Austin Tri-Cyclist Blog

Showing posts with label Aero wheels. Show all posts
Showing posts with label Aero wheels. Show all posts

Friday, July 26, 2013

Mavic CXR60 Review

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


Thursday, April 26, 2012

2012 HED Jet Wheels
World Champion Clinchers



By Jack Mott

It has always been "known" that if you want serious race wheels, you need tubulars. They roll smoother, handle better, can tolerate higher pressures, are lighter, and spin up better. All of these things have been basic truths of bicycle lore for decades. For those of us who would prefer not to scrape glue off of a rim when we get a flat, we have good news. Time trial specialist Tony Martin recently ignored these myths and rode a set of HED Jet clinchers to victory, defeating the legendary Fabian Cancellara to become world time trial champion in 2011.

Clinchers just as good as tubulars? A tough pill to swallow for most, even if Tony Martin says so. But the arrival of top notch clincher tires, latex tubes, and new clincher wheel offerings from HED, Zipp, and others has made it a reality whether the old guard believes it or not. The newest iteration of the HED Jet line brings improved aerodynamics and reduced weight, allowing you to have your cake and eat it too – you can change tires easily, but go just as fast.

HED's Jet line has always offered an affordable yet fast and high quality alternative to more expensive brands like Zipp, as well as the convenience of clinchers and aluminum brake tracks. The Jet wheels are built out of conventional metal rims, with the aerodynamic shape being created from a thin carbon fiber fairing. This means the wheels handle just like ordinary wheels and share the reliability and ease of maintenance of normal wheels, but cut through the air with a lot less drag. No more picking tubular glue off the rim, no more changing to carbon-specific race pads, just throw the wheels on and race.

2012 HED Jet Features



Improved Aerodynamic Shape
NEW for 2012
- The JET line gets a new shape, noticeable at first glance as the inside edge of the rim is much meatier. This has been the latest trend in aero wheel offerings, said to provide less drag and better stability in crosswinds. HED claims that the new shape gives the JET the same aerodynamic performance as their tubular Stinger line.


Unidirectional Carbon Fiber Skin
NEW for 2012
- The new unidirectional carbon is lighter and stronger, allowing for the new aerodynamic shaping, as well as reducing the weight of the skin by up to 54 grams. Above, you can see a closeup shot of a 2012 Jet 6 on the left compared to a 2011 Jet 9 on the right. Notice the thicker inner edge and different carbon style. Click for a closer view.

C2 Wide Rims - Jet Wheels continue to have an extra wide rim, which can help to improve handling and overall aerodynamic performance when the wheel is equipped with 23mm or wider tires. Road racers absolutely benefit from this feature, as they almost always run 23mm or wider tires. Triathletes and time trial specialists should keep in mind that even with these wide rims, narrower tires are still generally a faster option for races against the clock. Click the picture to see a closeup view of how a Zipp Tangente 23mm tire mates up with the wide rim on a Jet 6. Notice how the tire doesn't bulge out past the rim itself, for cleaner airflow.

Aluminum Brake Track - Few other aero wheels of this caliber offer the feel and convenience of a standard metal brake track. No longer do you have to engage in a ritual of brake pad swapping, or pray that it doesn't rain. These rims brake just like your training wheels, no special pads required.

Clincher Convenience - Got a flat in the middle of a stage race? Want to switch to a different tire because of rain? Can't resist the urge to train a bit on your race wheels? With tubular race wheels you are out of luck, with clinchers, just change the tire! Put on a super narrow, delicate tire for an olympic tri, and put a wider more durable one on for a rainy ironman. Tire selection is such a key part of overall bike performance that this can be a huge benefit.

Flamme Rouge - In the past you had to pay extra for the lightweight Flamme Rouge feature, but now most Jet wheels come standard with these beautiful carbon hubs that save a bit of weight and look pretty sweet.

Customization - HED can build wheels to suit your needs. Larger athletes can get stallion builds with extra spokes, an array of custom colors are available, and most of their wheels can be built with a Powertap hub upon request. Other options include track versions, 650c versions, and even wheels for recumbents. HED is even nice enough to ship their wheels with stickers that peel off cleanly and easily for those who prefer the stealth look.

Snapple-ATC's Kat Hunter will be on HED Jets for the Tour of the Gila 2012!



Aerodynamic Comparison

The following is a compilation of data from the HED Website for their 2012 Jet Clinchers. This is marketing data so use it at your own risk. It may be useful in comparing the relative differences between the HED Wheels, but these numbers are not comparable to wind tunnel results from other sources, as protocol details (tire choice, tunnel calibration, etc) could be completely different. Yaw angle is the angle of the wind as it hits the wheel. Very fast riders or windless days will be at lower yaw angles. Slower riders or very windy days will be at higher yaw angles. As a rough rule of thumb, each 50 grams of drag will save about 0.5 seconds per kilometer, or 20 seconds over 40k on a flat, straight course.

The HED Jet Lineup

HED currently offers the Jet lineup in a variety of sizes from shallow to all-out disc wheels. All wheels ship with skewers, rim tape, and valve extenders. Stop by ATC and give them a try!

ModelDepthWeight
front/rear (g)
Price
front/rear
Pic
Jet 4
Flamme Rouge
46mm723/920$900/$1000
Jet 5
Express
54mm754/927Set $1500
Jet 6
Flamme Rouge
60mm724/936$900/$1000
Jet 9
Flamme Rouge
90mm895/1074$950/$1050
Jet Discn/a1300$1150
Jet Disc
Flamme Rouge
n/a1210$1450