IME, they are every bit as durable as the Zipps, and surprisingly long-wearing as well.

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http://bikeblather.blogspot.com/

Where did you buy them from? I've been looking to get some my race in 6 weeks.

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blog

I don't have them yet. My local shop put in an order. I have no idea when they will get here

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I've got the 24mm Turbo Cottons on order but should I be looking at something else?

FYI. Every aero test I've seen on "open tubulars" shows poor performance. TCs too.

If there was enough of a Crr benefit to overcome this, then maybe they'd be a good choice for racing. But we can get tires that have low Crr and good aero properties, both.

Does anyone run the tubeless versions?

Tubeless Turbo Cotton?

I haven't been on tubeless tires in several years.

I'm using the tubular version , don't find em significant faster (just by feel btw) than the conti competition or veloflex Carbon but they wear out damn fast. Don't think to extend the 1000 km.

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-shoki

I am very eager to see rolling resistance + aero test on this tire, but suspect it won't come out ahead. The 22mm SWorks turbo looks good though.

Where have you seen aero tests of the turbo cottons? I would love to check that out.

They make a tubeless S Works (not turbo cotton) but the TPI of the casing is pretty darn high for a tubeless tire. 180 or 220tpi.

You say that like you think it would be a bad thing.

So your conclusion is front and rear Turbo Cotton for 2016? Let the tire debate begin! Rapp said use the Turbo Cotton if i remember correct from last yrs threads, others said Conti SS but no definitive tests if i remember correct. Is anyone coming out with new tires in 2016? As of now i have 2 conti TT and 1 Turbo Cotton to mix and match.

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2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

this has already been done.

Edit: adding some commentary to explain what I *think* these charts mean

work by Tom A. at www.bikeblather.blogspot.com

1) Interesting chart showing that a) the Roval CLX 64 w/ Turbo 22mm is a very competitive wheel, and that the HED Jet 6+ is comparable with same tire, and b) the 24.25mm wide TC is about 2.5 watts slower than the Turbo 22mm, tracking with my SWAG ROT that 1mm = 1 aero watt in tire width. Also confirms what we already know about vulcanized vs. open tubular tire designs at wide yaw angles.



2) OTOH here you have data showing the TC 24mm is equal to another tire, the so-called aero gold standard GP4000s 23mm at zero yaw. Also interesting is that the Turbo 24mm is slightly faster, leading me to believe that the Turbo series of tires have some magic aero properties that their Turbo Cotton "open tubular", a known poor performing design with regard to aero, does not have.



That said, the tire is a system, with both aero and Crr (and watts to spin, another story). This chart shows how good the Turbo Cotton 24mm tire really is with Crr data overlaid. The 24mm Turbo Cotton loses a watt or two from aero penalties, but gains 5 watts back at 40kph and 7 watts back at 50kph.



4) finally we have a chart depicting aero, Crr, and weighted yaw angles based on Mavic testing showing that at pretty much all speeds, the Turbo Cotton 24mm is fastest as compared to the "gold standard" GP4000s 23mm.



All this, combined with the knowledge that GP4000s 23mm = Turbo 24mm < Turbo 22mm in aero (first + second charts) and likely same in Crr (Tom A.'s Crr charts), leads me to believe that there's never really a good reason to run the GP4000s 23mm anymore. Same conclusion when you process Zipp's data that 22mm Attack > 23mm GP4000s > 25mm GP4000s in aero, and also Tom A.'s data that shows the GP SS 23mm is not too bad aero wise and VERY fast Crr wise.

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"Feel" is highly unreliable re tire rolling resistance. I do my own roller testing, and I find that my subjective impression of a relatively slow tire seems to be reasonably borne out by my testing, but I have very little ability to differentiate between tires by feel once they get to a moderately high level of performance.

I have a set of the S-works Turbo Road Tubeless (the only Specialized tubeless offerings I'm aware of). I love tubeless ('cuz I have a lot of really crappy chip and seal roads and I feel more comfortable running tubeless at lower pressures than I would a tubed tire) and I was not dissatisfied with my usual favorite tubeless tire, the IRC Pro Tubeless Lite. I just decided to give the Specialized tires a try after reading a good review and, go figure, they're IRC Pro Tubeless Lites with a file-type tread pattern added. They're nice tires that seem to roll well, last a long time and can take a lot of abuse (I don't hesitate to ride crappy road shoulders full of debris or to go down a gravel road here or there).

I wouldn't use them as my go-to race tires on a smooth, 40k TT course. But I've done Beach 2 Battleship a few times and there's a lot of marginal chip and seal and other iffy pavement on that course and these might be a good choice -- keep the psi low and keep the body fresher for the run.

I believe it was already touched on in another thread but Vitorria has the new Graphine tires (23mm) that are rumored to be as fast or faster than the TCs, handle better AND have far better puncture protection.

All speculation though, haven't seen a single review.

I came across this on the train to work today: http://www.bicyclerollingresistance.com/...-corsa-graphene-2016.

This test has them on par with the GP4000s. They look pretty, so that's worth something!

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/kj

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I have the corsa graphene tires in 25c on my road bike right now with latex tubes. Very nice tire. These aren't the corsa speed tires that should test similar to the turbo cotton in rolling resistance.

If the speed model has similar construction as the corsa, I don't think it will be an aero winner. There is a distinct lip from the tread to the casing.

