At 100 psi the 4000S (12.9 watts) and Attack (12.7 watts) are virtually identical in terms of rolling resistance. The Force (11.6 watts) is a little over a watt faster than the 4000S.

I personally use an Attack on the front and 4000S in the back. On my bike (Blue Triad SL) there isn't much rear clearance for the tire, and I found that the Force is too wide to fit - found out the hard way via a flat in a race!

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Which wheels? The latest conventional wisdom is that wheels and tires work together as an aerodynamic system. For example, FLO's design target is the GP4K2. HED's fastest is the Attack on their Plus wheels.

But hasn't the Attack changed since the HED "Plus" wheels were designed?

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The attack tires seem to have lower flat protection than the GP4000s II, but not significantly faster, and if using less than 95 psi, than tested slower: https://www.bicyclerollingresistance.com/...and-prix-attack-2016

That said, looking at the difference in rolling resistance on the Grand Prix TT, I may experiment with it as my race tire this coming season.

It's roughly 5 watts faster than the GP4000s II, with less flat protection, but with the Vectran layer, seems to offer more flat protection than some other super fast tires it's comparable with.

Worth the gamble, but will mostly use them just for racing sticking with the GP4000s II as my weekly time trial and general training tire due the the lower life expectancy of the TT with the mush lower tread thickness.

Running a Hed Jet 9 plus front and Jet Disc rear which tests fast with contis.

I specifically asked the HED guy in email in December if the current Attack is their fastest. He said yes. His words.

I realize they have tested Attack wheels in the past as the most aerodynamic, but looking at the Rolling resistance difference between the attack and the TT, is an attack front going to be 2 watts faster than a TT front aerodynamically to recover the slower rolling resistance?

I was also under the impression that it was the 22c attack tire that was optimal, but now it's being sold as 23c, I doubt it would test exactly the same. Them saying that they can safely now recommend a 23 mm front seems to confirm they are still using the 22c data for the recommendation.

We traded a lot of emails. I think he said that HED tested on the new version, but I cannot specifically remember. I had GP4K2 tires before, and I loved them. He convinced me on the Attack/Force combo. Part of the story was not just their testing, but he commented on a number of their in-house fast racers and their wheel and tire preferences.

I had personally ruled out the TT tires and the Speed Corsa tires because of comments here and other areas about flat vulnerability. I prefer to train and race on the same equipment, so low treadlife and flat propensity is a bad thing for me. That, coupled with HED's love of the Attack tires, made my personal decision to move from GP4K2 to Attack/Force easy.

If you are thinking about your personal tire choice for your HED wheels, I encourage you to reach out directly to HED. It was a fun exchange. They might be able to answer your particular questions so that you do not have to guess or read between the lines from a reply that does not contain the full context.

I do temember just days ago having a video sent my way where HED was specifically talking about the attack and even brought up the 22c tire size, so they will have needed to test both once the new ones came out.

I don’t mind swapping for races, been running butyl/gp4000sii for years, and looking at 8-10 watts with a TT/latex combo, which could be a difference maker, but want to test out for myself propensity for flats a bit in training before risking a race.

That said, guys like Kienle seem to do ok on them!

Thanks for the response, I may reach out to HED tonight.

The guy I was trading messages with was the guy who made that original video. I referenced it when I was asking him, because it had been out several years. This is what I wrote:

My only hangup was the language of the response “Attack is still the most aero tire for a plus wheel”

I do believe that it may well be the most aero, but is it 2.5 watts per tire more aero? :p

Based on the language I’d assume they just mean most aero and I think the main differences going to the TT is tread thickness, which can alter aerodynamice a bit, I would be surprised if it was that much :p

Sounds like an email will be sent out for sure :p

Would you mind shooting me a PM with the email address of whiever you have been chatting with if it isn’t a standard contact page address?

[quote dfquigley

I do believe that it may well be the most aero, but is it 2.5 watts per tire more aero? :p[/quote]
It just might be. I just posted in another thread about the HED JET+ Black so it is on my mind, but remember from the wind tunnel test I did last year, thanks to the support of many of you, the old 23mm supersonic performed considerably better than the new 23mm supersonic. For those that are NOT familiar, the old 23mm measures quite a bit more narrow than the new one.

Those results are here => http://www.thomasgerlach.com/...ria-corsa-speed.html

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PM Sent. Let us know what you learn.

So it sounds like corsa speed outperforms the TT both aerodynamically and in rolling resistance, too bad there isn’t the comparison with the attack!

I was actually reading the thread leading up to that wind tunnel testing last night, but there was no update in that thread, so didn’t know whether it happened!

Any reason not to use the corsa speed other than trying to change a flat with the tight tires, or any reason not to try it out tubeless?

If HED does have numbers comparing the attack and TT, given this comparison, we could still extrapolate to the corsa speed.

Thanks!

As Tom A has said many times, ~"RR can make up for many aero sins." On the back it is almost certainly the right choice. You could make various arguments on the front given different wheels, conditions etc, but at the end of the day we need to be out there riding. Top Conti tires are not a bad a choice. And I have had good success running Corsa Speed tubeless but running tubeless is definitely more of a hassle.

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Fantastic.

So it sounds like corsa speed or attack are the front runners given the corsa speed vastly outperforming the conti TT aerodynamically but much happier with the corsa speed rolling resistance numbers too vs the attack.

Have you had success with not getting a ton of flats on the corsa speed?

Going from gp4000sii with butyl tubes to a corsa speed, will probably take a good handful of seconds off a local 10 mile tt let alone half and full iron times, assuming i don’t flat.

Just ordered a pair of CS from my LBS ( on backorder til feb in Canada ).

Thanks for the feedback Thomas Gerlach.

Still following up with HED, but sold enough to try them out.

One thing to add to TG's test data. Note that he tested the GP TT 25c tire width not the 23c. Since it is likely that the new 23c SS utilizes a variation on the GP TT casing it isn't unreasonable to speculate that the 23c GP TT would have performed similarly to the new 23c SS in TG's wind tunnel testing. In TomA's Crr testing the 23c GP TT is the Conti tire that performs closest to the CS TLR in terms of rolling resistance.

I missed that with the quick read, and incorrectly assumed same tire widths to control variables :p

My CS are on order, but will be march ir so before I can test them out!

Thanks again!

I have never flatted on a Speed, then again, I rarely if ever flatted on Supersonics as well. YMMV

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Been 3 seasons since I have flatted, and that was getting firced into some really gross stuff on the side if the highway training.

Seems it is wirth the risk!

You can see why the Corsa Speed tires are potentially more delicate than other tires. The construction is totally different than most. Most tires are molded as one continuous blob of mixed materials with more protection on the sidewalls and typically a thicker tread area. The SC has a light cotton casing that is directly exposed. And then, the thread cap is very thin and glued to the casing. I bet it rides like clouds in the wind.

I was looking at some turbo cottons the other day, crazy difference!!