Not a disc expert, but it seams that there is a consensus that modern 25mm tubeless are faster than 23mm (not much more drag, and less rolling resistance)

Wheels need to be optimized for 25mm (25 / 1.05 or wider)

Yeah, you're gonna improve a crap-ton on rolling resistance and like a bit on aero with that.

Worth it. That's about a best-of-class setup you describe. You quibble with slightly faster tire/wheel configuration, but what you desribe checks the "fast AF wheels" box.

Disagree with the other poster. Rolling resistance is a "wash" between 23mm and 25mm (assuming normalized pressures, etc), and 23mm likely to be slightly more aero.

Good to hear. I'm already pretty fast and happy with current setup, but I haven't tried any other setups, so I wouldn't know.
I did some experiment with tire pressure lately. in 10 mile loop, I was 2-3 min faster with 80 psi compared to 95 psi. Condition of the road is not that smooth overall. It less bumpy and I was faster, so you can kinda adjust rolling resistance with tire pressure I guess. One more question. Super 9 disc is Shimano 10-11 speed compatible, right? I have 10 speed.

Actually, the 858 NSW is only 24.4mm wide.... so optimized for 23mm. My bad, I thought that everyone was optimizing for 25mm now a days

It’s a great set up (I have the exact same disc set up but the 808 NSW with GP5000/latex front), really can’t justify the 858.

I’d guess the biggest impact of your upgrade in feel if nothing else will be going from butyl in the Competition to Latex.

Enjoy!

Yes. You can use a 10sp cassette on any 11 speed wheel. Just need to use the right spacer. Pretty sure it's the 1.8mm spacer that comes with the wheel AND the 1mm spacer that comes with the cassette.

We’ve specifically looked at this (during some of our internal development) and on an 858 we found that a 25mm tyre was more aero than the equivalent in 23mm.

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AeroCoach UK
http://www.aero-coach.co.uk

My 858NSW set came delivered with a 23/25 setup and I immediately moved it to the 25/25 setup. Feels great and works great with the 25mm setup. I thought I also read that Zipp recommends a 25mm tire

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Cheers, Ray

So it looks like answer is 25mm GP5000 with latex tube then. Ok, thanks for the input guys.

I have a thing for that Sawtooth design on 858 NSW.

What tire/width/tube do you use for the disc in the back?

So, i'm not and expert... and i'm not saying that 25mm will not fit on the 858 NSW.

What i have seen (mostly the Silca Podcast with Josh Poertner, who used to work for Zipp) talk about the 105% rule... which is that the that for optimal aero results, your wheel need to be 105% of the with of the tire. Thus according to that rule, the 858 will work best with 23mm (considering aero only). But i didn't do any aero test on it... and since price pay is the most important factor of perceived performance (according to the same podcast), they must be awesome.

Pretty sure that if you use sub optimal tires for those wheels, you could get similar aero performance for half the price... :)

Taking money out of the equation there is likely to be some marginal gains....but what distances are you talking about race wise? That seems like a huge amount of money to be dropping for what probably amounts to a few seconds benefit??

I recently made that exact same move from Zipp disc/808 tubies to Super 9/858 disc brake clincher. Conti 5000 23 front, and 25 rear. It is hard to see how to beat the set-up. Enjoy!

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David
* Ironman for Life! (Blog) * IM Everyday Hero Video * Daggett Shuler Law *
Disclaimer: I have personal and professional relationships with many athletes, vendors, and organizations in the triathlon world.

Sub optimal? Possibly. And costing me what? Maybe 60sec over 112mi, if that? Fair enough. How do you explain the 25mm rear tire on the 858NSW with a 23.7mm width? For comfort since there is more shielding and less affecting aero?

And similar aero for half the price? Are you talking in a straight line with no crosswinds? I can say the 858 feels so much more stable than my 808 in crosswinds so the confidence in aero with crosswinds is much better when using the 858.

FYI....I will definitely do more personal testing on the 23v25 front to really dial in what I am going to want for a race. I'm not drinking the kool-aid for a specific tire size and will actually test and capture metrics as well as the trade off for comfort before making a final choice.

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Cheers, Ray

Please keep us updated on your testing.

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David
* Ironman for Life! (Blog) * IM Everyday Hero Video * Daggett Shuler Law *
Disclaimer: I have personal and professional relationships with many athletes, vendors, and organizations in the triathlon world.

I believe the marketing.... the more you pay for your wheels, the faster they are, they are more stable, the better they look ... and they could even talk to you when you go into a dark places.

But aerodynamic came a long way over the last few years and the difference between all of them is not that big... using SwissSide Data, going from 625 to 800 save you 2 watts (at 350w)
https://www.swissside.com/...riant=13017166053475

Changing the tire / wheel pairing change way the wheel behave... which could also cost you few watts. (something to do with the air detaching, please refer to the Marginal Gain podcast for details)

Now the question is how many watts.... more or less that having a shallower wheel with optimized tires ?!?
(actually really hard to get good info on that)


Don't get me wrong, tires width is a very important choice... you just need make that choice before you grab the most expensive thing on the shells, because it look cool.

I'll definitely pay extra for a wheel that can talk to me when I go to dark places :-)

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Cheers, Ray

Normally its safe to agree, but as Xavier of Aerocoach already chimed in that in their testing a 25mm was faster, I'm inclined to believe that data over a general rule here. Also Zipp says run a 25mm so thats two points for there.

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
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Thanks for chiming in Ben. I thought I read somewhere that Zipp suggested 25 as well but I just couldn't point to that reference.

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Cheers, Ray

You went 2 to 3 minutes faster over ten miles just by riding with 15psi less?? Is that right? If so hang on while I go let some air out my tyres🤣.

Messaged my buddy at Zipp, he said 25mm if tubeless, 23mm if clincher/tubes

Thanks for checking on that! For what wheel specifically? Is this for the Super 9 Disc? Not the 858 correct?

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Cheers, Ray

Thanks for checking on this. I will probably go with 23mm in the front and 25mm in the back with latex tubes in both.