From the looks of the charts posted the turbo cotton loses in aero more than it gain in crr.

Looks like I will be using the sWorks turbos in 24/22 this year.

I think the S-Works Turbos find a great balance. I am running them 24/26 on my road bike and am a big fan.

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/kj

http://kjmcawesome.tumblr.com/

Must have missed that thread! To good to be true! When is it coming out so i can buy it :-)

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2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

GP4000s are like 7 watts per pair slower that turbo cottons. That website is not the best source of info

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Not at all! It's an awesome thing!

I am going to put those on my gravel grinder. Look like awesome tubeless tires.

Great durability I use them and think they're great but I might try supersonics this year I know those are super fast

so you would run the SS over the Cotton?

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2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

but isn't TC a bit wider? aren't u losing some cause the tire is not as aerodynamic?

just asking...

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

despite being a 23 the GP4000s 23mm is actually like 24.5mm wide, same or wider than the TC which is classified as a 24mm.

But generally, I think as a rule of thumb you can assume a tire loses 1 aero watt/mm in width, but gains a certain number of watts back in better Crr for a wider tire.

There's enough data however on Tour Mag testing and Tom A.'s Bike Blather blog to compare aero and Crr for most tires, and the fact is that the very best rolling tires, at the speeds we ride them at, are faster than the so-called aero tires.

That said, the GP4000s is best for VERY windy days or slow riders, and is also a very good all-round tire. So are the Turbo 22mm and 24mm tires.

Scroll up at the charts I linked to to see what I mean.

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thx :D

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

but isn't TC a bit wider? aren't u losing some cause the tire is not as aerodynamic?

It's not even the width.

All "open tubulars" that I'm aware of have a step where the tread attaches to the casing. Apparently this is enough to screw up aero performance a lot. Every one I've seen data on does poorly. That includes the TC. Specialized and Tom A tested the TC recently, Coggan's test of the Veloflex Record, Flo's test of the Vittoria Tri, John Cobb's remark over a decade ago that open tubulars cost a lot of watts aerodynamically, etc.

Maybe as a rear tire it would be ok. But even then a Force would be more aero and puncture resistant, and nearly as good for Crr.

this is my logic too, as I am the owner of the fast rolling Force and the "magic" Attack, but I'm not sure we've cracked the code yet on consistency of Conti tires. If you factor in the differing results Tom has gotten, perhaps from different "lots", then the TC makes sense, especially if you're riding at 40kph or so. Posting this for reference from the Graphene thread... even Conti has 22mm Attacks as slow:



OTOH, there is interesting data from Tom that shows the 23mm GP SS to be an OK front tire, on certain wheels anyway, and some data from Josh@Zipp that shows the trivial amount of aero loss on a rear shielded wheel. I know this is only one test.



Having said that, there are some that can't run "tall" tires for whatever reason. This is true for me on my road bike, an old S5. With my TriRig front brake at perfect height, a 23mm GP4000s rubs the underside slightly, and that and a 24mm Force rub the rear cutout like crazy. For that reason I ride the 24mm TCs for road racing, which are the best handling tires I've ridden and roll fast.

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I would never pick a GP4000 for racing, and a 23mm SS is faster and smaller than a TC.

Now that I built a 23mm rim into my Powertap, anything bigger than a 20mm SS is in danger of rubbing the chainstays (2005 Trek TTT). Doh! Not sure that was a wise decision, with all the rough chipseal courses around here...

I agree, but don't have enough time on the GP SS 23mm to comment.

Have you seen or heard any durability comparisons between the TC and SS?

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I have lots of experience on the SS, mostly 20. It seems that the new 23mm SS has thicker tread or something because they are heavier than the ones I've got which are ~145-150g. The 20s are ~130g.

But anyway, they seem to be decent against punctures even without a kevlar belt, but tread is thin so they don't last long. Maybe 500 miles on the rear, but lots more on the front. They are for racing only, at least on the back. The Attack, Force, and GP TT have thin tread also, but thicker than the SS.

I have a magic Attack, too. Actually 3 of the 4 I tested were better rolling than any GP4000, but one was oddly poor. It wasn't heavy either. No idea what would cause that. All 3 Force tires have been good, but they are too fat for me to use on the TT bike, even before I put a wider rim on.

One thing I've been curious about is potential differences in tire "scrubbing" losses. I've noticed when climbing hills that the GP4000 and Force on the rear make more noise than a Vittoria or Veloflex. It sounds like scrubbing... not sure how to describe it. So far I haven't gotten ambitious enough to see if I can detect a difference in testing. If anything it would be high-torque related (that's when I hear it), so I'd need to do climbing tests. Several hours of tedium. Torque is very low on rollers.

Where do you get your TCs? I didn't think they had been publicly released.

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Specialized Turbo Cotton 24mm? From their website and also eBay

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Besides directly ordering from the Specialized website, any Specialized dealer should be able to order them if they don't have them on hand.

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http://bikeblather.blogspot.com/

This is what I see when I go to Specialized's website. What am I missing here?

---

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Don't know.... Out of stock?

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My shop just got a shipment. I think they were out of stock for a while, but stock is showing up now.

My lbs has them in stock in both 24 and 26.

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/kj

http://kjmcawesome.tumblr.com/

interesting, AndyF has a theory about that when riding in crosswinds... majority of people lean the bike into the wind but his hypothesis is that if you keep the bike straight and just lean the body there is significant Crr savings to be had.

