TECH NEWS: RBA TEST: ROLF PRIMA ARES 6
October 5, 2012


Times are changing in the wheel market, and Rolf Prima knows this as well as anyone. What was considered an aerodynamic rim depth less than a decade ago hardly even comes up in the conversation these days. Rolf Prima’s versatile Vigor aluminum clincher wheels have served the peloton well for years, offering 32mm of depth at a sub-1500-gram weight. But as the demand for deeper clincher wheels pushes on, Rolf Prima had to move beyond what the all-aluminum rim could accomplish in regards to depth versus weight. For 2012, Rolf Prima entered the fastest-growing wheel segment—full carbon clinchers. They will start by offering three depth options: the 80mm Ares 8, 66mm Ares 6, and 46mm Ares 4.

THE TECH
Like all Rolf Prima wheels, the Ares 6 uses the company’s patented “paired spokes” and “differential hub flange diameter” design. The paired spoke concept allows for a spoke tension higher than what many other wheels can achieve with a traditional lacing pattern, all the while using fewer spokes than most conventional designs. Placing the left and right pulling spokes next to each other offsets their pulling pressure, allowing the Ares to have as few as 16 spokes to reduce weight and improve aerodynamics.

The other proprietary feature Rolf Prima uses is the differential hub diameter. By using a stiff hub shell that transfers torque to both the drive side and non-drive side, this design allows pulling spokes from both sides to engage rather than just the drive-side spokes of many designs. Rolf Prima says the design allows for better power transfer since more spokes are engaged in pulling. For Rolf’s introduction into carbon clinchers, they went with one of the most advanced full-carbon clincher rims available, one that is manufactured by Reynolds. Since full-carbon clinchers are much more susceptible to rim failure due to heat buildup from braking than a wheel with an aluminum brake track, or a tubular, special brake pads and resins are used to reduce the temperatures that can reach as high as 300 degrees Fahrenheit. To deal with this intense brake heat, the rims use a carbon weave on the brake track called “CTg,” which helps keep temperatures below glass transition (the rim’s heat failure point) when used in conjunction with the included proprietary brake pads.


PERFORMANCE
Climbing
The Ares 6 skews more to an aerodynamic advantage rather than being for climbers. For shallow climbs and rollers, the 66mm wheels carry their speed and accelerate well, but for true climbing, most riders would be better served with the approximately 200-gram-lighter Ares 4s.

Road comfort
Sixty-six millimeters of carbon doesn’t manifest itself into vertical compliance too well, but if it’s of any consequence, the speeds we were holding on the flats due to the rims’ sail effect had us rolling across the top of smaller bumps rather than hitting each one.

Cornering feel
The Ares 6 would make for a fine criterium racing wheelset since it gave us confidence in the corners by staying unwavering from the line we set. The front hub flanges are spaced as widely as you can go while still allowing for fork clearance, which definitely seems to aid lateral stiffness.

Braking
The rims’ CTg brake track provided good modulation without a grabby feel. We’ve always been impressed with the braking from Reynolds rims, and these particular rims are bridging what used to be a large gap in braking performance between carbon and aluminum rims.

Windy conditions
We’ve spent a fair amount of time lately on wheels from Zipp, Bontrager and ENVE—all with a wider, rounded nose, unlike the sharp profile of the Ares 6—and the difference in crosswind handling is noticeable, with the Ares 6 being blown around more than the aforementioned wheels of a similar depth.

Durability
To start with, the hubs are made in the U.S. Also, the rear hub uses a titanium freehub body, which holds up better than aluminum due to its hardness. If the spokes were to ever need replacing, they are a standard J-bend that most bike shops would have in stock. The rims themselves are new to Rolf Prima, but we’ve been riding a similar pair that have logged a couple thousand miles without the slightest hitch. And equally important as the components that make up the wheel is who, or what, builds it. Rolf Prima hand-builds all their wheels in Eugene, Oregon.

THE VERDICT
Taking the plunge into the full-carbon clincher market was essential for Rolf Prima to make that next step in furnishing a wheel option that provides good aerodynamics at a reasonable weight with the versatility of a clincher. The unique design of the Ares 6 stands out aesthetically in a market already loaded with options, but it’s not only aesthetics that sets Rolf Prima apart. The paired spoke design produces stiffness equal to many of the 20-spoke wheels out there, but with four fewer spokes, ultimately improving aerodynamics. The Ares 6 is best suited for flat-to-rolling terrain or time trials, while the 46mm-deep Ares 4 might be a better option for an all-around, everyday wheel since it’s lighter and won’t be impacted as heavily by crosswinds.

Price: $2299
Weight: 1703 grams, plus 90-gram quick releases
Rim depth: 66mm
Rim width: 21mm
Spoke count: F-16 /R-16
Spoke type: Aero stainless steel
Spoke pattern: F-radial/R-1x nondriveside and 1x driveside
Notes: Available for Campagnolo and Shimano/SRAM. Includes quick releases, pads and valve extenders.For more info: Rolf Prima

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