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Vittoria CS 25mm CRR test
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I just tested one of these new tires and here's what I got (with 2017 CS 23mm for comparison):

Width / Height / CRR
2017 CS 23mm / Latex tube / Jet 6+ rim / 100 psi: 25.8mm / 23.8mm / 0.00311
2018 CS 25mm / Latex tube / Jet 6+ rim / 100 psi: 28.0mm / 25.7mm / 0.00288
2018 CS 25mm / Latex tube / Jet 6+ rim / 90 psi: ______ / ______ / 0.00300

Some comments:

(1) This is probably about what you'd expect: a bit wider, a bit faster. It's not going to make or break anything, but it is the fastest tire I've ever tested. Given the extra width I wouldn't use it in front, but maybe in the rear.
(2) This tire was *way* easier to mount than the 2017 23mm on this rim. I easily mounted it with no tools. The 2017 23mm's required tools and technique to get on. Don't know if the 2018 23mm is any different.
(3) Yes I know I get higher CRRs than Tom A does. I'm not sure why that is but it is very consistent. Believe me I've tried to figure it out. You can disregard the absolute number if you want, but the differences are 100% repeatable - I do two runs on each tire and always get exactly the same answers.
Last edited by: lanierb: Mar 8, 18 20:48
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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Thanks for posting. So given that casing tension should probably be equalized to avoid impedance problems, I would think the 100psi/23 should be matched with the 90psi/25. So a Crr difference of about 0.0001. I don't remember my conversions, but isn't that about a watt at typical TT speeds?
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Re: Vittoria CS 25mm CRR test [grumpier.mike] [ In reply to ]
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grumpier.mike wrote:
Thanks for posting. So given that casing tension should probably be equalized to avoid impedance problems, I would think the 100psi/23 should be matched with the 90psi/25. So a Crr difference of about 0.0001. I don't remember my conversions, but isn't that about a watt at typical TT speeds?
Yeah it's worth about one watt at 25mph. It's a wider tire so presumably there's some aero cost. I wouldn't run it on the front. I'm not sure about the rear. The wider trailing edge could eat up that watt. Sometimes it's nice to have a wider tire though, like on bad roads.
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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I have not been able to get my hands on a 25mm one:(
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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Any chance you have the measured widths? Also, did you test with a tube or tubeless? The one thing that's always put me off about going tubeless on the Jet+ rims is how friggin hard it is to get the tire on/off.
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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Thanks for the info!
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Re: Vittoria CS 25mm CRR test [GreenPlease] [ In reply to ]
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GreenPlease wrote:
Any chance you have the measured widths? Also, did you test with a tube or tubeless? The one thing that's always put me off about going tubeless on the Jet+ rims is how friggin hard it is to get the tire on/off.
All that info was in the first post. It measured at 28.0mm on that rim, almost exactly 2mm wider than the 23s. Also, it was pretty easy to mount by hand even, no tools required. WAY easier than last year's 23s.
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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Thanks, good data!

Have you tried weighing the tires? I just received a 25mm version and it actually comes in at only 227g, which is less than the listed 240g. Interestingly this is 3-5g grams less than the 23mm tires I have from last year, which are listed at 225g (and were actually listed at 205g initially, but I think that was for the version without the coating to the sidewalls, which never saw wide release). My 25mm version is all black, whereas my 23mm versions from last year have the anthracite/grey sidewalls, FWIW.

It would be strange if the 23mm versions are heavier than the 25mm version, so my guess is the 2018 versions and/or the all black versions are lighter than the 2017 anthracite versions.
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Re: Vittoria CS 25mm CRR test [MTM] [ In reply to ]
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MTM wrote:
Have you tried weighing the tires? I just received a 25mm version and it actually comes in at only 227g, which is less than the listed 240g. Interestingly this is 3-5g grams less than the 23mm tires I have from last year, which are listed at 225g (and were actually listed at 205g initially, but I think that was for the version without the coating to the sidewalls, which never saw wide release). My 25mm version is all black, whereas my 23mm versions from last year have the anthracite/grey sidewalls, FWIW.