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Hey guys I've been following this thread and I'm having trouble deciphering what the conclusions are here. Maybe I am thick, or maybe it just hasn't been spelled out clear enough. What is the fastest 1 day race set for a non-wide profile pair of wheels? I've got 2013 Reynolds Strike C (66mm) and Assault C (46mm) wheelset and I'm looking at some marginal gains for the race season. Figured tires were a good starting point and these will be combined with latex tubes.

1. Conti Grand Prix (Attack Force) 22/24
2. Conti GP4000S II 23C
3. Conti GP4000S II 25C
4. Specialized Turbo Cotton 24C
5. Specialized S- Works Turbo 24C
6. Zipp Tangent Speed 23C
7. Zipp Tangent Speed 25C
8. Vittoria Coursa Speed (Open TLR) 23C
9. Conti Grand Prix TT 23C

I'd like something that is not going to be super frail but also I'm only going to put a total of 350-600KM on the set of tires. Any help would be appreciated :)

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"Train so you have no regrets @ the finish line"

23mm SuperSonic. They are not "super frail." And if you want measurable gains, that's the obvious choice.

Of your list I'd go with 1) or 6).

It's a tradeoff between aerodynamics, rolling resistance, durability, puncture resistance, etc. And all of these values are variable and uncertain to boot.

All "open tubulars" suck for aero, so I'd completely remove them from consideration for the front. Maybe the lowest Crr ones can be viable for the rear. In your list, 4, 6, 7, and 8 are open tubulars. GP4000 is a training tire with thick tread. I don't care that it has "magic" aero properties sometimes.

If your rims are narrow like <22mm wide then the 20mm SS is probably best on the front. It would probably be best on the rear also. If you want more puncture protection and a little more cushion, I'd recommend the Attack turned backward. The SS23, TC, Force, Vittoria, Zipps, and GPTT are all viable on the rear, too. Aero is less important there. The GPTT, Force, and Attack are best for puncture and cut resistance.

Thanks so much guys ... I appreciate the insights. I was reading over a ton of literature but keeping current isn't as easy as it should be.

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"Train so you have no regrets @ the finish line"

conti GP TT might be an option as well, depending on verification of Conti's Crr testing.

and a "magic" Attack on the front might be a wash with the SS as well. They mate very well with the narrower HED Jets

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What does Conti's GPTT testing say? Did they compare to an SS?

Conti tires (the good ones) all have the same casing and probably the same tread compound. All but the SS have the vectran belt. The variation is size, tread pattern, and tread thickness.

Based on reports of the GPTT being fat it's basically the same size as the Force, though with slicker and probably a little thinner tread. Maybe the same tread thickness as the SS. But the SS23 is smaller even though they are both 23, and doesn't have a vectran belt. And the tread on the Force might help in high yaw aero. That's about it.

Wait a second. I thought that the graphs above showed that the Turbo Cotton had the lowest combination of aero AND crr. Am I missing something?

My understanding is that the GPTT will be slightly slower than the SS but the upside is you get the Vectran belt and it's better for handling.

I've noticed there are two different categories of people on these threads: the ones who care more about aero and the ones who care more about crr. I do think everyone understands there has to be a common ground that makes everyone happy but it appears apparent you're one or the other until there is a very definitive answer. I think that is why some can't understand what tire is "the best" for racing.

No, it's 3rd in Crr (though very close to 1st).

And it's not in the bottom graph. That's the SWorks Turbo <period>. Not the Turbo Cotton.

Edit: This is Tom's graph where the Turbo Cotton looks brutal, aero-wise. Granted it's going against 22mm tires. But still.

Look at Tom A's recent testing at Specialized. I think the graph is in this thread.

But that is just aero. I had said aero plus crr.

scroll up for the Tour Mag chart that used Conti's own rollers, but the GP TT compared the same with the TC on the same roller, which compares the same to the SS 23 on Tom A's roller.

at this point I'm not at all concerned with high yaw, which was the red herring that got everyone all excited about the GP4000s 23mm. I've done well with magic attack backwards front and rear, Attack Force front and rear, and also TC 24mm front and rear.

Any of these will do well IMO, unless you're at TT nationals or something and then you actually have to sit down and do the math. In which case I really like the 23mm SS aero data from Tom A's blog as well as the top of class Crr

Grain of salt, all of my info is taken from other sources and then extrapolated with reasonable amount of informed opinion

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THIS. All of it.

the take-away is that Crr more than makes up for any aero sins.

and, the faster you go, the lower the yaw angles, and the higher the penalty for bad Crr tires.

so yes, in a lot of situations, the TC is very good, at least compared to the most aero tires. That said, there are other tires just as fast rolling that might be more aero because they're vulcanized and not open tubular like the TC. The SS 23mm is one of these and had reasonably good aero numbers when Tom A. tested in the Specialized tunnel. The GP TT 23mm might be another. Zipp's best and narrowest offering might be a third. A "magic" Attack 22mm backwards might be a fourth.

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I just saw that by looking at the CRR spreadsheet and the aero spreadsheet it looks like the supersonic is the best combination of aero and rolling resistance. It looks like the attack is similar to the TC.

The problem that I have heard is that the supersonics are very fragile. I have yet to ride an Ironman race in the US that I would feel very comfortable with a fragile tire. Although a ~4 watt total benefit in aero plus CRR would be damn tempting.

