similar or slower?

I previously bought two Attacks individually, but now the twin packs of Force/Comp are considerably cheaper than either one alone. I don't know if the Force has anything different in terms of tread compound and thickness. If not, it should have a bit lower rolling resistance than the Attack. I'll have one to test next time. For racing I think I'd use the Attack front and rear even with a wide rim. My main road wheels are 23mm and it makes a nice profile on those. You could always use the Force for training.

Nice price here: http://www.probikekit.com/...-tyre-twin-pack.html


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Re: New Crr roller data [rruff] [ In reply to ]
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Does anyone run Hutchinsons? I like the Fusions for training and have run the Atoms for a few races. The Atoms are very light and narrow. I am sure they offer little flat protection so I use them for sprints and oly's only. You can get them for almost nothing at Performance most of the time. Both the Fusions and the Atoms have a decent road feel to me when run with latex tubes (not as good as Corsas but about the same as Pro3s)
Am I the only one that likes them? Can't find much Crr data on them.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Tom, thoughts on the following:

http://www.artscyclery.com/...age-VTOCESCTS23.html

This wouldnt happen to be the same as the SL would it?

Just a week ago, based on some perusing of the forum, I decided to go with the attack/force combo on my race wheels this year. Nice to see the attack validated by Rons work.

"One Line Robert"
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Re: New Crr roller data [wsrobert] [ In reply to ]
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wsrobert wrote:
Tom, thoughts on the following:

http://www.artscyclery.com/...age-VTOCESCTS23.html

This wouldnt happen to be the same as the SL would it?

Just a week ago, based on some perusing of the forum, I decided to go with the attack/force combo on my race wheels this year. Nice to see the attack validated by Rons work.

Yup. That's the SL.

http://bikeblather.blogspot.com/
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Re: New Crr roller data [stevemurf1] [ In reply to ]
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Does anyone run Hutchinsons?

Tour's tests on the ones that take tubes (Top Speed, Intensive, Fusion) show an awful Crr. The tubeless are much better... but the tubeless Fusion is still worse than the GP4k with a latex tube. I've never seen a test of the Atom, but if you are running them tubeless they are probably not bad.

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Re: New Crr roller data [rruff] [ In reply to ]
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I'd be interested to see what I think could quite possibly be the worst CRR 23mm pneumatic tire tested ever: Continental Super Sport Plus . Why? I ride with these pieces of shit feeling, terribly slow tires all winter in order to avoid flats when it is in the 20s, no chance in hell I'm stopping if I do either. (Thankfully these are stiff enough I can probably ride them without air) Anyways it would be awesome to quantify just how slow these are. I have a tire I would be willing to send you to test, probably 150 miles on it.

---------------------
Jordan Oroshiba --- Roadie invading Triathlete space for knowledge access
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff,

I'm sure it is somewhere... but does the gains you give on smooth roads as indication are for one wheel or for one bike ? A difference in Crr of .0005 or 0,17mph is quite big so if it's only for one wheel then it is a lot for the two wheels.
Something else interesting in your chart : the height of the GP4000S, 49mm, quite higher than the others (the corsa CX is slightly wider but not as high), it probably tells a lot about why it's so aero (elliptical shape with a high height to width ratio).

Thanks for this great work !
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
BTW... any way to get the image to display full size?

Looks like it was resized to 650px Ron, cropping the empty rows and rotating to portrait orientation might make it more legible.
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Re: New Crr roller data [rruff] [ In reply to ]
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thanks for this. i'd love to do some testing and offer up some comparison data -- i have access to many tubulars.

are you basically just looking at average speed while holding a (relatively) constant power?

i see you have a "power" column--is that the power you were holding? how consistent do you strive to be? for what duration?

or are you aiming to ~35mph and trying to hold speed constant?

my head unit only displays speed to the nearest 0.1kph -- but perhaps if one rides a set distance (or time) then a more precise speed could be calculated.

any tips for someone looking to contribute useful data that may still be valid for comparison's sake?

i have a trainer and rollers available to use.
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Re: New Crr roller data [rruff] [ In reply to ]
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Could you outline the protocol a bit? It sounds like it isn't the most complicated thing in the world to do. I for one have aluminum rollers and would test and post up data if I could, and am sure a number of other slowtwitchers would as well.

You said it is similar to Al Morrison's protocol but I did some searching for that and failed.

---------------------
Jordan Oroshiba --- Roadie invading Triathlete space for knowledge access
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Re: New Crr roller data [pyf] [ In reply to ]
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I'm sure it is somewhere... but does the gains you give on smooth roads as indication are for one wheel or for one bike ?

Both wheels. Assuming that you are riding a TT bike with a half decent position. It doesn't change that much with weight or speed over a reasonable range.

But I highly recommend you set up a calculator with your personal parameters to see for yourself. That number is intended only to show a ballpark value. Yes, it isn't small. Remember the Jack Watts story about the guy who suddenly got dropped in crits because he mounted Gatorskins. The wrong (or right) tires can have a bigger effect than thousands of $ spent on the best aero equipment.

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Re: New Crr roller data [tetonrider] [ In reply to ]
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are you basically just looking at average speed while holding a (relatively) constant power?

I try to keep the speed fairly steady, and look to see if the power appears stable. Initially it will drop as the tire warms up. Then I ride a bit more, and average the last few minutes of output.

my head unit only displays speed to the nearest 0.1kph -- but perhaps if one rides a set distance (or time) then a more precise speed could be calculated.

0.1 kph is plenty good. My Powertap only reads in whole watts, so that is a much less precise measurement.

any tips for someone looking to contribute useful data that may still be valid for comparison's sake?

Tom put up a spreadsheet many years ago for doing roller calculations. Mine's a little different, but I'm sure we can figure it out if you have the rollers and the motivation for tedious testing.
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Re: New Crr roller data [joroshiba] [ In reply to ]
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Look for AFM on BikeTechReview.

I'll outline the procedure when I get a chance.
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Re: New Crr roller data [rruff] [ In reply to ]
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Okay, I have a 2010 Zipp 808, dimpled not Firecrest front wheel. I've been running the Continental 20mm SS for my race tire in combination with the Michelin latex tube. Considering aerodynamics would I be better off using the Supersonic 23mm?
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Re: New Crr roller data [rruff] [ In reply to ]
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This is great information. Thanks for putting this together and sharing this.

Since the Attack is only sold as a set with the Force (at least from what I've found), do you have the Force to test so it's possible to see the total difference of Crr?


Fraser Bicycle | First Endurance

Check out my blog here | Twitter:@tmalis3
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Re: New Crr roller data [Juanmoretime] [ In reply to ]
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Similar here. I have a Flashpoint 80 rim. My guess is that the better aerodynamics of the 20mm tire more than makes up for its higher Crr... in most conditions anyway.
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Re: New Crr roller data [Tom Maliszewski] [ In reply to ]
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I bought the Attacks separately, but will have a Force for next time. I suspect that the Force will be a little fat for optimal aerodynamics... with most rims anyway.
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
are you basically just looking at average speed while holding a (relatively) constant power?

I try to keep the speed fairly steady, and look to see if the power appears stable. Initially it will drop as the tire warms up. Then I ride a bit more, and average the last few minutes of output.


I've found that concentrating on a set cadence value is easier than speed. For my testing, I'll run the setup at 95rpm in a 53x13 for at least 5 min. to adequately warm up the tire, and then I'll do a 4 min. span at 90 rpm. I then take the average power and average speed from the final 2 minutes of the interval. Oh yeah...using km/hr instead of mph for the speed values typically gives better resolution.


rruff wrote:
my head unit only displays speed to the nearest 0.1kph -- but perhaps if one rides a set distance (or time) then a more precise speed could be calculated.


0.1 kph is plenty good. My Powertap only reads in whole watts, so that is a much less precise measurement.

That brings up a good point. Getting the "ground speed" measurement accurate is VERY important in the Crr measurement since it's DIRECTLY proportional to the Crr calculated. That's the main reason why I mounted a magnet to one of the rollers and mounted a separate ANT+ speed sensor. That way I know, with the least amount of error, what the "ground speed" is during the test and I don't have to change it from tire to tire. IME, trying to measure the rollout, or even estimate it, is fraught with difficulty and error possibilites, especially since you need to know the rollout ON the roller (which is different than it would be on a flat surface).

As an aside to those who have been following along in this, I'm pretty sure that Ron may not be applying his temp compensation to the Crr values correctly. He applied it to the temp rise of the tires above ambient, while I'm fairly certain that (i.e. the differences in energy dissipation between roller and flat) is already taken care of in the "roller to flat" calculations. Therefore, the temp compensation only needs to be applied using the difference of the test ambient temp to whatever reference temp he wants to normalize the Crr values to...we've been swapping PMs in an attempt to get that worked out. I'm just mentioning this since it most likely means that the absolute values, spread, and possibly even the ranking order of the Crrs in his original chart might change a bit...

http://bikeblather.blogspot.com/
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Re: New Crr roller data [Tom A.] [ In reply to ]
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The way I'm compensating for temperature changes is way better than not doing it at all...

