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.Pages: 1 2 3 4