Right. But if you go over to the aero data spreadsheet and look at the Watts @ 50kph.

It's a little hard to compare/graph directly, since he only used the HED Jet6+ for two tires. But you can do some speculative analysis. The 22mm SW Turbo kicks the shit out of the Turbo Cotton on aero on the Jet6+. The Supersonic beats the 22m SW Turbo on the Flo9. The 22mm Attack (narrowly) beats the 22mm SW Turbo on the Flo9.

And then look at the Crr spreadsheet and the power for two tires at 50kph, you can get a pretty good idea that things aren't going to end well for the Turbo Cotton. You can create some rough graphs using the data from the two spreadsheets.

Just my two cents. I have ~500 race miles on two pairs of Supersonic, with some relatively rough chipseal, etc. Even hit a few potholes. No flats. No cuts in my tires.

Run them with a few ounces of sealant in latex tubes, and you're going to have a very fast, fairly reliable set of race tires.

The SS23 has great aero and Crr.

It depends on what which tests and charts you want to give priority to. I guess there was some chart floating around that said the TC 24 had good aero properties, but I was skeptical at the time, and now that we have other data (from Specialized's testing) that show it does poorly, that's what I believe. Like I said earlier "open tubulars" traditionally do not do well aerodynamically. They have a squat profile and a lip on the side of the tire that apparently messes with airflow.

Crr isn't a definite number either. Samples vary, and for us guys doing roller testing there can be fairly large error bars as well. And then there are those who claim roller testing is a poor representation of what happens on the road, with roughness, vibration losses, etc. It's one of those things that is difficult to prove.

I haven't tested a TC, but it's a Vittoria Corsa casing, with a modified tread. I have tested a lot of Vittorias, and though they are good, they consistently fall short of the SS23. Based on the testing I've seen compared to what I've done, and scaling and extrapolating the numbers, I'd put the TC24 at about the same Crr as the SS23. I don't know of anyone who has tested them both other than Tom.

It's viable as a rear tire (where aero doesn't matter as much, and Crr matters a little more), but I wouldn't put it on the front.

BTW, this is all hair splitting stuff for those of us who like to split hairs.

Thanks. I appreciate you guys going through the thought process.

You say splitting hairs and are right but something like 3-4 watt difference adds up to minutes (2-3 ish I think) on an Ironman course. In the 35-44 AGs there is often a number of guys in that window right at the bubble for Kona. Split enough hairs and it could mean the difference between going to the big island and not.

The problem that I have heard is that the supersonics are very fragile. I have yet to ride an Ironman race in the US that I would feel very comfortable with a fragile tire. Although a ~4 watt total benefit in aero plus CRR would be damn tempting.

I started using them for TTs 8 years or so ago. They aren't fragile. They won't be as puncture resistant as one of the Contis with a vectran belt, but I think they are pretty close in that respect compared to Vittoria (who make the TC also). The tread compound also seems to be very resistant to cutting like all the Conti tires. The tread is very thin, so they won't last long, and you definitely want to avoid skidding them. Use newish ones for important races.

When you race, do you ride on the shoulder? If you aren't required to, I wouldn't. That's where all the wires, glass, nails, and gravel accumulate. Vehicles keep the road pretty clear starting at the white line.

I think you overestimate the aero penalty of the TC. Looks to me to be 2.5 watts according to Tom A. At 50kph you're getting back 3.5 in Crr. You'll never see those yaw angles where it really makes a difference.

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Should I cancel my order then?

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I probably overstated it. But I do see some pretty steep yaw angles on my home TT course, even averaging ~28MPH.

6 and 7 are the Zipp tires. The "open tubular" designation, if I understand it, has to do with the manufacturing process, vulcanized vs handmade. I have both the Zipp & Vittoria tires. The Vittoria tires do indeed have a definite ridge on the side of the tire where the tread meets the sidewall, and it's presumably this ridge that leads to their relatively poor aero performance. Zipp tires look nothing like the Vittorias, they visually look much more like the Contis, the transition between the tread and sidewall is seamless, there's a tiny line but it's not a raised ridge like the Vittorias. The Zipps do have a very light diagonal siping pattern somewhat like the GP4000s but not as deep. In the hand they feel just as supple as the Vittorias, unlike Contis which have always felt stiffer.

I test tires on the rollers and the Zipps tested very fast, on par with my control tire, a Vittoria triathlon. They certainly look much more aero than the Vittorias. I also do field testing but have never tried to test tires, thought it might be too granular to test using VE but might give it a try this spring for laughs. I raced on a Zipp speed 23/25 combination last season and at least my subjective impression is that they are very fast tires in the real world for whatever that's worth. I've also gotten inconsistent rolling resistance results from the Conti tires I've tested, I'd never use one for racing without testing to make sure it was fast.

Bottom line is I think that assuming the Zipps have poor aero performance similar to the Vittorias is a very dubious assumption.

I thought the Zipps were based on the Corsa like the old Tangente, but I see that they use the vulcanized 220tpi Diamante casing. Not an "open tubular" then.

Heck while we are at it, why hasn't anyone tested the Vittoria Pro Pista? It's very light at 150g in 23mm and has the same casing it seems: http://www.vittoria.com/.../diamante-pro-pista/

And after looking around the Vittoria site, I'm confused about graphene. If it really makes the tread *faster* then why is it used on the Rubino, but not on any track tires? Too low volume to bother? Or maybe the only thing thing making the Corsa Speed fast is thin tread. They have the heavier duty Corsa for people who want some longevity.

