I am in the same boat - I am doing as much research as possible on the subject and everything IMO is pointing back to Specialized Turbo Cottons (26mm) on a set of Enve 7.8 rims with latex tubes. I have pretty much the same parameters as you - honestly the only thing stopping me from going that route is the sidewall color of the Turbo Cottons (maybe riding a Speed Concept also)!

Interested in this as I've also just bought some 7.8's.

Enve say tubeless is quite a bit quicker. It also allows lower pressures giving better CRR over any less than perfect surfaces (this was from a different source, but I can't remember where, sorry. In short: two modes of rolling resistance one decreases with increased pressure on a smooth surface, the other increase with tyre pressure steeply on rough surfaces).

Edit to add: source was Silca https://silca.cc/...stance-and-impedance implied to me that being a little low on tyre pressure wasnt terrible but being too high was not a good thing.

There was an Ero post from ~Aug 2017 that said a tyre inflating to a measured 28mm on the Enve's was very quick.

I've gone for 25 Schwalbe Pro One Evos that I'll run tubeless. I have some on a road bike that are great, and some bad experiences with Vittorias in the past.

Question for any that have done it: if you fly with tubeless wheels, do you fully deflate the tyres and risk the bead popping / covering everything in latex? Deflate to around 20 PSI?

Why do you say that? The Turbo Cotton lost pretty clearly to the Supersonic in the TomA testing and the Corsa Speed in the Gerlach testing.

And it beats neither in rolling resistance.

I rode all year with turbo cotton 24c in front (clearance issues with 26) and a 26 rear, latex tubes and Enve 7.8 (rim brake).. When if I end up with 7.8 disc wheel set or stick with my 5.6 disc.. I will still use Turbo Cottons with Latex.

CorsaSpeeds.. I don't find them confidence inspiring in any amount of dampness and I think they flat more easily as well. No thanks.

as for that Roval wheel.. yeah I want that too... or the Enve disc but I like the fact that the Roval is ~200g lighter.

You're certainly not completely wrong. The Turbo Cotton clearly makes the final selection of the fastest 4-5 road tires. And the puncture resistance is compelling and has been both anecdotally and scientifically validated. It just has the drawback of being one of the least aero of those final 4-5. But that could be outweighed by puncture resistance and well-regarded grip of the "Gripton" compound.

Hey There Allanhov,

I am the engineer of the 321 disc. Thanks for considering it as your next wheel. It is unclear if you are talking an everyday setup or for racing, but let me provide some more insight.

Our UCI athletes are running the turbo cottons for good reason; they roll very fast, have a great feel, and have good puncture resistance. The pro's will run latex, which I would only recommend on known courses, and even then would be a tough pill to swallow for triathlon...It was a big challenge to convince the UCI teams to ditch tubulars, even with all the data in the world pointing toward the benefits. This may seam trvial, but I think that is a strong indicator of the performance.

Tubeless is the next step in performance. Of course, there are some inherent differences with tubeless, but know that we did plenty of development to make it a seamless experience. Which tire you decide to run tubeless will ultimately dictate your experience, and while we tested a variety of tires, we can only consistently stand behind our Specialized tires. For that reason I recommend ours, but we did see good performance with Schwalbe's in tubeless configuration.

A lot of the tubeless headaches disappear with the 321 disc wheel because there are no nipple access holes in the tire bed(fully solid). We also adjusted the bead seat diameter to account for the removal of a rimstrip. This further reduces the assembled wheel weight compared to our competitors. Not only is it by far the lightest disc wheel clincher, but there is potentially an additional 30g+ saved there.

You have narrowed down on some good tires, and your questions are right. I think you cant go wrong since you chose the 321 to start with ;)

Interesting tidbit about a cancelled hour record attempt by Tony Martin! Interesting that he hasn't tried yet - I guess his later teams might not have been that interested in supporting him in that.

So you're saying the narrower wheel, even with a tyre that is bulging out a bit, might be faster in some frames than a wider disc with a better matched width to the tyre?