And regarding the speed. I'm using the tire dimensions and guessing on the amount of compression. It wouldn't be unreasonable to have a relative error +- 1mm in the radius measurement, which would manifest as a +-0.3% error in the speed. IMO that isn't enough to be concerned about... considering that I'd need to buy a speed sensor to measure the roller. At any rate I'll refine the tire compression factor when I can get my wife to take measurements while I'm sitting on the bike.
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Re: New Crr roller data [tetonrider] [ In reply to ]
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Heres a good trick: Measure the diameter of your wheels, but set the value of your power meter to the smallest possible diameter. This will give you a too high speed, therefore reduces the procentual error. Transfer the data to your computer and calculate the actual speed with actualSpeed=measuredSpeed* setDiameter/actualDiameter
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
The way I'm compensating for temperature changes is way better than not doing it at all... .

Actually...I've got data (admittedly limited) that implies it may be worse than doing nothing. See my PM ;-)


rruff wrote:
And regarding the speed. I'm using the tire dimensions and guessing on the amount of compression. It wouldn't be unreasonable to have a relative error +- 1mm in the radius measurement, which would manifest as a +-0.3% error in the speed. IMO that isn't enough to be concerned about... considering that I'd need to buy a speed sensor to measure the roller. At any rate I'll refine the tire compression factor when I can get my wife to take measurements while I'm sitting on the bike.

I bet if you say "Honey, either I can buy this $40 speed sensor...or, every time I want to do this silly thing of testing tires I'm going to bug you to come over here and measure the distance from the axle of my bike to the roller...while I'm sitting on it...and oh yeah, you're going to have to consistently make that measurement to within +/-1mm, EVERY TIME. What do you want to do?" , she'll say: "Buy the sensor." ;-)

Seriously, that $40 is going to save you a LOT of time and hassle, and make your results more consistent to boot.

http://bikeblather.blogspot.com/
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Re: New Crr roller data [IJ] [ In reply to ]
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IJ wrote:
Heres a good trick: Measure the diameter of your wheels, but set the value of your power meter to the smallest possible diameter. This will give you a too high speed, therefore reduces the procentual error. Transfer the data to your computer and calculate the actual speed with actualSpeed=measuredSpeed* setDiameter/actualDiameter

I like that...it ties in well with my method of taking the "ground speed" off of the roller itself, which is a much smaller diameter and thus you also get more "triggers" per given unit of time :-)

http://bikeblather.blogspot.com/
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Re: New Crr roller data [rruff] [ In reply to ]
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The used R4 Aero is getting tossed in the post today but I have a feeling it is slightly different than the new model. Bontrager has changed the part number; however, other than the graphics I am not sure what has changed. I don't plan on mounting it up until next month so I won't be able to compare until then.

My YouTubes

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Re: New Crr roller data [rruff] [ In reply to ]
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The Michelin Pro4 Comp seems interesting too! See the article below:

http://www.bikeradar.com/...ew-pro4-tires-36376/
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Re: New Crr roller data [rruff] [ In reply to ]
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I had Al test a Maxxis a few years ago, along with some Challenge Criteriums that did great. The Maxxis (it was their top of the line racing tire, forget the name) did terribly.
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Re: New Crr roller data [rruff] [ In reply to ]
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I added my own data to "the mix":
http://bikeblather.blogspot.com/...ollers-chartand.html

The math behind the process is detailed here:
http://bikeblather.blogspot.com/...on-rollers-math.html

And, my spreadsheet is located here:
https://docs.google.com/...a3M/edit?usp=sharing

Enjoy! :-)

http://bikeblather.blogspot.com/
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Very nice!!! Love my Vittoria's even more now.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Wow, thanks for doing this!

That's gotta make you feel pretty good about your narrow Jet 90 with the Conti SS20 that was in the Mavic Wind Tunnel Challenge. Those Mavic Powerlink tires are slooooowwwww.
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Re: New Crr roller data [dmorris] [ In reply to ]
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dmorris wrote:
Wow, thanks for doing this!

That's gotta make you feel pretty good about your narrow Jet 90 with the Conti SS20 that was in the Mavic Wind Tunnel Challenge. Those Mavic Powerlink tires are slooooowwwww.

Yeah...not as bad...but it also has me thinking about which wheelset was the TRUE winner of that "shootout" ;-)

http://bikeblather.blogspot.com/
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Re: New Crr roller data [rruff] [ In reply to ]
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I'm not going to race on a Gator Skin, but I would be interested to know what kind of a number a training tire like has just as a point of reference.
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Re: New Crr roller data [J_R] [ In reply to ]
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J_R wrote:
I'm not going to race on a Gator Skin, but I would be interested to know what kind of a number a training tire like has just as a point of reference.

I think AFM has tested those and they're on his list. BTW, for the better performing tires we've both tested, if I put the "smooth to rough" factor at 1X in my spreadsheet to match how Al's numbers are calculated, then our results actually match up fairly well (i.e. within +/-.0001). It's on the slower rolling tires that we digress, with his measurements showing them to be slightly better than mine. My suspicion is that this is mostly likely due to the material differences of our rollers, with mine being aluminum and his being plastic. I think the slower rolling tires heat up more on his rollers and the higher temps give them a slight "advantage" in that setup.

Here's a handy hint I've developed after doing a bunch of this: If a tire has anywhere on it any sort of wording like "iron cloak", or "hardcase", or "gatorskin", or is touted for it's ability to not flat often...that's a pretty good clue it's not going to roll very well.

It's funny...in the hand, that Kenda Kaliente doesn't feel like it would be so bad of a tire. The casing is relatively thin and actually feels fairly flexible. But it is VERY slow. Of course, one of the features touted for it is a "bead to bead" layer of a kevlar woven belt...the "Iron Cloak" puncture prevention layer! Unfortunately, that's NOT a feature that will result in a low Crr tire.

http://bikeblather.blogspot.com/
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Thanks for taking the time to put that together Tom... great stuff!

I'm surprised at how poorly the new Challenge Criterium did... and the Tangente. Are these clinchers?

The Vittoria Tri is definitely a good tire. It just looks good and is fast too. I think I'll be sticking with the Supersonics, though.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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It's funny...in the hand, that Kenda Kaliente doesn't feel like it would be so bad of a tire. The casing is relatively thin and actually feels fairly flexible.

I wonder if Kenda makes the Deda HST also. I thought it would be fast based on how it felt and how light it was. But it really sucked. One thing that was evident after I changed it was how noisy it is when out of the saddle. The crummy Attack I have on now is very quiet by comparison.

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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
Thanks for taking the time to put that together Tom... great stuff!

I'm surprised at how poorly the new Challenge Criterium did... and the Tangente. Are these clinchers?

The Criterium was new out of the box. I've got that as my front tire on my road bike now so I'll probably retest it after a few hundred miles. Don't forget that the Tangente is a 21C model. I've never thought the Tangentes ever "felt" very good on the road even...they're sort of "dead" as compared to other tires with the same casing IME. And yes, they're both clinchers. I put the word "tubular" in the name of any of the tires listed that are tubies.

You'll also probably notice that there are 2 entries for the Challenge Forte tubular. The slower of the 2 was the one I glued up in "stages" last year to see "how much glue was enough", and the faster one was a freshly glued one. It's actually on the Mavic CXR wheel now...I pulled the Yksion off after running riding them twice and then doing the roller test...

rruff wrote:
The Vittoria Tri is definitely a good tire. It just looks good and is fast too. I think I'll be sticking with the Supersonics, though.

I keep thinking how well that tire would work on something like the Bontrager Aeolus 9, or a Firecrest 808...especially considering it's "shape" can't be any worse than the R3 tire shown in this Bontrager plot (and it most likely has a MUCH better Crr):



http://bikeblather.blogspot.com/
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Tom A. wrote:
Yeah...not as bad...but it also has me thinking about which wheelset was the TRUE winner of that "shootout" ;-)

My money is still on the Zipp Firecrest 808s. In the shootout, the FC were equipped with some pretty unaero Vittoria Corsas EVOs.
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Re: New Crr roller data [Nick_Barkley] [ In reply to ]
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the holy grail of tire knowledge... what tubulars to run with my 808 FC wheels?

Nick_Barkley wrote:
Tom A. wrote:

Yeah...not as bad...but it also has me thinking about which wheelset was the TRUE winner of that "shootout" ;-)


My money is still on the Zipp Firecrest 808s. In the shootout, the FC were equipped with some pretty unaero Vittoria Corsas EVOs.

Eric Reid AeroFit | Instagram Portfolio
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Re: New Crr roller data [ericM35-39] [ In reply to ]
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Think you became the authority on polarized training after you read one sportsci.org article?

To answer your question: Vittoria Corsa SL tubular
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Re: New Crr roller data [Tom A.] [ In reply to ]
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I keep thinking how well that tire would work on something like the Bontrager Aeolus 9, or a Firecrest 808...especially considering it's "shape" can't be any worse than the R3 tire shown in this Bontrager plot (and it most likely has a MUCH better Crr):

That high yaw data is "meh" anyway IMO. If I'm riding a TT and have 15 deg yaw, then I'll probably be too worried about keeping a decent line to care about a little wheel drag.