Aren't these Corsa graphene tests of the standard Corsa tire, not the Corsa Speed one?

Which tests?

rruff wrote:

Which tests?

The linked one: http://www.bicyclerollingresistance.com/...-corsa-graphene-2016
And this one: http://bikeboard.at/...-Welt-Pt.-2-th217501

I did find this update to the original testing by another guy but the language barrier makes it hard to assess the methodology: http://cyclesetforme.blogspot.co.uk/...raphene-reviews.html

Thanks, I hadn't seen the last link. Looks like a good recommendation for the Corsa Speeds.

He tested on rollers and on a climb. On the rollers he takes the measured power difference and divides by 4 to scale it to the road. He found the Corsa Speed to be substantially faster than the GPTT. About 10% lower Crr for the clincher.

Your 2nd link is a good example of variability, even with the same tires on purpose-built lab equipment. The differences between the results at Conti vs Specialized look pretty huge for those of us that like to split hairs.

Just wanted to confirm the width I found they were measuring out to a maximum width of 20.8mm and a rim depth of 66mm and the others 46mm depth. I've ordered a pair of GPTT and a SS 20c. Would either of these tires give away handling, wet weather reliable?

Thanks again

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"Train so you have no regrets @ the finish line"

Handling and wet would be fine. SS20 on the front. Is one of those a rear wheel?

Yeah I got two for the rear and one up front and before anybody asks ... no I don't own a tricycle lol I was going to go 2XGPTT but when I saw the width I got the SS in addition.

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"Train so you have no regrets @ the finish line"

quick one do SS23 and GPTT 23mm also measure more like 25mm similar to GP4000SII ?

The SS23 is smaller. I've heard the GPTT is pretty fat.

noone is worried about the bad aero properties of GP TT 23 - swissside article 13

I am actually wondering whether not to run Conti FORCE on the front (since i have zipp 808 so wider tires) and Tubo Cotton on the back?

any views?

Kinda fat for the front, IMO. But not a bad choice if you want some puncture resistance.

I forgot about that SwissSide aero test on the GPTT.

Just looked at the article.
Am I right in thinking the GP is like the supersonic?
So a 23mm supersonic would be a good front option?

the GP was good, the GP TT was not good

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So don't run the GP TT on front? Does the aero benefit (or lack thereof) matter more for the front then the rear? If so, if your running 808 and Sub-9 both wider wheels would it make sense to run a TT or most "aero" tire on the front and look at SW TC or Cont TT on the rear?

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Best thread on here in a long time keep it going! Ive been liking Force/latex tubes F&R on my road bike for some time, rolls fast, comfy and no flats

On the front I'd definitely use an narrower, aero tire. For drag and cross-wind stability, both.

The rear wheel being in a drafting position makes it less sensitive to tire width. On the rear there is usually more weight, making Crr more important.

So a 20mm supersonic, even on a wide rim?

I am trying to back into your 2.5W figure from the chart referenced.

The Hed Jet 6+ with TC 24mm looks to come in at 0.025 M^2, while the same wheel with the SW Turbo 22m is 0.018 m^2. The difference being 0.007 M^2. Using the rule of thumb formula below, doesn't this make the 22mm Turbo 7 watts faster at 30mph?

0.1 lbs (50 g) of drag (at 30 mph) = 0.5 s/km = 5 W = 0.005 m^2 CdA = 0.0005 Crr

Now, I don't go 30mph, and I know that drag is not linear, but it seems like the 22mm Turbo has a great deal of aero benefit as compared to the TC 24mm.

Am I missing something or doing the calc wrong?

Now, the TC24 may be overall faster. We have to take down the aero drag for speed, while probably increasing the CRR differences due to road surfaces. I haven't seen roller tests of the SW Turbo TT 22mm tire, but if you look at the spread between the 24 and 26mm versions of this tire you might be able to back into an estimate of CRR. Back of the napkin this looks to give the edge to the 22mm tire if you go 30mph, and if your surface is super smooth. If you are slower, and if the roads are less than perfect, it seems that the 24mm TC takes the overall lead.

.0205 not .025

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Unless the Crr is so good on the TT, or the yaw angles are guaranteed to be low

Otherwise use GP SS 23mm

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No. 20mm SS tests slower than 23mm GP4000s at zero yaw

The tire to use is probably the 23mm SS. Top of chart Crr and not bad aero.

Or, a "magic" attack backwards if you can get one. Same Crr as SS 23mm and same aero as GP4000s

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But the article above seems to suggest the gp4000 isn't aero, or am I reading it wrong?

Which tyre is the GP? Is it the supersonic! Confusing!

How can I tell I have one of those magic attacks? Should it always be mounted backward whether or not it's magic? I'm currently running 4000sII but have an attack and a SS on order, both in clincher for my 808FC.

I have a sub9 disc tubular in the back which has a 22mm conti sprinter. Should I just go for the lowest crr with puncture protection or what would be recommended? I have a seat tube so I'm thinking aero is not top of the priority. TC in the back?

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TC or Force

Always backwards Attack

Have to roller test the Crr to know for sure

GP4000s only beneficial at high yaw, i.e. slow riding or Kona. Does not roll that well

SS 23mm probably best for front.