It was probably a rhetorical question, but for outer rim width I like to know both max width and width at the outer brake track. The first one can be kind hard to do on discs, of course, but the latter one should be pretty straight forward (I guess the 27 mm stated for the Roval 321 is on the lower/inner part of the brake track?).

One thing you could have done was to instead decrease the inner rim width to narrow the tyre, but I guess you wanted the wide internal width for comfort reasons (have yet to see any real impact on Crr from that).

Do you see any performance benefit from tubeless tyres? I have yet to see anyone measure any benefit vs. clinchers with latex tubes - I ended up using latex tubes for Worlds, would have run the Corsa Speed 25 mm tubeless if that had been a better fit for the rim (mechanic was not amused having to remove the Corsa Speed having spent all morning getting it to seal...).

And yes, UCI seems to have gotten very fond of hilly/mountainous TT's for some reason...

I was surprised that MTM found a 25mm Corsa Speed being too wide for the rim.

What width did you found the Schwalbe (Pro one I pressume?), to be good?

It will go on my QR PRSix Disc frame, and hopefulle I will have room enough.

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Gator,

Thank you for this information - it truly helps hearing from a representative from Specialized. This post does lead me to ask if Specialized is currently developing a Turbo Cotton Tubeless tire?

My buddy with 7.8s + Roval disc runs Schwalbe One Tubeless, 25mm. Have no idea on actual CRR and aero data, but seems a good fast tire with decent puncture protection.

Have you seen how the Schwalbe One 25mm fits the 321? Does it fit the rim nicely?

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Schwalbe One Tubeless 25mm looks like good tire with decent puncture protection, but does not get a good crr in Tom A's test. Ref: https://docs.google.com/.../edit#gid=2047093726

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TBH I haven't looked at it closely.

Not sure if Tom tested the latest version. The first One Tubeless was pretty poor, but they updated it in 2016. I see its now called the "Pro One Tubeless"

According to BRR the latest model in the top ten CRR of tires tested, on par with a GP Force II... https://www.bicyclerollingresistance.com/...ro-one-tubeless-2016

You are correct. The Pro One Tubeless looks pretty good :)

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Thanks everyone for sharing here, great info. It would seem the GP TT also slots in here nicely with very low RR, albeit no ability to run tubeless. 23mm front and rear would get near the ideal measured 26mm for the Roval 321 and likely profile nicely with the front 7.8.

The new Pro One seems to be getting quite a few negative comments/reviews across BRR and Amazon regarding lack of puncture durability, numerous cuts and general poor durability.

They've been pretty good for me over the 3500 miles I have put on them over the last year. I run them on Easton wheels setup with orange seal; however, the sealant had dried up before this guy found my tire:





Happened about 45-50 minutes into a 3:15h ride and outside of the quick loss of air, that I dismissed as something getting caught up in the seat tube cut out, the incident was uneventful. I pulled it once I got home, added some more sealant, and the tire is now as good as before. I know many others have had issues, but that hasn't been the case for me.

My setup:
Easton EC90 Aero 55 (19mm internal)
Schwalbe Pro One TL 23 front (25mm actual)
Schwalbe Pro One TL 25 rear (28mm actual)
PSI 55 front and rear

I am anywhere from 59-61.5kgs depending on how my week is going and I ride all surfaces with the wheels/tires. Now, the caveat is that 95% of my roads are perfect and smooth as glass with more miles getting paved all the time. I also don't live anywhere where goat heads or other crappy material may be found in the road ways. Finally, I ride mostly country roads and not roads with shoulders that contain road debris/glass/foreign objects. That being said, it was exactly this last bit that caught me out 2 weeks ago (shoulder, entering road construction area, and lots of crap on it).

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Always nice to get both sides, glad to hear the Pro One's are running well for you. If you don't mind me asking, what region do you ride in?

In my first race on the Corsa Speed's I ended up with a flat - small shard of desert rock/glass down in the Las Vegas area. I'm thinking something with a slightly thicker tread would have likely prevented this, but you never really know.... I'd imagine these conditions are particularly hard on these low RR tires.

Virginia Wine Country

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