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Re: New Crr roller data [Tom A.] [ In reply to ]
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That settles it. Vittoria Evo Tri on the front and Vittoria Evo Slick on the rear!

Thanks for the work Tom!

"One Line Robert"
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Re: New Crr roller data [Nick_Barkley] [ In reply to ]
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It sucks that I have to use pink with most of you

Eric Reid AeroFit | Instagram Portfolio
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“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.â€
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Re: New Crr roller data [Tom A.] [ In reply to ]
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While the Evo slick tested well is it not that aero which is part of the equation too? How well aerodynamically does the Evo Triathlon fair?

Tom, will the Michelin Pro 4 be tested any time soon? I don't race on them but I do train on them.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Tom A. wrote:
dmorris wrote:
Wow, thanks for doing this!

That's gotta make you feel pretty good about your narrow Jet 90 with the Conti SS20 that was in the Mavic Wind Tunnel Challenge. Those Mavic Powerlink tires are slooooowwwww.


Yeah...not as bad...but it also has me thinking about which wheelset was the TRUE winner of that "shootout" ;-)

Thanks for sharing your numbers, much appreciated :)

I'm thinking about getting a Jet 9 C2 for the front and using SuperSonic 23mm on them. If you look at e.g. the numbers from the Mavic tunnel challenge it doesn't seem like the extra width of the new rims are hurting the drag at low yaw very much and that a tire such as the 23mm SS might more than make up for that in Crr. Plus you get that nice nice dip in drag when the yaw is getting higher (which is admittedly not that often, though).
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Re: New Crr roller data [MTM] [ In reply to ]
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Hi Tom, Awesome data and thanks alot for the detailed info! Do you have any idea where the conti GP 4000s would fit into your graph? Was there a reason you didn't test that specific tire? It seems like a good choice for firecrest wheels considering what Josh from zipp and jordan seem to think. Great work!

"I swim because that's how I get to ride my bike."

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Re: New Crr roller data [jackmott] [ In reply to ]
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jackmott wrote:
20mm up front all the way man

I remember Josh Portner talking on here about using 20mm on the 808FC and from his reply I got the feeling that the use of a narrow tire primarily decreased drag at higher yaw angles - perhaps most significantly by increasing the stall angle kind of like what can be seen with R3 vs. R4 Aero on the Aeolus drag charts Tom has posted. Intuitively it does make sense, since the frontal area (which is a bigger determining factor at low yaw) is not increased by a 23mm tire on these wider rims.

If this is indeed the case, a 23mm SuperSonic can very well provide the lowest total drag force (aero + Crr) at low yaw angles compared to a 20mm SuperSonic.

I would love to see a drag chart for 20mm vs. 23mm SuperSonic on 808FC, Jet9 C2, Aeolus 9 D3 or the like. Then we would have a much better idea :)
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff said "I think I'll be sticking with the Supersonics, though. "

Are there any know problems with Continental GP Supersonic availability? My guy says only 7 left in the US and thinks they are being discontinued. I don't know if he has access to all distributor data or just one.

Is this the Supersonic that we are talking about?

I too would like to see the Continental 4000GPS tested.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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This is all very interesting, but I am wondering if anyone could summarize at this point. What's the final verdict?
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Re: New Crr roller data [MTM] [ In reply to ]
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MTM wrote:

I would love to see a drag chart for 20mm vs. 23mm SuperSonic on 808FC, Jet9 C2, Aeolus 9 D3 or the like. Then we would have a much better idea :)

its come up a few times. like when the stinger crushed the 808 when it had a 21mm tire on it, which voids the warranty on the stinger and rapp got all upset.

a 20mm supersonic on a wide HED Jet fits like a glove while many 23mm tires still have a bit of a bulb shape.



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
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Re: New Crr roller data [HRPlbg] [ In reply to ]
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Biketiresdirect.com has the Supersonics in both sizes. I have used this tire on the front for the past year including some rough road conditions (St. George) and have had no issues despite its fragile appearance


Coach at KonaCoach Multisport
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Re: New Crr roller data [rruff] [ In reply to ]
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Thanks to both your rruff and TomA for picking up this torch from AFM and running (er, rolling) with it!
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Re: New Crr roller data [Dopers.Suck] [ In reply to ]
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Dopers.Suck wrote:
Hi Tom, Awesome data and thanks alot for the detailed info! Do you have any idea where the conti GP 4000s would fit into your graph?

Based on AFMs testing, about in the range of the Challenge Forte clincher and the Bonty AW19, or slightly worse...

Quote:
Was there a reason you didn't test that specific tire?

Ummm...I didn't have one handy?

http://bikeblather.blogspot.com/
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Re: New Crr roller data [Noof] [ In reply to ]
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Noof wrote:
This is all very interesting, but I am wondering if anyone could summarize at this point. What's the final verdict?

Sure. How about this?

Life is too short to run crappy rolling tires, and look! You too can figure out which is which ;-)

http://bikeblather.blogspot.com/
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Re: New Crr roller data [HRPlbg] [ In reply to ]
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The 4000GPS was tested in the original post. He found a road Crr of 0.0038, which would translate to about 35 watts @ 40 kph on Tom's graph.
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Re: New Crr roller data [Dopers.Suck] [ In reply to ]
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Do you have any idea where the conti GP 4000s would fit into your graph?

I tested another one that was well worn, and it did a little better than the first... which is quite good considering what kind of tire it is.

But I also have another (newer) Attack that is at the other end of the spectrum (Crr> .004 on my chart). It's built like a GP4000S only with thinner tread. That one really has me baffled. Maybe the tread compound is different or something...

I've also tested 5 20mm Supersonics. All were very good... some a little better than others. The newness and tread wear didn't seem to matter.




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Re: New Crr roller data [rruff] [ In reply to ]
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Ok, thanks for very much for the great info and insight into tires! For me the GP 4000s will be perfect for most of my road racing and training. I'll switch to supersonics or vittoria evo triathlon for my TT events. Cheers

"I swim because that's how I get to ride my bike."

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Re: New Crr roller data [HRPlbg] [ In reply to ]
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Are there any know problems with Continental GP Supersonic availability? My guy says only 7 left in the US and thinks they are being discontinued.

Probably because you can buy them retail overseas for less than US wholesale. But that's true of a lot of tires. If Conti quits making them, I'll be mildly upset. It's the only good 20mm tire I know of.

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Re: New Crr roller data [Noof] [ In reply to ]
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What's the final verdict?

Convince everyone you want to beat to use slow tires with liners and thick tubes... to prevent flats... because, you know... there is *nothing* worse than getting a flat in a race. And one tire isn't really faster than another. All this tire rolling resistance BS is a bunch of hype.

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Re: New Crr roller data [rruff] [ In reply to ]
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I've been in a number of plants that make car parts using rubber, seals, mounts etc. Its amazing how much goes into formulating and forming the rubber itself and a lot the materials are natural products.

It wouldn't surprise me a bit if some of the difference is batch to batch variation of the rubber. I also wonder if some of the lore of aging tires might not be true. Tires outgas for quite some time and many rubber compounds will continue to cross link for quite a bit of time. Some variation may come form age.

Styrrell
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Re: New Crr roller data [rruff] [ In reply to ]
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haha thank you for entertaining me, I had some more time to read through...

GP4000S for training, Open Corsa SL for racing.


Thank you for the time you lads put into this, it's quite valuable and I greatly appreciate it!
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Re: New Crr roller data [MTM] [ In reply to ]
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MTM,

Josh also posted once a curve comparing different tires on the 303 Firecrest carbon clincher, on that graph the narrower Conti Attack would make the wheel stall earlier than the wider GP4000S would.

So I guess it is a case to case basis, hard to make a general rule, don't you think ?

As for the 23mm Supersonic, taking into account that is is quite narrow (width similar to 22mm Attach) for a 23mm and that it is quite faster than the 20mm Supersonic, I think it is a good match for the wider rims we use these days. Though not a concern for some, we need to keep in mind also that a 20mm tire doesn't fit as securely on a rim with hook to hook width of 16mm and more then a 22-23mm tire would... but experience is best in that case and I haven't used any narrow tire on my firecrest wheels so can't tell for sure.
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Re: New Crr roller data [jackmott] [ In reply to ]
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jackmott wrote:
MTM wrote:

I would love to see a drag chart for 20mm vs. 23mm SuperSonic on 808FC, Jet9 C2, Aeolus 9 D3 or the like. Then we would have a much better idea :)


its come up a few times. like when the stinger crushed the 808 when it had a 21mm tire on it, which voids the warranty on the stinger and rapp got all upset.

a 20mm supersonic on a wide HED Jet fits like a glove while many 23mm tires still have a bit of a bulb shape.

I think the 'crushing' part was mostly the significantly higher stall angle? I don't recall exactly, but I remember Josh and/or Rapp said the new 808FC (the older 808 was tested) would be even better then the Stinger tested and at least from Zipp's own graphs the 808FC is only significantly better past 10 degrees because of a higher stall angle.

