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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Support cancer research with the world's longest annual charity bike ride.
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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.