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which article?

the thing about the GP4000s 23mm is that it's aero *at yaw*, a condition most fast TT'ers and triathletes don't see that much, and the other thing is that it doesn't roll as well as the fastest rolling tires, and when you do the math the less aero tires come out ahead because of their greater Crr savings.

GP SS 20mm - OK aero and OK Crr, best for H3 wheels
GP SS 23mm - very good Crr without a puncture belt, OK aero, probably best front tire for wide wheels
GP TT 23mm - very good Crr with a puncture belt
GP 23mm - a very good aero tire
GP 4000s 23mm - very good aero, OK Crr
GP 4000 23mm - more durable version of the 4000s
GP 4-season - even more durable version I would imagine
GP Attack 22mm - very good aero, very good Crr if you can find a "magic" one, puncture belt
GP Force 24mm - very good Crr, puncture belt, great rear tire

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My front rim is <17mm internal and 26mm at the tracks, so a SS23 is only ~23.5mm wide. I would stay below the width of the brake tracks on the front, if possible.

Still, a 20mm SS will be more aero (particularly at high yaw) so it's a tradeoff between that and Crr and potholes. I used SS20 on this rim last year.

20mm SS tests slower than 23mm GP4000s at zero yaw

Where have you seen that?

James Haycraft's data at A2 on Jack Mott's website

https://docs.google.com/...On560/htmlview?pli=1

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I dunno.... Based on Tom A's testing I think the SS 23mm might have the aero to overcome the 20mm poor Crr, especially after what James Haycraft found

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Without repeats and error bars I'm kinda skeptical. Very, actually. I've heard from a few fast riders who do WT testing that narrow is substantially better for aero, even on a wide rim.

There are other good reasons to use a bigger tire though besides Crr, if your roads are a mess.

nice summery, thank you! Were would you put the Sworks TC in there?

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That list wasn't a ranking BTW

The TC is very good.

Check out Tom's Crr chart at bikeblather.blogspot.com

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no i know, but nice to see just laid out like that! I need a chart of yaw, wheel and tire, and what to run then! If anyone wants a weekend project! lol. Will check out the article thanks :-)

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This is true. For me though, josh at zipp's advice about the penalties of over inflating vs. the benefits of under inflating plus my weight and chosen discipline (IM) on average roads leads me to wider tires, especially since I am the owner of a magic attack, fast force, and fast SS 23mm

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Did what I had time to do, sorry.

Can these riders you mention produce data? I know JeffP has data, but his is w/ a Zipp firecrest rim.

I know one used a Jet9. That wasn't WT though, that was field testing, which he does a lot.

How wide are those tires compared to your brake track?

James is that a 20mm? Looks wide like a 23mm, but I know the data Jack linked to listed it as a 20mm.

thanks for chiming in.

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The SS is a 20 and the GP4k is a 23

okay guys - can someone explain to me the "magic" attack - sorry missed it somewhere

i am in a bit of a quandary because I am doing South Africa - they changed the course so all of the bike is on the coastal road which means
- significant wind and very possible high yaw
- road surface is gnarly

- for the back it will be either TC 26 or GPTT 23/25 but for the front at those wind conditions and bouncy surface it is a problem - SS23 i feel may succumb to the road surface; i thought GP TT wd be it with its fat 23 but the aero data is damning at high yaw, then attack - the 22 seems its too narrow

that is why looking for best tire that would still provide some puncture protection and some comfort (i still remember the chipseal of IMNZ!)

If yaw and durability are of concern, IMO, the Attack is a pretty tough choice to beat.

Puncture protection won't help you with chipseal and roughness. The vectran belt is for thorns, wires, glass, etc. If you stay in the traffic lane and off the shoulder, the need for puncture protection is greatly reduced.

Some Attacks have tested very well. Nearly as good as SS23. Others not so good.

wdnt 22mm be of an issue of a chipseal road?

I took some measurements of a 20ss and a 23 ss on a jet+ wheel. values in mm

Wheel Tire Width Height
6+ 20 23.1 18.1 90psi
6+ 23 24.9 20.0 90psi
6+ 23 26.6 22.5 4000s 90psi
H3 20 19.7 16.8 110psi

Thanks, Jeff. Wow. I guess the inner width must be wide, and the tubeless shape sticks the tire beads right on the outer edge. Doesn't seem ideal, but the Jets (+) test well, I guess.

21mm per HED with 25mm track

edit: not positive 20mm tire is a good idea on these rims

The two I've had have measured a bit wide at right around 23mm. IMO it's tough enough. Certainly tougher than a supersonic. If you want something a bit tougher and cushier the 23mm GP4000s II is a good choice. That's a tire that seems to perform well consistently at yaw.

it's probably not. James Haycraft found that the 23mm GP4000s was *better* than the 20mm SS at zero yaw and Tom A. found that the SS 23mm was very good, better than a 22mm Attack or 22mm Turbo on a Flo 9, so with the Crr differences I'm going with the 23mm SS

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my thought was more along the lines of will the tire stay on under stress, not crr and aero.

I have seen vastly different results with certain tires in different bikes wrt aero such that I would never trust wheel alone data(which James' data was not) but it was on a different bike

Damn, how bad are these roads? Maybe the course calls for one of these?