I have both had a 20mm and a 23mm mounted on my Jet Disc C2, which I think is more or less the same rim as the other Jet C2 rims. The 23mm has a little bit of bulb shape, though not very much IIRC. The 20mm is even narrower than the brake tracks.
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Re: New Crr roller data [pyf] [ In reply to ]
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pyf wrote:
MTM,


Josh also posted once a curve comparing different tires on the 303 Firecrest carbon clincher, on that graph the narrower Conti Attack would make the wheel stall earlier than the wider GP4000S would.

So I guess it is a case to case basis, hard to make a general rule, don't you think ?

As for the 23mm Supersonic, taking into account that is is quite narrow (width similar to 22mm Attach) for a 23mm and that it is quite faster than the 20mm Supersonic, I think it is a good match for the wider rims we use these days. Though not a concern for some, we need to keep in mind also that a 20mm tire doesn't fit as securely on a rim with hook to hook width of 16mm and more then a 22-23mm tire would... but experience is best in that case and I haven't used any narrow tire on my firecrest wheels so can't tell for sure.


I recall those graphs and found them:

http://www.carbonconnection.com/product_images/uploaded_images/303-drag-chart.png
http://i41.tinypic.com/2lmnc54.png


Not that much difference between the stall angles, but sure, there is a little. Attack and GP4000S perhaps also have different shapes, so really hard to judge the two graphs from only the tire widths.


A more interesting thing is perhaps to compare 23mm vs. 25mm GP4000S. Eyeballing it there seems to be 10-15g of extra aerodynamic drag from 0-10 degrees or roughly 1-2W. If it is the same difference between 20mm and 23mm SuperSonic it is not impossible the better Crr of the 23mm could more than make up for it. Best (only?) way is probably for me to try and do some field testing on it and see if I can tease out any difference.


Narrow tires and wide rims could indeed cause problems (more of a problem with silk-based tires I have heard). I have used 20mm SuperSonic on both Jet Disc C2 and Jet 6 C2 without problems, though. But I know Carl Matson from Trek is strongly discouraging using 20mm tires on the new wider rims.
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Re: New Crr roller data [ In reply to ]
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No what we've seen Tom's results on the Vittoria, we need to check the 2013 Vittoria Open Corsa SL, two main changes : it is now a 22 (used to be a 23) and it has Isogrip. If rolling resistance is still good, aero slightly better from the change in width and grip better with Isogrip it could be the kind of tire we are all looking for (the triathlon 22 is quite good but lacks the grip of Isogrip) ;-) .

Vittoria website : http://www.vittoria.com/...-tires/#product-4486

New specs :


28"22-622 700x22c 210gr product code : 111.360.SC.22.111BX
Open Corsa SL - Technical table
Last edited by: pyf: Feb 21, 13 3:15
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Re: New Crr roller data [pyf] [ In reply to ]
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Looks interesting. I've had bad experiences with Vittoria Corsa tires, though. They're very good on dry roads, but I have found them lethal on wet roads. They simply lose grip early and suddenly. Maybe that's something they have tried to change with Isogrip?

Edit: Also, usually the Vittoria Corsa tires don't do too well aerodynamically. I don't know if the Triathlon is any better.
Last edited by: MTM: Feb 21, 13 3:22
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Re: New Crr roller data [rruff] [ In reply to ]
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Do you know which model year the new Attack you have tested is? I know they have upgraded the Attack/Force for 2013 so it has a lower weight and perhaps then also different (better?) Crr.
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Re: New Crr roller data [MTM] [ In reply to ]
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I bought the slow Attack last summer. The fast one a couple years ago at least.
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Re: New Crr roller data [MTM] [ In reply to ]
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MTM wrote:
Looks interesting. I've had bad experiences with Vittoria Corsa tires, though. They're very good on dry roads, but I have found them lethal on wet roads. They simply lose grip early and suddenly. Maybe that's something they have tried to change with Isogrip?

Edit: Also, usually the Vittoria Corsa tires don't do too well aerodynamically. I don't know if the Triathlon is any better.

If you're referring to CX models, I have to say that I personally don't like the CX treads...neither the compound, nor the "file tread" on the sides. Both seem to me to make that tire a less than stellar cornering choice.

The SL type tread, along with what appear to be the predeccessors (i.e. the Bontrager RXL Pro Open, and the S-Works Mondo Open) isn't like that IME.

BTW, I thought that the 23C SLs I bought have the "isogrip" nomenclature on them. I'll check later...

http://bikeblather.blogspot.com/
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Tom A. wrote:
MTM wrote:
Looks interesting. I've had bad experiences with Vittoria Corsa tires, though. They're very good on dry roads, but I have found them lethal on wet roads. They simply lose grip early and suddenly. Maybe that's something they have tried to change with Isogrip?

Edit: Also, usually the Vittoria Corsa tires don't do too well aerodynamically. I don't know if the Triathlon is any better.


If you're referring to CX models, I have to say that I personally don't like the CX treads...neither the compound, nor the "file tread" on the sides. Both seem to me to make that tire a less than stellar cornering choice.

The SL type tread, along with what appear to be the predeccessors (i.e. the Bontrager RXL Pro Open, and the S-Works Mondo Open) isn't like that IME.

BTW, I thought that the 23C SLs I bought have the "isogrip" nomenclature on them. I'll check later...

Yes, I have only tried the CX models - both in 290 and 320 TPI. They are scary on wet roads.

Is the SL another thread compound or the same but with a slick thread? Also, does it have the same ridge on the sides like the CX? Same question for the Triathlon.... I'm thinking that might contribute to the below par aerodynamics.
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Re: New Crr roller data [MTM] [ In reply to ]
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The Triathlon has a slick center and "roughened" side tread. There is a lip where the tread meets the sidewall. I don't know of any "open tubular" (glued on tread) tire that does not have this. The tire is otherwise very smooth though, unlike molded tires that tend to have a lot of small ridges and bits sticking out.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Would love to see some up to date CRR data on the Conti GrandPrix TT clincher and Conti podium TT tub tires?


If you are sure you will fail, or convinced you will succeed, you are probably right.....
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Re: New Crr roller data [MTM] [ In reply to ]
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did i just get a couple of the wrong size tires???!!! 20vs23 SS
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Re: New Crr roller data [jeffp] [ In reply to ]
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what is the weight of the ss 23 in real life vs the SS 20 ?

the SS23 must be extremely thin compared to the SS20

on contis site the difference is only stated as 5 gram...

but some other people are taking 137 and 140 for the SS20 ....
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Re: New Crr roller data [fastupto] [ In reply to ]
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My 20 ss is 135g.
My 23 ss is 160g.
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Re: New Crr roller data [jeffp] [ In reply to ]
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I don't know which size you got, but after thinking some more about it the 23mm will probably have a hard time being faster on the front. The Crr difference seems to be ~1W for one wheel, which is probably less than the aerodynamic difference between the sizes, at least if looking at some of the Zipp graphs for the 303FC. Of course, we don't know exactly how 20mm vs. 23mm do aerodynamically on something like a 808FC or Jet 9 C2.
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Re: New Crr roller data [MTM] [ In reply to ]
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may have to ship wheel to tunnel with buddy so he can check :)
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Re: New Crr roller data [jeffp] [ In reply to ]
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i put 20 ss on 808, fit does not loof too bad, only thing of note is i need a smaller latex tube size and the result is that the front wheel is almost 10mm shorter, so in esence lowered front end 4-5mm. will require adjusting bars and saddle if i stay on this route. not going to 20mm on rear
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Re: New Crr roller data [jeffp] [ In reply to ]
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That would be sweet. I don't think I'm the only one interested in 20mm vs. 23mm SuperSonic aerodynamic performance on a new wide rim.
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Re: New Crr roller data [MTM] [ In reply to ]
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The Crr difference seems to be ~1W for one wheel, which is probably less than the aerodynamic difference between the sizes, at least if looking at some of the Zipp graphs for the 303FC.

One thing to consider is that the 20mm tire would normally be pumped to a higher pressure... I think even to achieve a similar vibration response. Not sure about that, though.

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Re: New Crr roller data [MTM] [ In reply to ]
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MTM wrote:
That would be sweet. I don't think I'm the only one interested in 20mm vs. 23mm SuperSonic aerodynamic performance on a new wide rim.

I put both a Bonty R4 and a 20mm SuperSonic on an 808 FC. I couldn't figure out which looked more aero. The SuperSonic was narrower but made a less smooth transition than the R4.

So is the difference between the top tires, combining bot aero and crr effects, going to be large enough that one could measure with self testing and the golden cheeta software? Or will it be in the noise? I'd think subtle body positions on the bike and changes in wind patterns throughout the day would dominate the difference between say the top 5 tires?

Assuming that's true, the best one can do is look at this data, eyeball the aerodynamics, make a decision move on?
Last edited by: matto: Feb 23, 13 10:07
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
The Crr difference seems to be ~1W for one wheel, which is probably less than the aerodynamic difference between the sizes, at least if looking at some of the Zipp graphs for the 303FC.

One thing to consider is that the 20mm tire would normally be pumped to a higher pressure... I think even to achieve a similar vibration response. Not sure about that, though.