I found the same thing. Here are the weights from four tires:

2017 23mm Grey: 241g
201? 23mm Black: 235g (bought this year but could be 2017)
2018 25mm Black: 233g
2018 25mm Black: 226g

It seems weird that the 25s weigh less than the 23s.
Last edited by: lanierb: Mar 9, 18 18:23
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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Thanks for the weights. Strange indeed. Doesn't seem to be the sidewall colour that influences the weight then.
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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lanierb wrote:
MTM wrote:
Have you tried weighing the tires? I just received a 25mm version and it actually comes in at only 227g, which is less than the listed 240g. Interestingly this is 3-5g grams less than the 23mm tires I have from last year, which are listed at 225g (and were actually listed at 205g initially, but I think that was for the version without the coating to the sidewalls, which never saw wide release). My 25mm version is all black, whereas my 23mm versions from last year have the anthracite/grey sidewalls, FWIW.

I found the same thing. Here are the weights from four tires:

2017 23mm Grey: 241g
201? 23mm Black: 235g (bought this year but could be 2017)
2018 25mm Black: 233g
2018 25mm Black: 226g

It seems weird that the 25s weigh less than the 23s.

I guess the fact that it weighs even less indicates not, but do we have any reason to believe a 25c might be less flat prone? I've actually been thinking about switching out of my CS on my Dash disc back to a Conti GP TT.

Dimond Bikes Superfan
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Re: Vittoria CS 25mm CRR test [ericlambi] [ In reply to ]
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not running tubeless on the Dash?

Never got the 23 mm CS to work on mine tubeless, but hoping the 25 mm might. Currently has a 25 mm hutchinson galactic mounted tubeless.
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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lanierb wrote:
(3) Yes I know I get higher CRRs than Tom A does. I'm not sure why that is but it is very consistent. Believe me I've tried to figure it out. You can disregard the absolute number if you want, but the differences are 100% repeatable - I do two runs on each tire and always get exactly the same answers.

I can think of a couple of possibilities:

1) You're using different latex tubes. Michelins are faster than Vittorias and the smaller Michelin (18-20c) is faster than the bigger one (about half a watt, IIRC)

2) You may not be calculating weight on the rear wheel the same way. If one of you is off by a few pounds, that could account for the differences.

3) You may be centered on the rollers differently. I always carefully measure so that the lowest point of the wheel is precisely centered between the rollers. That means shifting the bike position for different-sized tires.

The good news is the consistency. I found that if I fudged the weight to make the Crr of one of my tires match Tom's (or Al Morrison's), all the others would match up almost exactly. It sounds like it's the same for you.

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Re: Vittoria CS 25mm CRR test [jens] [ In reply to ]
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jens wrote:
1) You're using different latex tubes. Michelins are faster than Vittorias and the smaller Michelin (18-20c) is faster than the bigger one (about half a watt, IIRC)

That's interesting, I don't remember having heard about differences between latex tubes. Have you tested other latex tubes than those? One would think that lighter tubes should be slightly faster (less material), though IIRC Michelin and Vittoria tubes are pretty much the same weight (70-80g).
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Re: Vittoria CS 25mm CRR test [jens] [ In reply to ]
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jens wrote:
lanierb wrote:

(3) Yes I know I get higher CRRs than Tom A does. I'm not sure why that is but it is very consistent. Believe me I've tried to figure it out. You can disregard the absolute number if you want, but the differences are 100% repeatable - I do two runs on each tire and always get exactly the same answers.


I can think of a couple of possibilities:

1) You're using different latex tubes. Michelins are faster than Vittorias and the smaller Michelin (18-20c) is faster than the bigger one (about half a watt, IIRC)

2) You may not be calculating weight on the rear wheel the same way. If one of you is off by a few pounds, that could account for the differences.

3) You may be centered on the rollers differently. I always carefully measure so that the lowest point of the wheel is precisely centered between the rollers. That means shifting the bike position for different-sized tires.

The good news is the consistency. I found that if I fudged the weight to make the Crr of one of my tires match Tom's (or Al Morrison's), all the others would match up almost exactly. It sounds like it's the same for you.
Thanks Jens! I will test the Michelins. I've been using the Vittorias.

I actually suspect that the answer may be 2. The scale I use to measure rear load is one of those digital ones that locks in the weight after a few seconds and I can't really get fully settled in that time. The rear load I get makes sense (about 60% of the total load), but it could still be wrong, so I'm going to try to find another scale and see if that changes.
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Re: Vittoria CS 25mm CRR test [jens] [ In reply to ]
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What makes Michelin tubes faster than Vittoria?

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Re: Vittoria CS 25mm CRR test [BryanD] [ In reply to ]
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BryanD wrote:
What makes Michelin tubes faster than Vittoria?

