For triathletes – the concept of non UCI legal has started to become common; at least when it comes to bike frames. At this point Felt, Trek, Specialized and Cervelo all offer either complete frames or frame additions that are both extremely fast and completely illegal in UCI sanctioned (non-triathlon) events. But frames are usually where the discussion ends – yes there are a few bottles and other bits that will make your setup non-legal, but it isn’t really something that major manufacturers have gone out of their way to do. However, it appears that is all about to change. Meet the Mavic CXR 60, a wheel \ tire combination that starts out as a UCI legal 60mm wheel, but when you add Mavic’s CX01 Blades, they lose their legality and gain a new found ability to cheat the wind.
Wheel \ Tire System
Mavic is one of a growing number of wheel manufacturers that believe the wheel is only one part of a complete wheel and tire system. That from initial research to final production, one has to consider the entirety of the wheel and tire system. Much of this belief is due to Mavic’s data, saying that the tire represents up to 85% of the total frontal area of the wheel. Therefore, only when the tire and wheel together create a unified aerodynamic surface, can the optimum system be created.
Mavic has also worked under the knowledge that the wheel interfaces with the wind not once, but twice; at both the front leading edge, and the rear trailing edge. Mavic’s science says that the first interaction is 60% of total wheel drag while the rear of the wheel accounts for the final 40%. To take all of this into account, Mavic ended up needing to use not one or two, but four different components to build the CXR system.
The system starts with the wheels. Mavic bucks the trend of full carbon wheels and has stuck with a carbon fairing bonded to an aluminum rim. The downside to this is weight. We measured the wheels weighing in at 1986g (886g/1082g respectively). The benefit is incredible braking performance, made even better with the addition of Mavic’s own Exalith braking surface. Mavic claims 18% shorter braking distance in both dry and wet conditions. We can state quite certainly that these wheels provide some of the strongest stopping power we have encountered to date.
The next two components are the tires. Mavic is not the only tire company making independent front and rear wheels (Continental with their Attack & Force come quickly to mind) but they are one of the few that do this as part of a complete wheel / tire system. Upfront you have GripLink and out back you have PowerLink. Both tires feature dual compound construction, where the contact patch and sidewalls use different rubber compounds. GripLink is designed to give the highest amount of control possible on the road and uses a slightly softer compound on the contact patch. PowerLink is designed to help you put down all the power you can. To that end, the rear wheel uses a slightly stiffer rubber. The patterning on the outside of the tires is not there for grip—as some would believe—instead it is there to create a boundary layer and keep the laminar airflow around the wheel. An additional note: Independent testing (http://bikeblather.blogspot.com/2013/08/even-more-crr-resultsand-another.html) does claim that the rolling resistance of the CXR60s is in line with many of the other major tires out there.
The final component is the CX01 Blades. The blades server to bridge the gap between wheel and tire and create a single, uniform airfoil. By bridging the gap, Mavic attempts to eliminate the generation of turbulent air from the gap that forms between the lip of the brake track and the curve of the tire as it comes in to hook on the inside of the rim. Other companies have sought to do this via the creation of wings on their tires (Bontrager R4 Aero), but Mavic’s solution is unique (and also very UCI illegal). The blades are built from a solid plastic strip covered by flexible rubber and weigh in at 22g a piece (you will need two per wheel). When installed, it is almost impossible to discern where the tire ends and the wheels begin.
The complete system sells for $2,750. For that you get the wheels, a set of tires, blades, wheel bag, and all of the standard equipment you have come to expect when purchasing new wheels (skewers, tape, etc…). If (when) you need to replace the tires, each one retails for $84.95 (but does include a set of blades). The blades themselves are available as a set and go for $30.
So why did Mavic go through all this trouble? To create not just the fastest wheel system possible, but also one they claim is also one of the world’s most stable. Mavic has modeled the entire system, and the wheels specifically on the classic NACA profile. After spending so much time with the toroidal shapes that have become so common, it is almost jarring to see the return to the NACA profile.
In a SlowTwitch monitored shootout, Mavic’s CXR 80 (the 80 mm version of the 60 with a similar shape that makes use of the same tires and blades) beat out some of the best in the world (including the Zipp 808 FireCrest, Bontrager Aeolus 7 and HED Stinger 7). While we often lend healthy skepticism to any manufacturer claims, we cannot help but be impressed with the fact that Mavic brought in SlowTwitch to monitor the results.
Mavic claims that the edition of the blades, and the resulting reduction of turbulent air, also provides a significant benefit to stability. In the chart below, Mavic’s contention is that the smoother line of the CXR 60 implies a more consistent ride as the winds impact the bike.
So what does this all add up to? For the CXR 60, Mavic claims 3.2 watts saved against their closest competitor (without stating who that competitor is) resulting in a 9-second improvement over 40km and 40 seconds in an Ironman bike split. When the deeper CXR 80 is used, Mavic claims that in a performance simulation on the Kona World Championship course, a rider would save 2 minutes and 28 seconds by riding a set of CXR 80s versus Zipp 808s.
We started this review with a bit of trepidation. Of all things, the blades made us nervous. We had experimented with the blades at a number of product events, and had a bit of difficulty getting them on and off. We started to have fears that if you needed to change a flat come race day, you would end up leaving the blades on the side of the road. The good news was that this fear was completely unfounded – after a small amount of practice, getting the blades on takes less effort than mounting a tire.
From a ride perspective, the wheel spins up quick—quicker than one might expect due to their weight. We attribute that to the quality of the wheels’ hubs. And as we said before, these wheels are incredible stoppers. Exilith is everything Mavic claims it to be and produces an almost unreasonable amount of stopping power. If you are riding these in a pace line, and the rider behind you is riding something different, make sure to give them as much warning as possible when you plan to brake hard.
Unfortunately we have not had a great chance to validate the stability claims of the CXRs. Most of our recent rides have been in fairly calm winds. And because of this, we have not been able to validate the cross wind claims of Mavic. In fairly calm winds we have found the wheels to be excellent cross country haulers. They require little or no adjustments as you encounter long, straight stretches of road.
Our one current concern is how the tires react to wet conditions. On one of our last rides before writing this, we rode on roads that had spent the night being drenched. The results were roads soaked in water and other road grime. Over the last 10 miles of our 50 miler, the tires (both front and rear) started to lose more and more traction—especially when we were encountering hard (90°) turns. By the end of the ride, every turn was being treated with kid gloves. The traction was so bad that at first we assumed we had picked up some oil on the tires, but on inspection could not find any. Additionally, we did notice that the transition from contact patch to sidewall on the tires is more abrupt than on most wheels due to the use of two different compounds. We currently suspect that that abruptness, combined with road grime, is what contributed to the traction issues in wet conditions. However, we need to spend some more time in those conditions to know for sure.
Well as is always the case with our long term reviews, this is just the first step in getting to know the CXRs. Up next we will continue to see how the wheels perform in a variety of conditions. We hope to encounter at least one blustery day to see how Mavic’s claims stack up to some South Florida crosswinds. We are also looking to encounter another day of rain to see if we experience stability issues once again, or if it was just a onetime occurrence. Finally, we want to spend some time climbing with the wheels to see how the weight affects them going up, and how the braking does going down.
If you have any questions or feedback – make sure to send us leave a comment below or connect with us via Facebook, Twitter, or email. We conduct our reviews in two parts so our readers can help us adjust our test plans to get the answers you’re looking for.