Yes, probably. Not sure it would affect things too much. Perhaps the 23mm is better if the surface is sufficiently rough/bad.
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Re: New Crr roller data [matto] [ In reply to ]
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matto wrote:
MTM wrote:
That would be sweet. I don't think I'm the only one interested in 20mm vs. 23mm SuperSonic aerodynamic performance on a new wide rim.


I put both a Bonty R4 and a 20mm SuperSonic on an 808 FC. I couldn't figure out which looked more aero. The SuperSonic was narrower but made a less smooth transition than the R4.

So is the difference between the top tires, combining bot aero and crr effects, going to be large enough that one could measure with self testing and the golden cheeta software? Or will it be in the noise? I'd think subtle body positions on the bike and changes in wind patterns throughout the day would dominate the difference between say the top 5 tires?

Assuming that's true, the best one can do is look at this data, eyeball the aerodynamics, make a decision move on?


Probably next to impossible to tell which of those two tires is actually more aero without windtunnel or very stringent field testing. Could probably even depend on yaw. Based on the various Crr tests I've seen I feel confident that the 20mm SuperSonic is the faster overall tire, though.

Regarding field testing, it likely depends on your protocol and how meticulous you are. If not very meticulous you will probably have a very hard time to tell the difference between the five best tires. If you have any wind and are not measuring it precisely, forget about finding differences smaller than, say 5 watts.
Last edited by: MTM: Feb 23, 13 10:16
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Re: New Crr roller data [Tom A.] [ In reply to ]
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I'm in need of a new rear tire as my 290 TPI Evo CX's are going to seed and making me flat-nervous. Might as well get some faster rubber in the process. :)

It looks like I can get Conti SS's 23's for slightly less than Evo Tri's. (unless I can convince some teammates to join in a tire/tube buying spree)


So, in your estimation, which would you use attached to a 23mm wide rim (on the rear wheel) for tri's?

Read: given the closeness in RR, which would you assume is more durable?

The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock
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Re: New Crr roller data [Derf] [ In reply to ]
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The Evo Tri probably has better tread life... the SS is only good for <500mi on the rear... under me anyway. Puncture resistance is probably a toss up. Even though they have no vectran belt, the SS tires aren't that fragile.

I've done some more tests and I'd give the SS the clear Crr edge. The more I run it the faster it gets. It had been laying around for a couple years, so maybe there is an aging and re-break-in thing going on... pure speculation.

Another thing... the Vittorias are very nice tires... they just look and feel better crafted than the Continentals.
Last edited by: rruff: Feb 25, 13 14:41
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Re: New Crr roller data [Derf] [ In reply to ]
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Derf wrote:
I'm in need of a new rear tire as my 290 TPI Evo CX's are going to seed and making me flat-nervous. Might as well get some faster rubber in the process. :)

It looks like I can get Conti SS's 23's for slightly less than Evo Tri's. (unless I can convince some teammates to join in a tire/tube buying spree)


So, in your estimation, which would you use attached to a 23mm wide rim (on the rear wheel) for tri's?

Read: given the closeness in RR, which would you assume is more durable?

I think the EVO tri actually has a puncture belt (it's hard to tell from the Vittoria literature any more)...whereas, the SS does not. I'm pretty sure the EVO Slick has one as well, and it's virtually tied with the EVO Tri.

http://bikeblather.blogspot.com/
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Re: New Crr roller data [rruff] [ In reply to ]
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Forgot to reply after your's and Tom's posts. Thank you both! I think I'm going to seek out a Vittoria for longer course racing (even if I'm being unfounded in my risk aversion), and use a SS that I'm getting from a friend (used once) for shorter course stuff.

The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock
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Re: New Crr roller data [Derf] [ In reply to ]
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Regarding "risk aversion"... even though they don't have great puncture resistance, neither of these tires are going to fall apart on you.

Probably the best thing you can do to avoid punctures during a race is to stay in the lane and off the shoulder if you can. Vehicles naturally "sweep" the lane just by driving on it, but a lot of the crap ends up on the shoulder.
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Re: New Crr roller data [rruff] [ In reply to ]
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Was thinking Ron after I mounted up an attack last night - they are directional (arrow on the sidewall). Any chance that 2nd, poorer testing Attack, was mounted backward? Not sure it would make much of a difference?

____________________________________
Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD
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Re: New Crr roller data [rroof] [ In reply to ]
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Nope. Doubt it would matter at all though. The grooves are just for style.

I'll soon have a new Attack and Force ready to test. I've also revised the protocol a little to reduce random errors, and I think I'll spend a day and test (or retest) every tire I have.
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Re: New Crr roller data [Tom A.] [ In reply to ]
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digging up an old post... Tom, would you expect the tubular version of the SL to perform/have similar differences to to the tubular CX as you outlined below?

I'm looking for replacements for my tubular 23mm CX or tubular 21mm Tangente for my FC 808s. Wondering if a Crono might be doable for TTs.

Tom A. wrote:
Fleck wrote:
I can't seem to get away from the Corsa Evo tire when it comes to racing

Racing?

I ride them all the time!

Every ride, a thing of beauty.

Why ruin a great ride with cheap rubber?

The knock on the Vittoria EVO CX historically has been that it's not that durable and does not last that long. We ride on shitty roads, and I don't seem to get an unusual number of flats ( on average 1 - 3/year) and for the riding I do - a moderate amount - they last a full season of outdoor riding. That's fine for me.

The Conti GP 4000s is the one that intrigues me. It's close to the Vittoria's in rolling resistance, but reports seem to say it's more durable and lasts longer. Maybe I'll change things up this year and go with a set of bad-ass
Conti GP 4000s 25's! :)


Take a look at the Vittoria EVO Corsa SL instead of the CX if you're considering the GP4000s. The tread compound is different than the CX (feels more like what was used on the Bontrager and Specialized "open tubular" models which were smokin' fast tires and had great durability and grip IME) and there's no "herringbone" tread pattern (it's slick, thus the "SL" moniker). I've found them to be fairly durable AND they handle better than the CXs IMHO. I've always found the CXs to handle a bit "wobbly" and the tread compound seems too soft and easily cut.

I haven't thrown one on the rollers yet (possibly this weekend), but I don't expect it to test "slow" either... ;-)


Eric Reid AeroFit | Instagram Portfolio
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Re: New Crr roller data [ericM35-39] [ In reply to ]
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ericM35-39 wrote:
digging up an old post... Tom, would you expect the tubular version of the SL to perform/have similar differences to to the tubular CX as you outlined below?

Yup.

http://bikeblather.blogspot.com/
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
Nope. Doubt it would matter at all though. The grooves are just for style.

I'll soon have a new Attack and Force ready to test. I've also revised the protocol a little to reduce random errors, and I think I'll spend a day and test (or retest) every tire I have.

Any chance the Pro4 Comp will make the test?

-------------------
Madison photographer Timothy Hughes | Instagram
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Re: New Crr roller data [rruff] [ In reply to ]
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Wow, this is great information, thanks. As someone just starting to really focus on the little aspects of racing, in the real world, how much time would the best tire listed here save over the middle range tire such as the mich 4? seconds, minutes? Based on what I think are accurate calculations, it would equate to about 0.45 MPH. Does this sound right? Thanks for any feedback.
Last edited by: mgratton33: Mar 10, 13 19:25
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Re: New Crr roller data [Tom A.] [ In reply to ]
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Thanks

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Re: New Crr roller data [Timtek] [ In reply to ]
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Not unless someone wants to send me theirs. I might be inspired to buy a Pro4 Comp *Limited*...
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Re: New Crr roller data [mgratton33] [ In reply to ]
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Sounds about right.
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Re: New Crr roller data [rruff] [ In reply to ]
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Wow, not only did I get the math right, but I may have also found a way to buy some speed. Half a mile per hour for $90 almost seems like a no brainer. Thanks again for the data and your time, it's very appreciated.
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Re: New Crr roller data [MTM] [ In reply to ]
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MTM wrote:
That would be sweet. I don't think I'm the only one interested in 20mm vs. 23mm SuperSonic aerodynamic performance on a new wide rim.

I answered this question here in this forum may be 2 years ago, just use the search option!
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Re: New Crr roller data [BergHügi] [ In reply to ]
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BergHügi wrote:
MTM wrote:
That would be sweet. I don't think I'm the only one interested in 20mm vs. 23mm SuperSonic aerodynamic performance on a new wide rim.

I answered this question here in this forum may be 2 years ago, just use the search option!

I almost forgot. But more data is usually better and having data at different yaw angles would also be neat :-)
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Re: New Crr roller data [rruff] [ In reply to ]
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Ron, any knowledge about Vittoria Cronos? The tubular 20mm tested very fast with AFM, and now I see the new version is 22mm "to match better with wide rims" and has a puncture belt. Did the old one have a puncture belt?

best case, the Crono will have even less Crr for additional width but less aero due to the wider 22mm. Not a bad tire for the State TT Champs or something like that.

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Re: New Crr roller data [ericM35-39] [ In reply to ]
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The new one measures 21mm, and was lower in Crr in AFMs testing. The old didn't have a puncture strip. I've used a pair for a IM race with no issues and they still look new.