I don't know. I should also qualify: I tested that a very long time ago and haven't re-tested since then. So things might have changed. At the time, Al Morrison confirmed my finding that using an under-sized Michelin (the 18-20C) was the fastest option with any tire -- something like half a watt difference from the Michelin 22-23C. Of course the problem with any Michelin is the lack of removable valve cores. That's why I use Vittorias now.

My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
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Re: Vittoria CS 25mm CRR test [jens] [ In reply to ]
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jens wrote:
BryanD wrote:
What makes Michelin tubes faster than Vittoria?


I don't know. I should also qualify: I tested that a very long time ago and haven't re-tested since then. So things might have changed. At the time, Al Morrison confirmed my finding that using an under-sized Michelin (the 18-20C) was the fastest option with any tire -- something like half a watt difference from the Michelin 22-23C. Of course the problem with any Michelin is the lack of removable valve cores. That's why I use Vittorias now.

interesting. michelins are bigger as i recall. and i don't think they have removable valve cores. i always thought michelins were probably not as good. and i'd be shocked if vittoria wasn't making the michelins. i guess i was wrong.

Dan Empfield
aka Slowman
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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lanierb wrote:
Sometimes it's nice to have a wider tire though, like on bad roads.

After vibrating my way through a 70.3 I moved to 25's & dropped pressures to 80/85, ride's been miles better since.

But I've been wondering if that's mainly pressure related & if 23's (that measure ~25) at 80/85 would be faster & still comfortable.

Main concern is pinch flats, not sure if this odd mark I found post-puncture (leak in the top corner) was caused by a pinch, but I'd really rather avoid rim-riding again..



Can you run 25 pressures on 23 tires that measure 25?
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Re: Vittoria CS 25mm CRR test [SteveM] [ In reply to ]
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I'm 160#'s and run my 23 corsa speeds at 70psi. Hed belgium wheels. I think they came with a label stating not to exceed 85 psi.
Cheers
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Re: Vittoria CS 25mm CRR test [lanierb] [ In reply to ]
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Are you using the same drum diameter rollers? Smaller diameter should lead to higher measured Crr.
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Re: Vittoria CS 25mm CRR test [carlosflanders] [ In reply to ]
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carlosflanders wrote:
Are you using the same drum diameter rollers? Smaller diameter should lead to higher measured Crr.
Yes I have the roller diameter factored in.
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Re: Vittoria CS 25mm CRR test [SteveM] [ In reply to ]
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SteveM wrote:
But I've been wondering if that's mainly pressure related & if 23's (that measure ~25) at 80/85 would be faster & still comfortable.

25mm and 23mm will both have the same spring rate at 80-85psi. Thank you Josh Poertner! And I think I've seen Damon Rinard mention this as well.

Pinch flats are a consideration, though latex is very difficult to pinch. Rim damage is a consideration. Last but not least there is a Crr vs aero tradeoff. Probably worth going big on the rear, but not the front.
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Re: Vittoria CS 25mm CRR test [jakesdk] [ In reply to ]
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jakesdk wrote:
not running tubeless on the Dash?

Never got the 23 mm CS to work on mine tubeless, but hoping the 25 mm might. Currently has a 25 mm hutchinson galactic mounted tubeless.

I am running tubeless with the CS. I did not set it up myself, bike mechanic did it. it took two of them, it didn't look easy.

Dimond Bikes Superfan
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Re: Vittoria CS 25mm CRR test [rruff] [ In reply to ]
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Your welcome! Glad our numbers are helping people out!

Also, on the Michelin and Vredestein latex, we found that smaller section tubes will yield slightly lower Crr with the theory being that they are thinner when inflated.. and since the Vredestein ones are thinner to begin with and smaller in section..they are slightly faster still. The downside, however, is that the more over-stretched the tube is, the more it becomes susceptible to heat failure as well as both pinch and puncture type flatting..which makes sense as there is just far more stress/strain in the overinflated tube. So while there may be fractions of a watt to be found, in using thinner or undersized latex tubes, the risks are most likely not worth it.

We were using the Vredestein's in Tony Martin's wheels when he double flatted at the Tour in 2012, the combination of undersized, overstretched and already extremely thin tube made the setup overly prone to punctures, and we saw both puncture and heat flats in those early runs and moved onto Vittoria tubes after that.

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