60mm-tall wheels𝐆 in both clincher and tubular versions
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Mavic Cosmic Carbone CXR 60 T tubular wheelset (Image credit: Jeff Jones/BikeRadar.com)
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The Geneva wind tunnel is situated below this brid🃏ge. It's not easy to find space to build wind tunnels and this was a cheap and good option, due to the climate stability in🃏side (Image credit: Jeff Jones/BikeRadar.com)
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The Mavic Cosmic Carbone CXR🀅 60 C wheelset. They're the clincher vers🤡ion. (Image credit: Jeff Jones/BikeRadar.com)
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The two tyre and rim profiles for the CXR 60 C and T models. There are subtle differences in shape between thꦺem (Image credit: Jeff Jones/BikeRadar.com)
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The CXR 60 C outperform the tubulars slightly at lower yaw angles until they stall 💖at 15 degrees (Image credit: Jeff Jones/BikeRadar.com)
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Comparison between CXR 60s (L) and Zipp 404 FC (R). 2 = 5 degrees of yaw; the numbers in the column neꦍxt to that are drag. In this run the Zipp is slightly better at 5 degrees than the CXR 60 but that soon changes when you hit 4 (10 degrees), the stall angle for the Zipp (Image credit: Jeff Jones/BikeRadar.com)
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The Zipp 404 ready to be tested (Image credit: Jeff Jones/BikeRadar.com)
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The Yksion tyres feature rough edওges to help the air keep to laminar flow around the tyre and rim (Image credit: Jeff Jones/BikeRadar.com)
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A useful comparison graph between the varioไus CXR models. Using the average weighting law, the CXR 80s are best but only by 0.4 W compared to the 60 T and 1.4W to the 60 C (Image credit: Jeff Jones/BikeRadar.com)
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The graph of lateral force vs stability seeminꦛgly shows the Mavics behaving fairly predictably as wind angle increases, whereas other wheels don't. But they didn't measure steering torque only lateral force on the wheels. We would be very wary of saying these results applied in the real world (Image credit: Jeff Jones/BikeRadar.com)
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Mavic say their Cosmic Carbone CXR 80s save 6.4W (15sec in 🐈40km at 50km/h) on average over Zipp 808 and Hed Stinger 9 (Image credit: Jeff Jones/BikeRadar.com)
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Mavic's wheels tested agains𝓀t others on neutral ground at the San Diego wind tunnel. The Bontrager Aeolus 7 pips them at -15 degrees but the Mavics win everywhere else (🉐Mavic CC 80 is their Cosmic Carbone 80 model, which don't have the CXR profile so aren't as good aerodynamically) (Image credit: Jeff Jones/BikeRadar.com)
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Mavic say their Cosmic Carbone CXR 60 Ts save 6.3W (19sec in 40km at 50ꦍkm/h) on average over Zipp 404, HED Stinger 6, and Enve 6.7s (Image credit: Jeff Jones/BikeRadar.com)
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Mavic say their CXR 60 Cs save 3.2W o🉐r 9sec in a🧸 40km TT at 50km/h over Zipp 404s or HED Stinger 6s (Image credit: Jeff Jones/BikeRadar.com)
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Maviꦍc simulated how much Van Lierde would save in t꧒he Kona bike leg over a set of Zipp 404s, given average wind conditions based on 20 years of climate data (Image credit: Jeff Jones/BikeRadar.com)
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Frederik Van Lierde, who finished 3r🅠d in the Ironman world championships at Kona last year, gives his view on the Mavic CXR 80s (Image credit: Jeff Jones/BikeRadar.com)
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The ཧCXR 60 Cs have a rim strip and an Exalith braking surface. The tubulars don't possess this and won't give as good a braking performance (Image credit: Jeff Jones/BikeRadar.com)
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The spoke bed is snub-nosed but not quite as thick as a 40🎶4 (Image credit: Jeff Jones/BikeRadar.com)
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Mating the tyre to the rim and smoothing via a removable plastic strip means that Mavic can optimse the shape💟 of the whole wheel (Image credit: Jeff Jones/BikeRadar.com)
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The Cervelo P5💮 test bike on the rig in the tunnel (Image credit: Jeff Jones/BikeRadar.com)
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Jean-Pierre Mercat, head of Mavic🐠 advanced research, gets ready to rumble (Image credit: Jeff Jones/BikeRadar.com)
