After helping to lead the charge towards aero wheels in the mid-90’s, the French wheel giant all but fell off the bandwagon, leaving its hallmark aluminum/carbon hybrid rims virtually unchanged for a decade and adding only climbing-oriented, lower-profile wheels to the range. Four years ago, though, internal research and development into wheel aerodynamics ramped back up.
The result is the new CXR80: Mavic’s purple suit, its splashy re-entry into the top of the aero wheel game. It may have stepped away from the top end of the aero world for nearly a decade, but Mavic has returned with a vengeance, claiming that its new 80mm aero tubulars beat the best available — faster than Zipp’s 808 Firecrest and faster than Hed’s Stinger 9.
Basics first: with a claimed weight of 1,630 grams without tires, and 2,170 grams with, the CXR80 is competitive with other wheels of similar depth — 60 grams lighter than the Hed Stinger 9 and about 90 grams heavier than Zipp’s 808 Firecrest.
The rims are fat, 28mm at their widest point, which falls about a third of the way down the rim from the brake track. The brake track itself is 27mm wide, necessitating narrow pads with certain brakes, just as most of today’s wide wheels do. Between the brake track and tire are grooves for a removable rubber strip designed to improve airflow.
The 16 stainless steel, double-butted, bladed spokes used in the front wheel are matched to 20 of the same on the rear. The hubs use a carbon shell, aluminum axles, and large, fully adjustable bearings. The flanges are thin and smooth, set wide in an effort to increase stiffness, and spoke nipples are external to aid in serviceability.
The wheels are available as tubulars only, with no immediate plans for a clincher version.
But the wheels themselves are only one part of the puzzle, Mavic says. The key to the CXR80s impressively low drag figures (more on those later) is a system-based approach. Just as it pushed rim/spoke/hub system integration in the 1990’s, Mavic is now focused on the rim/tire system interface, claiming that the transition between the two and the overall shape of the system as a whole are areas ripe for significant aerodynamic improvement.
Wheels are unique in that the leading edge becomes a trailing edge as the rim rotates, and so aerodynamics needs to be addressed in both directions. Without control over the tire, only the trailing edge of the front of the wheel and the leading edge of the back of the wheel can be controlled. Mavic set out to control both leading and trailing edges at the front and back of the wheel.
To that end, Mavic split this system into three parts: first is the wheel itself, detailed above. Second is the tire, which is shaped to match the wheel profile, and third is a small rubber strip called the CX1 Blade, which fills out the remaining gap between tire and rim.
With all this in mind, Mavic developed a specific tubular tire, the Yksion CXR. It is 23mm wide — wider than one might expect out of a tire designed with a focus on aerodynamics, in fact.
The company says it could have designed around a 21mm tire and made the system a tiny bit more aerodynamic, but that sponsored teams and riders requested the 23mm size to improve cornering and comfort.
The concept, according to Mavic’s road product manager, Maxime Brunand, is to use the tire itself to create the preferred profiles, both when a specific portion of the wheel is the leading edge (front of the wheel) and trailing edge (back of the wheel).
When the tire is leading, the CXR80 rim and tire fit a NACA 0024 profile. When the rim is leading, and the tire trailing, the system fits a truncated NACA 0011 profile.
Translated into English, that means Mavic has designed the rim/tire unit to reflect known low-speed aerodynamic shapes both when air hits the front of the wheel and when it exits out the back.
Other brands — both Bontrager and Zipp, for example — sell tires ostensibly designed to perform well with their wheels. But Zipp’s Tangente uses the casing from a third-party tubular manufacturer, and most of Bontrager’s aero tire efforts have been focused on clinchers. Mavic has, as of now, the only fully integrated system.
Mavic says the tire tread itself, which alternates between short parallel lines and small dots on the shoulder of the tire, is designed to induce turbulence, helping air stay attached to the rims for longer.
The CX01 Blade, often referred to as the “link” by the Mavic marketing department, is a slender rubber strip that fills the gap between the round tire profile and the top of the brake track. The goal is a smooth transition and specific shape between tire and rim.
The strip itself is not yet approved by the UCI (thanks to Article 1.3.004, which requires any technical innovation to gain approval before use in competition), but data from Mavic suggests it is worth about 1.5 watts at 50 kph, and that the wheels are still faster than their competition even without it. We can’t see the UCI approving what is quite clearly a non-structural fairing, but that shouldn’t stop amateur racers or triathletes from using the strips, which can be easily removed and re-installed.
