Typically, I’m not a huge fan of 50 mm deep wheels. For the riding I do, the extra bit of depth comes with an unwanted weight penalty that usually has me reaching for shallower-profile and lighter-weight wheels. But the Cadex 50 Ultras are unlike most other 50 mm wheels I’ve ridden. For starters, at just 1,365 grams (including tubeless tape and valves), the 50 Ultras are lighter than all but the Roval Alpinist CLX II in my test quiver, And those climbing wheels are 18mm shallower and far less aerodynamic. When comparing the 50 Ultras to other 40 to 50mm wheels, their weight becomes even more remarkable.
To put it in the simplest terms possible, Cadex made a 50 mm aero wheelset that’s comparable weight to many climbing-focused wheels. To achieve this blend of low weight and aerodynamics, Cadex created a new hookless 50 mm rim featuring much of the same technology as the Cadex 36 wheelset launched last year. The new 50 mm rim has a 22.4 mm internal width and a modern 30 mm external width.
The wider 22.4mm tire bed creates a rounder tire shape, compared to narrower rims of the past, which in turn helps to improve grip and handling. Equally important for racers is the way the wider rim integrates with higher volume tires to boost the wheel’s aerodynamic properties, at least according to Cadex’s internal testing.
The most eye-catching feature of these new wheels is Cadex’s new Super Aero carbon fiber spokes. Compared to Cadex’s previous carbon spokes, this new spoke, as the name implies, features a much wider bladed profile for added aero-ness and super-ness. Despite the much deeper cross-section, Cadex claims that the new spoke still offers improved crosswind stability.
As with previous versions of their carbon spokes, Cadex uses the same aluminum ends for the Super Aero spokes, which makes them serviceable and replaceable. Home mechanics will need a DT Swiss inverted hex tool, and a proprietary Cadex spoke holder to perform a spoke replacement. Cadex notes that while these supplies are available to consumers, most folks should take the wheels to an authorized bike shop for easier service.
At the center of the new wheel is a new hub, dubbed R3-C40 Aero, that spins on hybrid ceramic bearings. The hub's name actually gives some useful information; the R3 indicates that these hubs use the R3 freehub body standard instead of previous Cadex wheels, which use R1 and R2 freehubs. C40 refers to the 40-tooth (down from 60) ratchet used for engagement. Unfortunately, nothing about these hubs is compatible with the previous generation of Cadex wheels. Meaning that if you own Cadex 36, 42, or 65 models, none of the hub parts are interchangeable.
Though Cadex currently uses three incompatible freehub designs on their wheelsets, the brand confirmed that moving forward, all new wheels will use its R3 freehub design. This isn’t too helpful in the short term, but it shows Cadex’s commitment to future standardization across its wheel lineup.
Price, Competition, and Aero Performance
Getting your hands on a set of these will cost you $3,500. Which, yeah, it’s an expensive wheelset. For less money, riders could pick up any number of great wheels from Enve, Roval, DT Swiss, Reserve, or Bontrager—all of which will be quite good and cost less than $3,000. But even the lightest 50mm (or thereabouts) wheels from these manufacturers will be heavier by 100 to 200 grams.
A harder question to answer is how all of these options stack up in terms of their aerodynamic efficiency. Cadex provided data from four tests it conducted. Cadex tested its new wheelset against Enve’s SES 5.6, a previous generation of Zipp’s 454 NSW, DT Swiss 50 Arc 1100, and Roval Rapide CLX. Because I don’t have a way to independently verify these tests, I tend to approach manufacturer-provided data with a lot of skepticism.
In three of the four tests conducted, major factors were too different to be useful as a direct comparison. In one test, all the wheels used different tires. In a second, the wheels were tested on the same bike, but again with a variety of tire models mounted. In a third test, different bikes and tire combinations were used. Not surprisingly, the Cadex 50 Ultra did come out on top in all three of these, but the use of various tires does not confirm if the 50 Ultras are actually faster or if the other wheel, bike, and tire combinations are simply less optimal.
Cadex showed one test in which each wheelset was fitted with a new 25 mm wide Cadex Aero tire. In this test, the Cadex 50 Ultra came out as the fastest combination again, but it was incredibly close. The test data showed less than a one-watt advantage for the 50 Ultras versus offerings from Enve, Roval, and DT Swiss.