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Getting the wheels rolling via the mechanism built i🔯nto Mavic's balance (Image credit: Jeff Jones/BikeRadar.com)
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Zipp 404 Firecrest and Bontrager Aeolus wheels ready toไ be tested in the tunnel (Image credit: Jeff Jones/BikeRadar.com)
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The back end of the wind t🥀unnel in Geneva, that Mavic use extensively for product development (Image credit: Jeff Jones/BikeRadar.com)
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When you ri🗹de at an angle to the w♑ind direction, you experience drag force (FD) and lateral force (FL), among others. These are what Mavic measure in the tunnel (Image credit: Jeff Jones/BikeRadar.com)
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How the sail effect works. There is a small amount of po🗹sitive drag force when certain wind conditions are met. This definitely doesn't mean you don't have to pedal, think of it as a small boost in certain situations. (Image credit: Jeff Jones/BikeRadar.com)
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Mavic came up with this weighting law to average out the time typically spent at various yaw angles. They work out time savings for wheels using this a🐎verage (Image credit: Jeff Jones/BikeRadar.com)
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Mav🔯ic's on the bike anemometer to 𒁏measure all the different wind angles that the rider encounters (Image credit: Jeff Jones/BikeRadar.com)
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Front wheel drag tes♕ts vs complete bike. The trends and gaps are the same (Image credit: Jeff Jones/BikeRadar.com)
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A pair of🐼 CXR 80s vs a CXR 80 plus a Comet🦹e disk. The disk is better at higher yaw due to the sail effect (Image credit: Jeff Jones/BikeRadar.com)
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Wheels only count 🏅for 7% of the rider's drag but any saving is worth having (Image credit: Jeff Jones/BikeRadar.com)
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The rim strip is easy to clip on and off (Image credit: Jeff Jones/BikeRadar.com)
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CXR60 T (green) vs CXR60 C (brown) vs Zipp 404 FC (blue) vs Bontrager Aeolus (red). The CXR 60 clinchers are the best up to about 15 degrees, then they stall and the CXR 60 tubulars are better. The Zipp 404s are good between -10 and 5 degrees, then they stall badly, costing as much as 20W at 50km/h. The Bontragers have a good stall profile but a💧re about 5-6W slower than the CXR 60 Ts at all angles (Image credit: Jeff Jones/BikeRadar.com)
This article originally published on
Mavic claim their new Cosmic Carbone CXR 60 wheels can beat out aero titans such as the Zipp 404 in the wind tunnel at certain yaw angles. The CXR 60 follows on from the desiꦦgn of Mavic’s first aero wheel, the , wಌhich was introduced last year as part of a wheel-tyre system.
As with the CXR 80s, the 60mm-tall CXR 60 wheels feature snap-in 'blades' that smooth the transition between the tyre and wheel. The blades' func🐽tion is purely aerodynamic. However, while the 80s are tubular only, the 60s come in clincher anꩲd tubular options.
The €2,000 CXR 60 clincher set will include the wheels, Mavic tyres, blades, skewers and bags. Claimed weight is 1,800g, with another 195g for the tyres. The €2,200 CXR 60 tubulars have a claimed weight of 1,60🍸0g for the pair, and the tyres are 240g a piece.
The firꦯst wheels are expected to begin shipping in July, with full availability by September 2013.
Mavic’s wind tunnel
Mavic do their aerodynamics testing in the C𒉰MEFE hepia wind tunnel in Geneva, Switzerland. The University of Geneva operates the tunnel for a variety of tests, from optimising the French downhilಌl skiing team to modelling pollution fallout across cities.
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Mavic are the only cycling company with access, though, and provide their own engineers, aerodynamicists and even a force measuring balance to keep costs down. As a result, they were able to spend 18 days in the tunnel in 2011, and 28 in 2012 &ndꦬash; around 1,000 hours in total – to develop and test their wheels.
Mavic al💃so used a bicycle mounted weather vane to measure and record wind direction during any given ride. The wind direction changes a lot and Mavic wanted to get an idea of the distribution of yaw angles. They gathered plenty of data and came up with a weighting law to clump the aero savings at various yaw angles into a single number that's easier to understand, and hopefully realistic.
We have a feeling we'll be seeing a lot more from Mavic in the future, as they've quickly 𒁏closed the gap to their competition thanks to the convenience of having a wind tunꦜnel almost on their doorstep.