I'd be concerned with amount of bead under hook on the 20SS, ie is it sufficient

I've seen loose tires fall off a rim before

it is probably fine, but I don't like being my own guinea pig

when has the tipping point been reached...http://www.slowtwitch.com/..._Rim_Width_2803.html

I tried the 20mm supersonic on a fc808 and never got comfortable that is was a solid fit. Probablu all in my head, but I was always nervous cornering on that setup.

I was never concerned with that set up, have ridden 20ss on both 808fc and super9 in past.

20ss snapped into place on jet+ rims just as 23ss and 4000s did. just not sure when it is too much

Can anybody explain this 'MAGIC" tire that keeps coming up in these discussions? I'm curious what they are, where you get them, and how to validate it is indeed magical.

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22mm Attack (and its inherent aero goodness) w/ 24mm Force or TC or 23mm SS Crr

Roller test

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oki i found out what the magic means .. Tom A usually tested attack and force gave him around 33 watts at 40kph; however couple of attack tires actually tested at 27 watts; means whole 6 watts faster - thus if you have this selected aka magic attack this is the grail as it is good aero and this crr is one of the best

Thanks for that R2!

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Soooo, question.

I have a set of HED Ardennes SL + (25mm wide rim) and am planning on ordering 2 pairs. Is it faster to run 24/24, 24/26, or 26/26?

seems to me the fastest set up wd be

SS 23 + TC 26 - assuming it's an aero frame for TT purposes

Whats the puncture resistance like on the ss though? It seems the TC has better puncture resistance so to me, 2-3 watts may be worth giving up for a little extra comfort.

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i would probably go for it esp for courses with no known high yaw wind.... but i said what wd be probably the fastest

I raced them the first time at IMAZ 2015. Felt great, and still going strong. They now have several nicks in them from riding over some gravel/salt on the winter roads in Boulder, but I haven't had a flat yet. I have not used the Zipps so can't compare with those specifically.

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A couple of years ago I raced on a SS 23mm front for 3 or 4 x 70.3s and 1 x 112mi with a few shorter ones in there. No issues.

Last year someone borrowed my wheels that had 2 x TC 24mm and slashed the rear at Raleigh 70.3

So the short answer is: it depends.

Does anyone have any leads on acquiring 24 Turbo Cottons at the moment? Google and EBay coming up empty.

Did you check your local shop to see when they might be available? I'd call Specialized too. I have no idea when mine will be here

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In that case, I have 2 for sale for $100 each ;)

One brand new, one with 20 miles.

You had to say that didn't you? I'm racing raleigh 70.3 this year.... crap

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wrong forum, move it over fella ;)

My LBS has 24's and 26's in stock. If you're antsy, I'll pick them up and send 'em to you for my cost. I need to drop by this week anyways.

PM me if you are interested.

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Found them locally. Thanks.

How many miles are folks putting on the turbo cottons before tossing them? I raced on them last season, 2 70.3s, a full IM, couple olympics, and a sprint. maybe another 100-150 miles of general use as i had no alternative on particular days.

well the longer you use any tire, the faster it rolls, but the wider it presents to the wind. Ride 'em longer!

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Anyone think that the vittoria corsa speed may be better than the turbo cotton? Same 320 tpi cotton casing, but in a slightly narrower form factor. Unless the graphene compound is slower than specialized, they seem to have enough in common to think that it will have great Crr and better aero from being narrower.

That's in interesting question. Graphene and the new Michelin have yet to be tested independently but if their claims are correct they will be at the top of the charts on par with the best tires, which also makes me think that there is an upper limit

Holy grail I think would be to make an aero turbo cotton or for the Conti engineers to make the GP 4000 S a better rolling tire

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My team is sponsored by vittoria, and I have a few corsa speeds on order. Happy to send one off to a forum member for Crr testing.

Some people seem to be running a 26 mm tc in the rear. Why the wider tire in the rear? Is it faster than 24 mm? More stable for turning?

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Wider rear tire: more cushion for the push'n, lower CRR, (generally) better shielded/in turbulent air mitigates some of the CDA penalties of a wider tire. Think discs also mitigate tire size to a decent degree?

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Crr-wise, I found it only .0001 faster...so, barely.

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Two quick OT questions: do you have any thoughts on the Zipp SLSpeed tubular? I would assume the 24mm version is aerodynamically optimized for the firecrest rim, no?

do you find it curious that a wider tire only rolls that much faster? Is it possible that there's a limit to how fast a tire can roll?

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Bigger tire at the same inflation pressure will have less deflection, therefore less deformation in the casing.

I raced with the SL Speed last season, 24 mm up front on an 808 firecrest, 27 mm in the rear on a Sub 9 disc. They felt fast, but I doubt I could really tell a difference. Two observations, though. First, wet grip was abysmal. They even come with a warning "for use on dry roads only". Went down at 13 mph at Chatt 70.3 on wet roads. Second, I found the handling rather sketchy / unstable. On the same descent one day to the next, I was white-knuckled on the horns with the SL Speed vs. full aero >5 mph faster with a Conti something or other (replaced front only). For those reasons, I'm dumping the SL Speed for this season.

I think it just shows that the Crr on that tire is more dominated by the tread (glued on - appears to be same mold, i.e. same width) rather than losses in the casing.

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I have no insight into whether or not that's a good assumption...sorry.