This confirms that, yes, the Cadex 50 Ultras are fast when used with a Cadex Aero tire. But to truly know the fastest setup, you’d have to test all the wheels paired to all the tires because the wheel and tire interface can result in significant gains or losses. For the purposes of most riders, I can say that the Cadex wheels feel quick in a straight line. This was confirmed in my ride testing, but I cannot conclusively say they are the fastest.
The warranty information on Cadex’s website is fairly vague, so I reached out to Ewan Campbell, Head of Global Product Marketing for Cadex for an explanation of the details. “ Globally, the 2-year Cadex warranty covers just about everything except consumable parts such as bearings or spokes. In the USA, any Cadex composite product damaged while in use would be repaired or replaced by Cadex USA free of charge, no matter the circumstances. This also covers damage done while racing. ”
I consider Reserve Wheels’ lifetime warranty policy to be the gold standard, with Zipp’s ranking a very close second. The Cadex policy looks good as well, and as always, it’s nice to see more companies standing robustly behind their carbon wheels with robust and easy-to-understand replacement policies.
The performance of these wheels can best be described as addictive. They are noticeably lighter than comparably deep disc brake wheels, and they get quite close to some of the dedicated climbing wheels as well. But as with other Cadex wheels, their superpower is stiffness.
The Cadex 50 Ultras accelerate like no other wheels out there. At slower speeds over flat and rolling terrain, these wheels pick up speed and change direction about as close to instantaneously as you can get. Due to the wheels' high stiffness and incredibly low weight, this ability to accelerate is only magnified on hillier terrain.
These wheels simply feel incredible. I tried them on several different bikes, and while many high-end wheels have the ability to transform the way a bike rides, the 50 Ultras took this to a whole new level.
Typically, a high level of stiffness and a deep rim profile results in pretty harsh riding carbon wheels, and while the 50 Ultras are certainly stiff, they rode better than I expected. For my road testing, I used 28mm wide Cadex Race tires set up tubeless. With the wheels’ 22.4mm internal rim diameter, these tires inflated closer to 30 mm. Typically, I run between 60 and 70 psi on a setup like this, which results in a pleasantly smooth ride.
For how good these wheels are, they are still not perfect. There were two areas of concern for me, the main one being the wheels' crosswind performance. These wheels were noticeably twitchy when riding in windy conditions. This was most notable when getting hit by a crosswind gust. I would sometimes find myself getting startled by how much these wheels wanted to move with the wind, particularly on fast descents. Despite Cadex making claims to the opposite, I have a strong feeling it has something to do with the much deeper Super Aero spokes. I don’t have verifiable data for this, but after riding the 50 Ultras back to back with other aero wheelsets that use traditional steel spokes, some of which were actually deeper than 50mm, the difference in crosswind stability was noticeable.
The second issue is much more subjective: freehub noise. I’ve ridden plenty of very loud wheels, but these new Cadex hubs were just extra loud. I realize some riders might consider this to be a bonus, but I just couldn’t stand the noise these wheels made. They weren’t just loud but also high-pitched in a way that made me avoid coasting, especially if I was trying to have a conversation with the rider next to me. To be fair, freehub noise is certainly a matter of personal preference, and twitchy cross-wind performance is a common issue for many wheels at this depth.
Ultimately, the 50 Ultras' flaws feel minor due to the wheels’ incredible riding characteristics. There’s nothing quite like these wheels on the market. Sure, you can find a few wheelsets that are lighter, but they won’t be as aero. You can also get wheels that are more aero, but they won’t be as light. If you’re looking for a 50mm deep wheelset that’s light enough to be considered a climbing wheel, the Cadex 50 Ultras should be at the top of your list.
Test Editor Dan Chabanov got his start in cycling as a New York City bike messenger but quickly found his way into road and cyclocross racing, competing in professional cyclocross races from 2009 to 2019 and winning a Master’s National Championship title in 2018. Prior to joining Bicycling in 2021, Dan worked as part of the race organization for the Red Hook Crit, as a coach with EnduranceWERX, as well as a freelance writer and photographer.