Top-line figures and judgements
While Mavic claim the CXR🍌 80s outperform e🐈very wheel they've tested, the CXR 60 clinchers and tubulars are close to each other.
Like many manufacturers, Mavic measured the drag of the wheel at a variety of yaw angles. Interestingly, the CXR 60 C (clincher) is better than the CXR 60 T (tubular) from 0 yaw (head-on wind) to about 10 degrees. This 💖is due to the slightly different tyre and rim shapes of the cജlincher and tubular.
When considering a weighted average of yaw angle💖s based on what a rider will typically experience, all three wheels were within 1.5 watts of each other. Mavic found that ♛the Zipp 404 Firecrest wheel did a bit better than the CXR 60 at 5 degrees, but not at 0 or at 10 degrees.
At a glance, we think the CXR 60 C seems like a go꧙꧂od bet over the CXR 60 T because:
*The metal Exalith braking is better than the carbon surface on the tubulars *They are cheaper by €200 *The tyres have better rolling resistance by 3-4w with a standard butyl (not lightweight latex) tube. Rolling resistance savings could be even greater with the latter *They are about the same weight as tubulars when you include the tyres *They have slightly better aerodynamics between 0 and 10 degrees *No glue is required!
A pro triathlete’s perspective
Mavic had Ironman World Championship bronze medalist Frederik Van Lierde on hand for the wheel launch,🥂 to talk about his experience on the CXR 80s, which he rode at Kona last year to his best ever bike split (4:35) and position (third) on a windy day.
&l🎀dquo;Last year, in September, I was here [in the Geneva wind tunnel] to do some testing with Mavic,” Van Lierde said. “I tested a couple of things, including position. One thing convinced me when I did the setup wiꦏth only one wheel, the CXR 80, at a certain yaw angle into a headwind: the wheel kept spinning. That was good technically and mentally.”
Van Lierde chose to ride the CXR 80 front and back at Kona, which can be notoriously windy. &ldquo🦂;I could stay in the bars the whole time, something I didn't have with other wheels,” he said. “For a course like Hawaii these are great wheels for all those kind of windy conditions. Previo🔯usly I was 10th to 15th in the bike; now I was fourth.”
Van Lierde said that, while he will always race a set of 80s, the CXR 60 is a great aᩚᩚᩚᩚᩚᩚᩚᩚᩚ𒀱ᩚᩚᩚlterna🌳tive for “people who are not sure about 80s”. Aside from the handling aspects of an 80mm wheel, there's also the fact that the 80s are tubular only.
Numbers and claims
When considering resistive forces acting on the rider and bike, aerodynamics are quite important. While rolling resistance doesn't increase with speed, aerodynamic drag goes up wit🔯h the square of speed. The power you need to overcome rolling resistance incre🧸ases linearly with speed but goes up with speed cubed for aerodynamic drag.
For their comparisons, Mavic ramped up the speed to 50km/h. Fo🔴r reference, the fastest-ever stag𓃲e of the Tour de France was won by Mario Cipollini at an average speed of 50.355km/h, and David Millar won the fastest-ever Tour time trial longer than 40km with an average speed of 54.361km/h over 49km.
Taking into account a weighted average of yaw angles, Mavic say their CXR 60ওs save 6.3 watts, or 19 seconds, over 40km when going 50km/h, compared on average to the Zipp 404s, the HED Stinger 6 and the Enve 6.7.
Tyres and NACA profiles
Mavic considered tyre and rim in developing their 💖whe🎃els, because the tyre is what sees the air first and affects the airflow.
The CXR 60 C and T use different sets of NACA airfoils. There are two pr🌟ofiles because each wheel hits the air twice, once in front (60 percent of drag) and once at the trailing edge (40 percent). The CXR 80 uses NACA profiles 0024 and 0011, the CXR 60 T uses 0029 and 0017, and the CXR 60 C uses 0027 and 0012.
The t♚yre tread patt꧒ern is also optimised for aerodynamics, to help keep flow laminar around the rim and tyre.
While the spokes and hubs are as slender as possible while maintai🔜ning high stiffness, Mavic have used their normal hubs, and haven't tried to optimise them for aerodynamics.
First ride review
BikeRadar are test riding the CXR 6꧋0s today, so will post a first ride review following that.