As part of the CXR80 launch, Mavic brought a collection of representatives from the international cycling press to its primary wind tunnel test facility in Geneva, Switzerland, and performed wind tunnel testing in front of us.
The engineers made it clear that the protocol used was not exactly the same as is used in most of their testing, with fewer yaw angles tested due to time constraints, but the slightly revised protocol appeared sound nonetheless and the figures matched up with those provided from previous Mavic testing.
On the blocks were Mavic’s older CC80 wheels, a first-generation CXR80 set, the new CXR80 without its rubber blade, new CXR80 with the rubber blade, and Zipp’s 808 Firecrest.
All the Mavic wheels had Yksion CXR tires, while the Zipps had 21mm Tangente tubulars, as recommended by Zipp. All wheels were tested in a complete Cervélo P5 time trial bike without rider.
As with any manufacturer testing, published results should be taken with a grain of salt. We saw testing in only one frame (the interaction between frame and wheel can have a dramatic impact on results), the competition had only one tire available, which may not have been its fastest combination, and we were in the tunnel Mavic used to develop the CXR80.
The purpose-built balance used by Mavic adds an extra parameter, too: it measures watts needed to keep the wheel spinning. This figure is added to the normal drag figure tested in other tunnels.
Despite these caveats, the results were intriguing.
Most obviously, Mavic seems to have moved its stall angle out to a rather incredible 17-18 degrees yaw, three-to-four degrees further than any other wheel currently on the market. Zipp, Hed and Enve all sit around 14 degrees both in their own testing and in independent tests, varying slightly depending on the frame in which they are tested.
Once a wheel stalls, drag skyrockets, and as it does so, the wheels become much less stable. So despite the fact that Mavic and others have done extensive real world testing that shows that the average rider spends less than two percent of his or her time at such extreme wind angles, higher stall angles are still the goal of most aero wheel manufacturers. They add stability and speed.
Interestingly, the Mavic testing showed the Zipp 808’s stalling around 10-11 degrees, lower than the company’s own figures. Whether this is due to differences in protocol, influence of the bike, or something else entirely is impossible to know. So, again, results here are to be taken with some caution.
Since the UCI will likely ban the CX1 Blade strips, looking at the CXR80 without them is relevant as well. In Mavic’s testing, the non-strip wheels stalled out at 14-15 degrees, much closer to parity with the numbers we’re used to seeing from a set of 808 and Stinger 9 wheels.
And, at the much more common 0-10 degree yaw angles, the strip didn’t appear to do much at all, worth less than 0.10 newton. The CXR80s without the strip were still faster than the 808s until six-to-eight degrees, where the two match up briefly before the Mavics pulled ahead again.
We had an opportunity to ride the CXR80s, with the blade strips, for 65 relatively flat kilometers on Sunday. Sadly, winds were light and rains were sometimes heavy, so we ended up both very wet and without a real solid idea as to how the wheels perform in heavy crosswinds. We’ll have a pair soon, though, so keep an eye out for a full ride report with that particular performance metric.
Having ridden the older CC80s a bit over the last few months, the experience is completely different with the CXR80. They feel lighter (and they are), and a bit stiffer as well. The Yksion CXR tire rides better than the previous Yksion tubular, and corners better as well, though I would have preferred about 10psi less once the rain started coming down.
Where the CC80 felt like a time trial wheel, a bit slow to get going but fast in a straight line, the more sprightly feel of the CXR80 puts it more closely in line with the venerable 808 and Stinger 9 — better for flatter crits or road races, and as at home off the TT course as it is on. Mavic has a much better all-around wheel, now.
I did have one issue with the CX1 Blade strip, near the end of the ride. Due to my own inattention I rode through a rather massive puddle, four-to-five inches deep, and the water appeared to blow the right strip straight off the rim. Mavic says that in a year of testing they have never seen this happen and that it was likely caused by the frequent installation and removal of the strips on our test wheels over the last few days, which had stretched them out. They also assured me that had the strip tangled up in anything it would have simply broken rather than sent me face-first into French tarmac. I have to say that the event did certainly seem freakish, and as long as riding through rivers is avoided it wouldn’t weigh heavily on my mind while out on the road.
We’ll hold off final judgment until we have more time on a pair, and perhaps get them in the wind tunnel ourselves. But it is clear that overall, Mavic has developed a solid return to the crowded arena that is the aero wheel market. Price has not yet been set, but availability is slated for later this summer.