Oh, I thought those were highly regarded (at least the current DT Swiss ARC 1400). 
I mean, yes, they are a bit narrow compared to newer wheels.
What? They are rated as some of the fastest wheels on the market, with fantastic hubs. Or are Canyon using some older version?
They are! Sure, they’re not ENVE with the super wide inner width etc, but they’re also 1/3 or the price.
Are the ENVEs 3 times faster for 3 times the price…?
No.
Also, DT and Shimano and a few more still run hooked, which is nice, even if running tubeless 
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Let me rephrase that, they’re great wheels, they’re crap in a crosswind. Love them on a calm day but I find them very unstable in crosswinds, something I never really noticed on other modern 50-60mm wheels
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Mines a 2019 model so very possible they’re an older version
I have the 303s and have to say overall I would be quite happy, they ride nice on the Road and also on Gravel (used with 40c Conti Terra Speeds , 30 Pirelli P Zero and 28c Conti 5000 TR) . But the Freehub Bearing disintegrated after around 1 Year of use, yeah the Going was sometimes Rough and some Rain and Mud riding. But that dissapointed me a lot, bearings overall seem to be ok until now.
Still for the price I got them which was around 780$ they are still an interesting option. Will probably get a Road Wheelset next year that will not be a 303s and keep them as Gravel and Backup set.
DT Swiss brought out a new wheelset with wider rims (ERC 1100/1400). So I think they are also going a bit in this direction. And they claim a better stability in side winds too (but who doesn’t).
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I rode back from the Wed night group ride with a few people, and one of them has had Zipp 303 wheels for a long time (5+ years?). He just bought a Canyon Aeroroad and was telling me how crappy the 303 handle in crosswinds, compared to the DT Swiss 1400 (?) wheels on his new Canyon. Most days we are riding in crosswinds, and he really couldn’t believe how poorly his 303 handled in crosswinds compared to a more modern aero wheel.
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Yeah, about 5 years ago a lot (most?) deep rim wheels were V shaped which is pretty terrible in cross winds. They’re all now much more U-shaped which handles much better.
It should probably be noted that handling in crosswinds is also affected by the frame / fork design…so one person may not have any issues with one particular set of wheels while another may find them to be challenging…with the major difference being how the frame / fork impacts the overall system.
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For sure, but aeroad with dt wheels compared to aeroad with 303s has been night and day for me. Any gust of wind was felt big time with the DTs, almost unnoticeable with the 303s. That’s my take on it, others may feel different
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My buddies Zipp 303 are from 2015. Out here its crosswinds most of the year, hence my forum name.
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According to Zipp’s tire pressure calculator(here) you would need to be over 120kg total system(rider, bike, and accessories) before you would exceed the 72.5psi limit of hookless.
I run 28mm GP5K’s on my 404’s(same inner width as the 303s) at 66 psi rear and 62 psi front. I weigh ~80kg and have zero issues.
ENVE’s chart shows similar pressure recommendations(here)
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Strange, my dicut 1400s on my aeroad take crosswinds like a champ? Better than any wheel ive ever ridden.
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Silca’s chart, which isn’t part of a program to sell you wheels, but is close to what world tour teams are running suggests vastly different recommended pressures.
80kg rider + 7kg bike + 3kg (2 bottles, 1kg tools/spares/phone/gels)
700c
High performance tyre
Cat 1-3 racing speeds
Good pavement (or a crit track)
25c:
98 front, 100 rear
28c:
82 front, 84.5 rear
30c:
73.5 front, 75.5 rear
Secondly, your 404’s external width is 27.2ish mm measured. That means if you run a 28mm gp5k, blowing out to 29mm, you’re losing a ton of your aero gains from deep wheels by not having a 105% wheel/tyre profile. The max tyre you can run on a 404 for it to be worth it is 25c.
I actually had a play around with it again. With a 25c front gp5000, assuming stretching to 26mm, you can’t get below the max pressure as a recommendation until you & your bike weigh 40kg collectively (i.e. you are a child).
So what?
If you want to buy a set of hookless zipps, buy 303 firecrests or 353 nsw’s so you can run a 28c and stay inside safe pressures.
OR
You can run 404’s but you either have to accept you’re just adding weight for no aero gain (you’ve just lost it all due to 105%) and run a 28c, or you can run a 25c and get the aero gain but you need to run it at a pressure that’s going to cost you a lot of RR.
The Silca calculator is a few years old now and as far as I know hasn’t been updated. Interesting that internal rim width (or hooked vs hookless) isn’t included in it and I wonder if it takes into account how much rim widths have increased in the last few years. My assumption is that increasing rim width increases the volume of the tyre, and that both changing width and moving to hookless change the shape of the tyre and therefore the shape of the contact patch and hoe the tyre deforms under load which in turn would impact optimal pressure.
Not doubting Josh Poertner’s expertise, I know he works with some of the top teams and have absolutely no doubt that he is fully up to speed on all the latest wheel and tyre developments. Just wondering whether the current version of the calculator fully reflects all that expertise or if it’s due an update.
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It’s a bit of a reach to say you’ve lost all the aero gain 
. Seems you’re missing the forrest for the trees here. Would a 25mm tire be more aero? absolutely, no argument from me. Does that mean it has no aero benefit when you put a 28mm tire on? Hardly.
Flo tested this. Compare their results on the 77’s with 28mm tires(breaks the 105 rule) to the 49’s with 25mm tires(adheres to the 105 rule). Here
Sure Zipp and ENVE sell wheels, but what does that have to do with recommending tire pressures? What do they have to gain by telling the masses to run an inappropriate tire pressure? I’d bet hard cold cash that if I ran Silca’s recommended pressures I’d be slower. I’d get rattled off the saddle at almost 85 psi.
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If you listen to the most recent Marginal Gains pod, it certainly sounds like it is regularly updated based on testing, etc.
Ah, that’s useful thanks. Though that implies that Josh believes that internal rim width and hookless have no impact on optimal tyre pressure (since his calculator doesn’t ask for those inputs) which is a real surprise to me. Both the Zipp and Enve calculators include rim width, and increasing rim width lowers optimal pressure for any given tyre size. Zipp calculator also captures rim type (hooked or hookless), all else being equal switching to hookless seems to drop optimal pressure by about 5psi. Enve calculator doesn’t specifically capture rim type but does have separate columns for different Enve wheels so I assume rim type is factored in that way.
Interestingly pressure advice from Silca and Zipp calculators is very similar if I plug in hooked, 19mm rims. It’s wider and hookless rims where Zipp recommended pressure is much lower than Silca.
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The Silca chart must not be for hookless rims. ETRTO max tire pressure on hookless is around 73psi not up to 100 that is mentioned. I think also the 2022 ETRTO recommendation was tire width be 3mm or more than internal rim width (so 26mm+ tire on 23mm internal rim width with 303s / 404 @Cory.Rood is using) for hookless rims but they have updated their recommendation to 5mm+ (28mm+ on 23mm internal rim width) for 2023.