Styrrell
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Re: New Crr roller data [styrrell] [ In reply to ]
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AFM Rev 9 testing or some other stuff he did? On Rev 9 I think the Crono tested was a 20mm.

yeah, the Crono looks good in tubular since the Triathlon version that Tom A. and rruff tested is butyl. Both of those guys also recommended the SL but why go with the SL when the Crono will do.

also, 21mm is a nice width. This is thinner than the 22mm quoted. How does it look mated up to your wheels. Which wheels do you have?

thx.

styrrell wrote:
The new one measures 21mm, and was lower in Crr in AFMs testing. The old didn't have a puncture strip. I've used a pair for a IM race with no issues and they still look new.

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Re: New Crr roller data [ericM35-39] [ In reply to ]
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Its testing he did after rev 9. I think offically its called the crono II but most catalogues just call it the crono. The easiest way to tell for sure is the new one uses the replaceable red valve.

I have an original model zipp disc and a H3. mates up fine but I fill in the gap between the rim and tire with gasket compound.

Styrrell
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Re: New Crr roller data [styrrell] [ In reply to ]
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styrrell wrote:
mates up fine but I fill in the gap between the rim and tire with gasket compound.

think that affects Crr? I thought I read somewhere that it does. Either way, sounds fast.

Anyway, thanks for the info. I think I'll go Crono 20mm front and 22mm rear for the state TT and then Crono 22mm front and either CX or SL 23mm rear for Ironman

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Re: New Crr roller data [ericM35-39] [ In reply to ]
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ericM35-39 wrote:
styrrell wrote:
mates up fine but I fill in the gap between the rim and tire with gasket compound.


think that affects Crr? I thought I read somewhere that it does. Either way, sounds fast.

Anyway, thanks for the info. I think I'll go Crono 20mm front and 22mm rear for the state TT and then Crono 22mm front and either CX or SL 23mm rear for Ironman

Liquid latex does NOT affect Crr - not sure what the gasket compound that styrrell is using ?? The newer and wider Crono 22 tested ~ 0.00226 IIRC and measured ~ 21 mm in width so really not much bigger than the older Crono 20 which did indeed measure ~ 20 mm. Vittoria now actually has a new version of the Crono that is even wider - 24 mm again IIRC. Haven't tested one of these. The spreadsheet is way out of date but there are some threads on BTR which have some more recent data. I haven't tested many tires lately due to some very gratifying but time consuming family contstraints.
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Re: New Crr roller data [AFM] [ In reply to ]
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AFM wrote:
I haven't tested many tires lately due to some very gratifying but time consuming family contstraints.

don't matter, had sex!



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Re: New Crr roller data [AFM] [ In reply to ]
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AFM wrote:
The newer and wider Crono 22 tested ~ 0.00226 IIRC and measured ~ 21 mm in width so really not much bigger than the older Crono 20 which did indeed measure ~ 20 mm.


Doesn't that make the new 22mm Crono the fastest road tubular out there? Sorry don't have my AFM 9 in front of me ;)

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Last edited by: ericM35-39: Mar 11, 13 16:10
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Re: New Crr roller data [ericM35-39] [ In reply to ]
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ericM35-39 wrote:
AFM wrote:
The newer and wider Crono 22 tested ~ 0.00226 IIRC and measured ~ 21 mm in width so really not much bigger than the older Crono 20 which did indeed measure ~ 20 mm.


Doesn't that make the new 22mm Crono the fastest road tubular out there? Sorry don't have my AFM 9 in front of me ;)

Yes. The Pista I tested was slightly better and the Conti SS 23 with latex tube is ~ the same as the Crono 22 (only tested one tire). The weight on several of the Crono 22's is ~ 185 grams compared to the advertised weight of 165 grams. I've heard from one source that the reliability is improved over the older Crono 20.
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Re: New Crr roller data [AFM] [ In reply to ]
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thanks. And congrats on the time-consuming family constraints!

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Re: New Crr roller data [ericM35-39] [ In reply to ]
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ericM35-39 wrote:
And congrats on the time-consuming family constraints!

Thanks - parenting a grandchild definitely consumes time. But it's very rewarding.
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Re: New Crr roller data [AFM] [ In reply to ]
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Hello Al! Do you recall testing the Conti Podium TT or any of their track tubulars (which you can use in TTs)?
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
Hello Al! Do you recall testing the Conti Podium TT or any of their track tubulars (which you can use in TTs)?

Hi Ron, I haven't tested very many Conti tubulars. I did test a GP4000 which supposedly had the black chili compound but it was lightly glued but did not roll well - ~ 0.00384. IMO "proper gluing" would not have brought it up to TT racing consideration. Mounting it on the test wheel however did result in many blisters and colorful language - good thing the grandchild was not yet around the house. (:-)
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Re: New Crr roller data [MTM] [ In reply to ]
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MTM wrote:
That would be sweet. I don't think I'm the only one interested in 20mm vs. 23mm SuperSonic aerodynamic performance on a new wide rim.
Did the ST collective reach a consensus on this?
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Re: New Crr roller data [jeffp] [ In reply to ]
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Why would you readjust your fit because the tire lowers the front. Your contact points on the bike are exactly the same. I suppose the "aero" might be different but are you sure that you've got it dialed in so closely that it needs to be changed.

Styrrell
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Re: New Crr roller data [Andrew69] [ In reply to ]
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Andrew69 wrote:
MTM wrote:
That would be sweet. I don't think I'm the only one interested in 20mm vs. 23mm SuperSonic aerodynamic performance on a new wide rim.
Did the ST collective reach a consensus on this?

all of the data points I've seen so far on the question of narrow tires on wide rims suggest narrow tires are faster on wide rims.

The zipp 303 *may* be an exception.



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Quote Reply
Re: New Crr roller data [styrrell] [ In reply to ]
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Quote:
Why would you readjust your fit because the tire lowers the front. Your contact points on the bike are exactly the same. I suppose the "aero" might be different but are you sure that you've got it dialed in so closely that it needs to be changed.
Styrrell

When you swap from a 23mm front tire to a 21mm front tire Your CG shifts backward by .34mm and down by .19mm so your weight distribution on the bike changes drastically.

It's just more of the typical triathlete princess-and-the-pea BS.

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Re: New Crr roller data [ZackC.] [ In reply to ]
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Oh I dunno, I'm quite the princess and that seems like a pea to me =)

ZackC. wrote:

When you swap from a 23mm front tire to a 21mm front tire Your CG shifts backward by .34mm and down by .19mm so your weight distribution on the bike changes drastically.

It's just more of the typical triathlete princess-and-the-pea BS.



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Freelance sports & outdoors writer Kathryn Hunter
Quote Reply
Re: New Crr roller data [ZackC.] [ In reply to ]
Quote | Reply
ZackC. wrote:
Quote:
Why would you readjust your fit because the tire lowers the front. Your contact points on the bike are exactly the same. I suppose the "aero" might be different but are you sure that you've got it dialed in so closely that it needs to be changed.
Styrrell


When you swap from a 23mm front tire to a 21mm front tire Your CG shifts backward by .34mm and down by .19mm so your weight distribution on the bike changes drastically.

It's just more of the typical triathlete princess-and-the-pea BS.

Backwards? Geometry says that CG will move forwards and down (counterclockwise).

That said, I can't tell the difference in ride height between tires. Tire grip and "feel"...yes.

The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock
Quote Reply
Re: New Crr roller data [Derf] [ In reply to ]
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Derf wrote:
ZackC. wrote:
Quote:
Why would you readjust your fit because the tire lowers the front. Your contact points on the bike are exactly the same. I suppose the "aero" might be different but are you sure that you've got it dialed in so closely that it needs to be changed.
Styrrell


When you swap from a 23mm front tire to a 21mm front tire Your CG shifts backward by .34mm and down by .19mm so your weight distribution on the bike changes drastically.

It's just more of the typical triathlete princess-and-the-pea BS.


Backwards? Geometry says that CG will move forwards and down (counterclockwise).

That said, I can't tell the difference in ride height between tires. Tire grip and "feel"...yes.

I was being facetious.

But, if you want to get technical wit' it...

It all depends on the rider's position. Betweeen 180 and 270 degrees CCW from east (0) any further CCW rotation results in the vector projected length along the x-axis to shorten, whereas between 90 and 180 the projected length along the x-axis increases. For a rider in a very upright position I would imagine that the aforementioned tire swap would result in the CG moving forward a minuscule amount. For a rider in a great TT position with a flat back they may already be configured with the forward-most possible CG location such that any further CCW torso rotation (viewed from the non-drive side) results in the CG moving backward a minuscule amount.

BUT: This is definitely a case where 5mm is not 5mm. If by switching tires you lose 5mm of height on your front wheel this is not the same as losing 5mm height at your aerobar pads. If we assume for the sake of argument that the distance between your hips and your pads is 30cm and the distance between your seat and your wheel contact point is 1m, we can figure out some angles. Change in torso angle due to wheel radius change: tan(.005/1)=~.25degrees, whereas the change in torso angle due to pad height change: tan(.005/.3)=~.95degrees. This is more or less why you should give zero bothers about your front wheel radius/diameter as it pertains to your bike fit.