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.0001 is still over 3%.

right, but other tires have gained like 10% between 23/25 and 24/26 options.

just wondering

I think what Tom says is right.... it's a product of tread AND shape... and so it's possible to max out on one and so not get much change from the other when going wider. I'm going out on a limb and saying that the current crop of .0029 tires on Tom's chart won't be topped by much more than that .0001

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oki last one - i jsut changed set up for 25mm - what is the usual difference in psi between the 23 and 25mm

About 1 bar , don't know the psi

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-shoki

10-15 psi drop is probably typical. If you're riding on good asphalt, I'd keep it in the 110-120 psi range if you want the lowest Crr.

How does the Force perform on a Renn 555 disc? Is it a good fit?

It will bulge out a fair amount. Force is a little wider than a GP4000.

Would I be better off with the GP4K that I'm using now on the Renn disc? Should I use an Attack on the disc; it's what I'm using on my front wheel.

Michael

IME the Attack usually has better Crr than the GP4000, but that isn't always the case. I'd use either before the GP4000.

So your preference is the 23 mm Supersonic, correct? Too bad the tire life is so short.

Race tire, optimized for the purpose.

Well sort of. It might be even better with some boundary layer tripping grooves.

Actually having a short life is a good thing. Tires tend to lose their aero properties pretty quickly. The lack of tread on the SS has you replacing the tire more often and so it might actually be a positive.

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Just got my 24/26 mm tires. What's a good starting pressure for these? (I'm 165 lbs). I'm thinking 105/100. I have always ran gp4000s and run 100/105 psi but I feel like they should be higher.

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What width rims and what tubes? On my uber-wide Hed+ rims (21mm internal width, which adds ~2mm to the mounted width) and using latex tubes, I run 80psi front/rear.

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Zipp FC 808 front and super 9 rear. Vittoria latex tubes.

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I would probably go more like 90/95psi. I also weigh 165#

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Thanks. How do the width's compare from the Zipps to your HED's? The HED's are wider?

With running a wider tire in the back (26 mm), wouldn't a higher pressure in the back negatively impact stability (narrower contact patch)? I know it's minimal and probably not even noticeable, I'm just thinking theoretically in my head.

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The Heds are wider and add ~1mm more to the mounted width than the Zipps.

When I was running 24F/26R on my road bike, I would typically inflate both to the same pressure.

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Hi Tom,

I'm running the same Zipp 808/Super-9/Latex set-up but is lighter coming in at 150 lbs. What tire pressure would you recommend? I'm doing IM SA on Sunday. The road quality is probably not great. Would you run a even lower psi on South African tarmac? :)
Hoping the road quality don't eat my Turbo Cottons alive haha

Cheers

Probably reduce by ~5psi...you be the judge ;-)

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I'm running a Flo 60 front, and Renn 555 disc rear on my TT bike. Would the 24mm SS tires be my best bet front and rear? I currently have an Attack front and 23mm 4000s rear. I just picked up a couple of S-Works 24mm Turbos, though I'm thinking about putting them on my road bike. With my rims, but is my best option?

And at 150 lbs and latex tubes, what would be a good tire pressure? I'm currently running 100 psi front and rear - likely too high.

Does anyone have any suggestions or experience running turbo cottons on a Zipp super9 on a Cervelo P5?
Is it possible to squeeze a 26mm in the rear? I'm currently running 23mm supersonics and looks like there is a bit of room still.
Or would I be best sticking with 24mm front and rear.

Cheers

Phil

I run a 25 conti 4000S on my super 9 disc and P5. Did have to back out the dropout screws for clearance tho.

Thanks. May go with the 24's then just in case!

Should note can't get larger than 23 on front. Rubs the brake and downtube.

Oh. :-( balls!
You don't think you could squeeze a 24 in there?
So you running 23 Conti 4000 on the front then?
Maybe I should just stick with the supersonics then.
Always good to know they fit before you blow $200 ish on a set of tires!!!

Man, 24 would be tight assuming TC's fit like conti - a little wide. I'd be worried about picking up a pebble and wedging in there.

Think I will stick with what I have then. Maybe increase a little on the rear.

Phil

Sorry for the necropost, but what IS the conclusion of this thread??? I'm currently running 23mm GP4000S II for road racing. I have a set of 23mm Corsa Speeds on standby. Should I switch to the Corsas? Or should I go back to racing Turbo Cottons?

Why Turbo Cottons? They have been shown to be slower aerowise and no faster than the SS.

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That's why I'm asking. Assume low yaw (which is generally the case in road racing anyway). Actually, assume one of the three tires mentioned. Which would you pick for road racing???

A. 700x23 GP 4000S II (I currently race and train on this tire - it has been reliable as hell)
B. 700x23 Corsa Speed (Own it, but never installed)
C. 700x24 Turbo Cotton (I've raced on this in the past. It feels fast, but doesn't feel as grippy as 4000S II in the turns. Plus it cost more $ and doesn't last as long as 4000S II)

I would choose neither, I would personally go with the SS. If I didn't run an SS on the back I would go with the new 25mm GPTT>

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I TT on SS front, GP TT rear and road race on the vittoria corsa speeds (tubeless). I was road racing on the vittoria corsa g+ in 25c, but the rr tests of the speeds compelled me to make the switch. TC gives up too much aero for TTs, but makes a fine road race tire.

GP4k is an awesome training tire - still working through those on other bikes, but don't race them any longer.