It wouldn’t be Slowtwitch without complaining.

The front 858 is narrower than the rear. From what I’ve read it’s slightly faster than an 808 NSW but more stable.

I’d buy one. I think it looks cool.

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Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

Pretty much the only -valid- reason to spend over 1500 on a wheelset these days.

I would be more interested in tests showing its effectiveness than opinions.
Not even Zipp have published wind tunnel tests. Not even for the 454, which has been out since November 2016.

Neither did Cervelo for the P5-X.

I'm wondering if companies are choosing not too because everything is so close. Kiley's test proved it. So what's the point of releasing the data? So the 1% of triathletes that are on Slowtwitch can argue about it all day?

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Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

In that case we got a test to provide proof/insight on some claims, which was great. With the *5* wheels we have nothing but claims.

The test I would be interested in seeing is a stress/durability test of the rim/nipple interface.

I may well be wrong but to me it seems like the rim design will amplify/localize the stress at the spoke nipple rim interface. Basically the tension of the spoke is placed at the top of a point. Zipp's massive hub recall would indicate they don't have a great history of catching this type of issue and catastrophic wheel failure can cost a lot more than the most expensive wheels on the market.

Well if I am not mistaken, while they also claim "the fastest wheelset yet", the main selling point of these is the stability in the wind, so we can be in the aero position longer (which is in itself again fast and aero). How would you measure/quantify that? Are there even any windtunnels that can simulate wind gusts? I can measure and quantify in the windtunnel that wheelset X at wind angle Y needs Z watts less than the competition, that's easy. But how do you measure "I feel more confident with my new wheelset"? Its something swiss side tried to measure with their instrumented bike thing, but even if you get a measurement that "at winds above 50 km/h he needs to leave aero position", that would be too individual for every person on the planet for Zipp to make quantifiable claims about it. Probably something like "9 out of 10 People report that they feel more comfortable with the 858NSW compared to a 808FC" would be the only relevant data you could get in this respect, which would kind of be the point of the post, to get a feeling what people think about the wheels =)

I'm willing to answer the bit in bold....... No - You cannot feel it's more aero (assuming that means it produces less aerodynamic drag)

As for it being more stable in wind, that's less certain and hands on experience might actually yield some information.

All day? Don't you realize that arguing is an endurance sport? Train more!

I have a set of 454/858 combo that came on my Speedmax SLX 9 SL. I've only ridden them once on a VERY gusty day today here in San Francisco. I can't compare them to 404/808 NSWs, but compared to my Bora 50s they definitely have a different feel with respect to how the shed gusty wind. Whereas on the Boras the gusts kind of build and break off in large pushes, the 454 front sheds wind in lots of little pushes. Perhaps it just a new sensation for me, but I actually found it more erratic and unpredictable; but on the positive side, the steering corrections required were small and I felt less likely to crash off the road. Bottom line, the jury is still out, and I might try to sell the wheels while they're still new.