For the mathy folks: (caveat: small angle approximation)

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Re: New Crr roller data [ZackC.] [ In reply to ]
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Re: New Crr roller data [ZackC.] [ In reply to ]
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It all depends on the rider's position. Betweeen 180 and 270 degrees CCW from east (0) any further CCW rotation results in the vector projected length along the x-axis to shorten, whereas between 90 and 180 the projected length along the x-axis increases. For a rider in a very upright position I would imagine that the aforementioned tire swap would result in the CG moving forward a minuscule amount. For a rider in a great TT position with a flat back they may already be configured with the forward-most possible CG location such that any further CCW torso rotation (viewed from the non-drive side) results in the CG moving backward a minuscule amount.

BUT: This is definitely a case where 5mm is not 5mm. If by switching tires you lose 5mm of height on your front wheel this is not the same as losing 5mm height at your aerobar pads. If we assume for the sake of argument that the distance between your hips and your pads is 30cm and the distance between your seat and your wheel contact point is 1m, we can figure out some angles. Change in torso angle due to wheel radius change: tan(.005/1)=~.25degrees, whereas the change in torso angle due to pad height change: tan(.005/.3)=~.95degrees. This is more or less why you should give zero bothers about your front wheel radius/diameter as it pertains to your bike fit.


Or you coulda just said this ;-)


"Your contact points on the bike are exactly the same. "

Styrrell
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Re: New Crr roller data [rruff] [ In reply to ]
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thank you for the data. on top of the results there is an estimate suggesting 0.005 = .17mph gain. is this per tire or for both tires?
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Re: New Crr roller data [vjohn] [ In reply to ]
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vjohn wrote:
I had Al test a Maxxis a few years ago, along with some Challenge Criteriums that did great. The Maxxis (it was their top of the line racing tire, forget the name) did terribly.

I did a TT with a friends powertap that had a maxis mounted. By far the worst time I have ever had on that course. We joked that maybe it was the tire and named the Maxis tires the "watt eaters". From the test data it looks like I was onto something.
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Re: New Crr roller data [rruff] [ In reply to ]
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I would love to see how this tire, the continental grand prix, fairs. Its a dumbed down version of the 4000


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Re: New Crr roller data [mgratton33] [ In reply to ]
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That estimate is for two tires.
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Re: New Crr roller data [rruff] [ In reply to ]
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I wouldn't call it dumbed down. It has a lower TPI casing, and a double PolyX breaker rather than Vectran. Still has Black Chili tread though, so it is probably a durable tire that isn't too slow.

The only tires I'd be inspired to buy and test would be promising race tires... or maybe everyday tires with a potential of being fast and cheap. If I want something a bit slower but cheaper and smooth riding, the Rubino Pros are hard to beat. PBK had those for $22 recently.
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
I wouldn't call it dumbed down. It has a lower TPI casing, and a double PolyX breaker rather than Vectran. Still has Black Chili tread though, so it is probably a durable tire that isn't too slow.

The only tires I'd be inspired to buy and test would be promising race tires... or maybe everyday tires with a potential of being fast and cheap. If I want something a bit slower but cheaper and smooth riding, the Rubino Pros are hard to beat. PBK had those for $22 recently.

I've been racing crits on a set of GPs for half a season and have really been impressed by them. But all prices being equal you would go for the Rubino?
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Re: New Crr roller data [cabdoctor] [ In reply to ]
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Friends don't let friends race with Rubinos. GP 4000s are the best clincher tires I've found for bike racing (not triathlons or tt's). Fairly durable and grip well. Also had good luck with Pro 3's if I only used them for racing and nothing else. The Pro 3's were always really good in wet weather.
Last edited by: nightfend: Mar 21, 13 11:15
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Re: New Crr roller data [cabdoctor] [ In reply to ]
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Nah... I'd get the GP if the price was the same. Haven't seen the GPs very cheap though.
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
Nah... I'd get the GP if the price was the same. Haven't seen the GPs very cheap though.

Pretty good deal going over at Probikekit right now on the GP4000s: http://www.probikekit.com/...ncher-road-tyre.html

-Dave
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Re: New Crr roller data [rruff] [ In reply to ]
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I have seen the non-4000 for under thirty.
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Re: New Crr roller data [rruff] [ In reply to ]
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Has anyone seen Crr data for the Veloflex Extreme tubular?

I am trying to decide which tires to put on a new set of TT wheels; HED Stinger disc and HED Stinger 9 front. Typically I would go with the Veloflex Carbon (23mm), but I wondering if besides a slight reduction in weight if the Extreme (22mm) would also offer a Crr benefit.
Quote Reply
Re: New Crr roller data [GONE4ARIDE] [ In reply to ]
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please refer to AFM Rev 9 for tubular data.

generally, properly glued is faster. heavier means nothing.

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Quote Reply
Re: New Crr roller data [ericM35-39] [ In reply to ]
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Thanks. I wasn't implying that the lighter Extreme would have a different Crr based on its weight. Compared to the Carbon, it has a higher thread count, a different tread pattern and it's a 22 vs. 23. These are the attributes that make me question how it's Crr compares.


ericM35-39 wrote:
please refer to AFM Rev 9 for tubular data.

generally, properly glued is faster. heavier means nothing.
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Re: New Crr roller data [GONE4ARIDE] [ In reply to ]
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no need to question... AFM probably has the data.

GONE4ARIDE wrote:
Thanks. I wasn't implying that the lighter Extreme would have a different Crr based on its weight. Compared to the Carbon, it has a higher thread count, a different tread pattern and it's a 22 vs. 23. These are the attributes that make me question how it's Crr compares.


ericM35-39 wrote:
please refer to AFM Rev 9 for tubular data.

generally, properly glued is faster. heavier means nothing.

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Quote Reply
Re: New Crr roller data [ericM35-39] [ In reply to ]
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Could someone please point me in the direction of AFM rev 9? Thank you.
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Re: New Crr roller data [GONE4ARIDE] [ In reply to ]
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try this




GONE4ARIDE wrote:
Could someone please point me in the direction of AFM rev 9? Thank you.

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Re: New Crr roller data [rruff] [ In reply to ]
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Thanks for this, it's incredibly useful!
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Re: New Crr roller data [rruff] [ In reply to ]
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So I ordered a pair of Vittoria Corsa SL's, and what I received are Open Corsa EVO Tech's (model #23-622). Anyone have any info on these...I don't even see them listed on the Vittoria site?

Thanks.

Scott
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Re: New Crr roller data [WiScott] [ In reply to ]
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I thought those were their "wet-grip" compound tires? And, if I'm remembering correctly, slower than the CX's, much less the SL's
:(

The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock
Quote Reply
Re: New Crr roller data [3Aims] [ In reply to ]
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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 rode supersonics. No concern of flats... Road debris gets out of my way when I'm blazing down the road.

:)

In all seriousness, I'm a conti fan. I rode supersonics, Gp 4000, and attack/ force. They are all great. Supersonics seemed noticeably faster. They "feel" fast on acceleration. Maybe a placebo, but anything that gives a mental advantage- I will take it!
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Re: New Crr roller data [rruff] [ In reply to ]
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Just wondering if you plan to test the Michelin Pro4 Comp?

Is it a real new tire? If yes, could be interesting to compare...

Thanks to share with us all this interesting data!

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Re: New Crr roller data [quickguru] [ In reply to ]
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I just ordered some stuff from Wiggle, and it looks like they have the Pro4 Comp LTD in stock for $50... but I didn't order it. It's only size 23 which is a little big on my rims.
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Re: New Crr roller data [rruff] [ In reply to ]
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any updates to this?

Wondering about Conti Force 24mm

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Re: New Crr roller data [ericM40-44] [ In reply to ]
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Tested 2 of them... no surprises. A hair better than Attacks on average.

But they are fat so I'd run Attacks front and rear. Turn them backwards.
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Re: New Crr roller data [rruff] [ In reply to ]
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well, for bike racing yeah but I'm thinking about running the Force 24mm on my Super-9 disc. It hides a 25mm GP4000s pretty well

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Re: New Crr roller data [ericM40-44] [ In reply to ]
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Pretty sure the trailing edge isn't hidden...
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
Pretty sure the trailing edge isn't hidden...
agreed. I still like rolling the Supersonics though. I have had great success, although did just flat at Texas 1.5 miles in. I suspect I was lucky enough to pick up a safety pin coming out of transition. With that being said I tried to wear out a Supersonic all spring in Tucson, 2000 (1000 front + 1000 rear) ride miles no flats.


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Quote Reply
Re: New Crr roller data [Thomas Gerlach] [ In reply to ]
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You got 1k miles out of a SS on the rear? Lots more than I ever have...
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
You got 1k miles out of a SS on the rear? Lots more than I ever have...

