Friday, July 26, 2013

Mavic CXR60
So aero they made a custom tire

by Jack Mott


For a little over a year, the new breed of Mavic wheels has been on the market in the form of the CXR 80, a deep wheel with a bunch of unique features that has proved to be an excellent performer. The CXR 80 was the TT wheel of choice for the Garmin-Sharp pro cycling team, and has also been ridden with success in the local bike racing scene, even in crits. However, it's available only as a tubular, and is deeper than some people are comfortable with. Now a medium-depth version of the CXR line is here, the CXR 60, and it comes in clincher too! The key features of the CXR line of wheels include:

New Aerodynamic Shape



Mavic's CXR line takes a unique approach to wheel shape. Unlike the rest of the industry (which somehow simultaneously adopted "U" shaped rims), Mavic uses a combination of custom tires and a "blade" that fills in the space between tire and wheel to have complete control of the entire wheel-tire shape. If Mavic's wind tunnel results are accurate, this gives them a sizeable aero advantage over other wheels.


Downsides to this approach include a reliance on Mavic's custom tire, which may or may not have great rolling resistance to go with its excellent shape. If the rolling resistance is not good, it can more than offset the aerodynamic advantage. This is of particular concern in the tubular versions of the wheel, as the rolling resistance is not very good with that tire. Tom Anhalt has measured the rolling resistance of the Mavic clincher tire and thankfully found it has excellent rolling resistance, details here.

The other downside is dealing with the blades. The CX01 blade snaps into the rim after you install the tire. The process is quite simple, but would be an extra step to deal with when changing flats on training rides. On the other hand, you don't have to use the blades on training rides; you can save them for race day. Additionally, you need to take care that the brake pads are adjusted properly, or they could grab the blade when you apply the brakes. There have been a few reports of blades coming undone during bike races, possibly due to contact with other bikes. They can then get wrapped up in your hub and end your race. The blades might best be saved for time trials and triathlons, where bike-to-bike contact is rare.

While Mavic literature insists that the blades are only compatible with the Mavic tire, during our testing we used it along with the Continental GP4000S and experienced no issues or wear on the sidewall. The aerodynamic fit seems to be excellent as well (click to zoom):

CX01 Blade Fit with Mavic Tire
CX01 Blade Fit with GP4000S Tire

However, given the good rolling resistance of the Mavic clincher tire you may want to stick with it, especially up front.

Exalith Braking Surface

The braking surface on the clincher version of these wheels is a special metal surface that Mavic calls Exalith 2. It has a directional texture, and is designed to work with a specific Mavic Exalith brake pad. The braking power and modulation on this is excellent, especially in the rain due to the texture feature. Our resident Cat 1 cyclist tester said she thought it felt better than her standard aluminum rims. While other racers get stressed out if there is rain in the forecast, you can remain calm and focus properly on your race, a nice advantage. The downside is the necessity of using the Mavic Exalith brake pad, which you may have to swap on and off if you use other wheels for training. In a pinch, other pads will work fine, but the Exalith surface seems to tear them up pretty quickly. You also must take care to orient your front wheel in the proper direction for optimum braking. We did test the braking with the wheel installed the wrong way around, however, and it still worked well.

The tubular version of the wheel uses a more traditional carbon braking surface.

Aero Tuned Hubs

The hubs on these wheels clearly have some aerodynamic thought put into them. The central section is as small as possible, and the flanges are also kept small and covered with smooth aero-shaped caps:



Real World Testing

Road testing revealed what we expected. Mavic wheels are very well built! There were no issues or drama under hard cornering or acceleration, and no flexing to cause the rear wheel to rub when pushing sickwatts up steep hills. We tested the wheels in a Cervelo S5 and a Litespeed C1 and found no clearance issues on either. Our resident Cat 1 cyclist Kat Hunter gave them a thumbs up, noting the exceptional braking performance. Meanwhile, our Cat 3/triathlete was able to decimate the local Strava scene in his neighborhood. Testing during windy days showed the wheels to be stable and predictable.



We noticed that the outer width of these wheels is quite wide, a bit wider that our HED Jets, in keeping with the current trend of sizing the wheel to match the width of 23mm tires. However, much of that width is used by the channel that you snap the CX01 blades into. The actual width of the rim from the tire's point of view is actually quite narrow. Rather than shaping the tire to fit the rim via extra wide bead hooks, Mavic uses the blade to provide a seamless tire to wheel transition. This design does make it a bit harder to work your tire onto the wheel. Below you can see the a blade, still snapped in place on the left, and the groove that the blades snap into on the right:



The construction of the clincher wheels is similar to HED Jets, with a carbon fairing attached to an aluminum rim. Mavic also applies a carbon fiber "cap" on top of the metal rim, however. The only exposed metal is the black Exalith braking surface and the black spokes.

Pricing and Availability

The CXR 60 will begin hitting Austin Tri-Cyclist (and other stores probably) in mid August.  Pricing info will be in soon. Each wheelset includes a bunch of nice extras:
  • BR601 quick releases
  • Rim tape
  • Wheelbags
  • Exalith brake pads
  • Valve extenders
  • Multifunction adjustment wrench


2 comments:

  1. an Aeroweenie would know that you'll update when the data ARE in, not when the data is in ;)

    ReplyDelete
  2. That would be a grammar weenie!

    ReplyDelete