Yeah it was weird, I kept expecting them to be done in March but I kept using them and using them. It got to May and I was sure after 115 mile ride and 105 mile ride they were going to be done but nope. Lots of power, and lots of time going up hills. Very minimal breaking and smooth blacktop. I am personally very shocked about this set. All I can think of is that they wear out pretty quickly with hard braking and rougher surfaces. These weighed in the range of 170+ grams originally.


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Quote Reply
Re: New Crr roller data [Thomas Gerlach] [ In reply to ]
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They might be putting more rubber on them then. Think the heaviest 23 I have is ~155g and the 20s are 140g or less.
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Re: New Crr roller data [rruff] [ In reply to ]
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rruff wrote:
But they are fat so I'd run Attacks front and rear. Turn them backwards.

Say what? Backwards?
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Re: New Crr roller data [rruff] [ In reply to ]
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Anyone use the gp4000s II in a 20mm yet? I have one and a supersonic...debating which one to put on for a rough road racine 70.3 in July.
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Re: New Crr roller data [waupaca11] [ In reply to ]
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Some retailers are advertising the Attack/Force "ii" (as in version #2). Per Wiggle.com's description of the "ii":

Quote:
Updated for 2013, with an advanced BlackChili compound and reduced weight, our Vectran and Black Chili technologies have been radically applied to this uncompromising race tire set.

@rruff, do you know which version was used to gather the data?

@GreatScott, by "backwards", I think the idea is to mount an Attack on the rear, but with the rotation arrow facing the opposite direction as the front Attack, mimic'ing the Force's tread pattern:


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Re: New Crr roller data [415brian] [ In reply to ]
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Got it, thanks.

Now I'm just trying to understand the benefits of running the Attack in back. Won't the wider Force have lower Crr, with the aero penalty offset by being back in the wash?

Scott
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Re: New Crr roller data [415brian] [ In reply to ]
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Mine are pre II. I couldn't find anything on Conti's site about what might have changed... they don't even list them. Doubt the new ones are any better honestly.

Attacks are probably more aero if installed backwards, meaning that side grooves at the top of the wheel point towards the rear rather than front. That's based on Swiss Side's testing.
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Re: New Crr roller data [GreatScott] [ In reply to ]
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Where is the line where the better aero trumps the tiny Crr increase of a smaller tire? Don't know, but I suspect the Attack is already "too big". You can run fat tires if you want... but I won't be.
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Re: New Crr roller data [rruff] [ In reply to ]
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Agree the Force is fat. Nice fast rolling tire, bit of a plusher ride than the GP4000s, but rubs on the chain stay of my S2 when hammering around corners. Now I use GPS4000s back and Attack on the front. The Attack blends very smoothly with my narrow front wheel. Reckon it would blend well on my hed3 too, haven't had chance to try will when the Bont aero wears out.
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Re: New Crr roller data [rruff] [ In reply to ]
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I'll take that advice! How do wide rims affect your perspective on fat tires? For example, the 24.4mm Flo 60/90. Based on this and related threads, I was thinking the 22mm Attack and 24mm Force would be a nice fit. Now I'm thinking Attack/Attack or Atttack/GP 4000s.

Scott
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Re: New Crr roller data [GreatScott] [ In reply to ]
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On wide rims the clincher tires grow in width. The Force will be ~26mm wide on that rim, the Attack ~24mm.
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Re: New Crr roller data [rruff] [ In reply to ]
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I know this happens a lot on this site....Newbie looking for recommendations on what tire to use....but here we go!

Did sprint triathlons last year and doing Olympics this year leading up to the Rev3 Cedar Point Half in September.

I have a Trek Madone 3.1 and rode on the stock tires Bontrager R1 (700x23c) in 2012. Went into Bike Authority in Cleveland in the Spring of 2013 looking for new tires. They gave me the Vittoria Rubino Pro (Non-Slick) 700x23c and I used those during the 2013 triathlon season.

Stumbled on to this site to find that the Rubino Pros are probably not what I should be riding on, even though I was happy with the price tag at the time.

Looking for an upgrade in the $60 to $80 per tire range. Any suggestions?
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Re: New Crr roller data [rruff] [ In reply to ]
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Any feeling on how the Attack/Force would pair up with Enve 6.7s? My "windtunnel eyeball" makes me think the Attack "looked" too narrow for that wider front rim. **disclaimer I a novice on this stuff**. Thanks,
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Re: New Crr roller data [jmt8345] [ In reply to ]
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I wonder what you think there is about a narrow tire that would be detrimental to aero? I'd probably run 20mm Supersonics on those rims... but that's just me. If you think you'll be hitting potholes and rocks and stuff, then a bigger tire is warranted... but not for aerodynamics.
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Re: New Crr roller data [Grux] [ In reply to ]
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From everything I've seen Conti pretty much owns the market if you want fast tires with decent durability. They are usually cheapest from UK sites, like Ribble and Wiggle. The GP4000S 23 was $36 on Ribble for instance. And get Vittoria latex tubes (<$10) while you are at it. And make sure you install them right so you don't kill yourself.
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Re: New Crr roller data [jmt8345] [ In reply to ]
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jmt8345 wrote:
Any feeling on how the Attack/Force would pair up with Enve 6.7s? My "windtunnel eyeball" makes me think the Attack "looked" too narrow for that wider front rim. **disclaimer I a novice on this stuff**. Thanks,





Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
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Freelance sports & outdoors writer Kathryn Hunter
Quote Reply
Re: New Crr roller data [rruff] [ In reply to ]
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Thanks, like I indicated I am total aero novice so all input is apprecaited.
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Re: New Crr roller data [jackmott] [ In reply to ]
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And I'll bet they didn't turn the Attack backwards... should have helped the high-yaw numbers.
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Re: New Crr roller data [rruff] [ In reply to ]
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Funny I just ordered two GP4KS from wiggle as well as some latex tubes. Curious what you mean by installing right to not kill yourself. I've never ridden latex, well at least on a bike.

"Base training is bull shit" - desertdude
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Re: New Crr roller data [Grux] [ In reply to ]
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Just ordered a GP4000s from Amazon last week. Got it for 44.95 with free shipping. Had it in 3 days. I've seen them cheaper on some UK sites but the fast shipping sealed it for me.

Of note the description on the site was for a GP 4000s and I received the updated GP 4000s II. Not sure they're different except for some graphics.

Formerly DrD
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Re: New Crr roller data [thirstygreek] [ In reply to ]
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If you get tube pinched under the bead, instead of experiencing an immediate failure it can push the tire off a few hundred miles later.
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Re: New Crr roller data [rruff] [ In reply to ]
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Oh shit. Lots of powder and care I guess.

"Base training is bull shit" - desertdude
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Re: New Crr roller data [thirstygreek] [ In reply to ]
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they are colored tubes, so you can do your bead seat check on both sides of tires and if you don't see the latex tube, you are good. if you do, work it I such that you dont
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Re: New Crr roller data [jeffp] [ In reply to ]
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I am going to order the GP4000S today on Amazon. Looking forward to trying them out.
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Re: New Crr roller data [thirstygreek] [ In reply to ]
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I can't remember the last time I even needed to unpinch a tube during installation... been many years anyway.

Powder tire and tube both, wipe off excess.
Inflate tube just enough to hold shape.
Install one tire bead.
Stick valve in wheel and then the rest of tube... seat it fully and evenly onto the rim with no twists, stretches, or bulges.
Push valve away from rim tape a little and seat the next bead at that point.
Work the bead around both sides, ensuring that it is in the center of the rim bed. Pull it down with your hands to stretch it.
If you can't get the last bit on by hand and you are worried about pinching the tube with a lever, use a Koolstop Bead Jack.
Check for a pinched tube.
Press on tire at the valve to ensure that it is against the rim tape when you inflate. If you don't then the tube might wrap under itself at the valve.
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Re: New Crr roller data [GreatScott] [ In reply to ]
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GreatScott wrote:
How do wide rims affect your perspective on fat tires? For example, the 24.4mm Flo 60/90. Based on this and related threads, I was thinking the 22mm Attack and 24mm Force would be a nice fit. Now I'm thinking Attack/Attack or Atttack/GP 4000s.

Scott

rruff wrote:
On wide rims the clincher tires grow in width. The Force will be ~26mm wide on that rim, the Attack ~24mm.

Picked up some calipers today and measured the Force at 27mm and Attack at 25mm (twice). Both at 100 psi on a Flo 60/90. That Attack measurement surprised me as it is quite different than the 22mm spec.
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Re: New Crr roller data [GreatScott] [ In reply to ]
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GreatScott wrote:
GreatScott wrote:
How do wide rims affect your perspective on fat tires? For example, the 24.4mm Flo 60/90. Based on this and related threads, I was thinking the 22mm Attack and 24mm Force would be a nice fit. Now I'm thinking Attack/Attack or Atttack/GP 4000s.

Scott


rruff wrote:
On wide rims the clincher tires grow in width. The Force will be ~26mm wide on that rim, the Attack ~24mm.


Picked up some calipers today and measured the Force at 27mm and Attack at 25mm (twice). Both at 100 psi on a Flo 60/90. That Attack measurement surprised me as it is quite different than the 22mm spec.

That is because you are measuring on wide rim wheels versus a standard rim.


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