RBA Test: Aero Wheel Comparison

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Welcome to the new age of carbon clinchers. It’s an age in which wheel manufacturers are investing as much-or even more-time and money into producing aerodynamic shapes for their clinchers than their tubulars. It’s an age in which some professional racers are even opting for carbon clinchers over the traditional, race-specific tubulars in individual tests of time. And most significantly, it’s an age in which manufacturers are now finely crafting carbon clincher rims that not only perform but can stand up to the rigors of daily use and abuse from the average cyclist. What follows is a comparison between three of the most advanced carbon clinchers currently on the market. All three are manufactured and built in the United States, and all three are also available in tubular versions, but each tackles the problem of pairing performance and convenience with a different game plan.

THE PLAYERS

First we have the Bontrager Aeolus 5 D3. On the surface it’s a straightforward, full-carbon clincher with matching front and rear profiles, DT Swiss hubs, and DT Aerolite spokes. But beyond the relatively standard specifications, the Bontrager’s most standout feature is its width. Ever since Zipp’s Firecrest design hit the market, various competitors have invested copious amounts of time and money into exploring the ‘wider is better’ philosophy. And to their credit, Bontrager seems to have come out swinging in that department, with 27mm-wide, 50mm-deep rims designed to be the ultimate all-around wheelset with an eye toward straight-line speed that doesn’t compromise handling.  

Next is the SES (Smart ENVE System) 3.4 clincher from Ogden, Utah’s ENVE Composites. Designed by noted aerodynamicist Simon Smart of Formula 1 race car pedigree (he worked with the Brawn and Mercedes-Petronas teams), the three-strong SES line has the same goal as the Bontragers-that is, to provide an ideal balance of aerodynamic efficiency and steering confidence. But unlike the Bontragers, with their matching widths and depths, the front and rear ENVE wheels feature disparate measurements, with the front possessing a 26mm width and 35mm depth and the rear sporting a 24mm width and 45mm depth.

Last but not least is Mad Fiber’s all new clincher. Venerated by cyclists, engineers and artists alike, Mad Fiber’s tubular wheels have been the talk of the cycling industry for the last two years. Now the Seattle-based company has released a clincher version, but with a twist befitting a company known for throwing out the rulebook. Rather than producing a full-carbon clincher, Mad Fiber’s alternative design involves an aluminum rim molded into their unique carbon-spoke configuration.

BONTRAGER AEOLUS 5 D3
Although Bontrager has brought several carbon clinchers to market in recent years, the Aeolus 5 D3 distinguishes itself as the brand’s entry into the ever-widening rim arena. A tubular version has been a favorite among pro riders on both the RadioShack-Nissan and Bontrager- Livestrong teams throughout the 2012 race season. And while that same tubular can be purchased at your local bike shop, the clincher version offers the tire-changing ease that most cyclists prefer for everyday use. The rim design was refined from literally thousands of CFD (Computational Fluid Dynamics) simulations, and the D3 designation stands for ‘Dual Directional Design,’ a reference to the similarly wide profiles of its leading and trailing edges. Both the front and rear rims have the exact same profile measurements (50mm deep and 27mm wide), the same as the tubular version, but hub specifications are different.

While the tubular Aeolus 5 wheelset is built with DT Swiss 180 hub internals and custom carbon shells, the clinchers are paired with DT Swiss 240 hub bits and custom aluminum shells. Bontrager’s D3 wheel line also includes the 90mm-deep Aeolus 9, 70mm-deep Aeolus 7 and 35mm-deep Aeolus 3 models, all of which are available in both clincher and tubular versions for 2013. Unlike Bontrager’s earliest carbon-rim efforts that were made in partnership with HED wheels, all of the rims in Bontrager’s Aeolus line are manufactured and assembled in the company’s Wisconsin factory.

ENVE SES 3.4
On the surface, ENVE’s latest wheelset is quite similar to the Bontrager Aeolus 5 D3. The carbon clincher rims feature a unidirectional carbon fiber design honed inside a wind tunnel, and they’re mated to DT Swiss 240 hubs with DT Aerolite spokes. But a closer look reveals far more differences between the two companies’ aero clincher offerings. While the Bontrager rims feature identical widths and depths, the ENVE front rim is 26mm wide and 35mm deep, while the rear wheel is 24mm wide and 45mm deep. ‘We tested all of our prototype wheels in the wind tunnel, but we mounted them inside a bike frame to better simulate real-world conditions and found that the front and rear wheels have different needs,’ says ENVE’s aerodynamicist Simon Smart. ‘In a frame, the rear wheel is shielded from wind more than the front wheel, for example. We optimized the front wheel around several fork designs, and then did the same thing for the rear wheel around the rear end of a frame, and we were amazed with the different results of what shapes worked best.’

The ENVE rims are all manufactured inside the company’s Ogden, Utah, headquarters. Three hub options are available for complete wheelsets: Chris King R45, DT Swiss 180 and, like our test pair, DT Swiss 240. The SES line also includes two wheelsets with greater depths (the widths are the same as the 3.4 set): 6.7 (front: 60mm deep; rear: 70mm deep) and 8.9 (front: 85mm deep; rear: 95mm).

MAD FIBER
When Ric Hjertberg and Max Kismarton released their Mad Fiber brand’s radical tubular wheel back in 2010, the entire cycling industry took notice. The wheel guru and the aerospace wizard believed that most carbon wheels on the market possessed an inherent flaw, namely that they were the end-product of utilizing a new material to build designs that were optimized for metal construction. Thus Mad Fiber tubular wheels became the embodiment of what Hjertberg calls ‘Carbon Optimized Design,’ an engineering process that takes advantage of carbon fiber’s unique properties rather than one that swaps out metal bits for carbon in a typical wheel design.

Now the young brand has ventured into the realm of clincher wheels. But instead of using carbon for carbon’s sake, Hjertberg and his team have carried on with their philosophy of material optimization. The Mad Fiber clincher, thus, is not a full-carbon clincher, but a hybrid construction consisting of an aluminum rim bed surrounded by a carbon rim and the company’s signature wideand- flat carbon spokes. The rim, spokes and carbon hub shells are custom-made inside Mad Fiber’s Seattle factory, with all of the pieces being bonded together during the manufacturing process. Like Mad Fiber’s tubular, the clincher is built with hub internals from White Industries and comes in two bearing options: stainless steel (tested) and ceramic.

THE RIDE
Neither using the most advanced materials in the world nor countless hours in the optimum conditions of a wind tunnel can replace the need for real-world testing. It’s outside on the roads and in the elements where wheels are ridden, raced and abused. And while all cyclists can benefit from advanced aerodynamics and safer carbon clincher technology, individual preferences for ride comfort, stiffness and price mean that no one wheel will suit every rider’s needs. These three wheels, in particular, were designed with a nod toward overall ride quality, as well as superior handling in windy conditions. With that in mind, each of our test wheelsets was mounted with Serfas Helix 23c tires and ridden for months over a slew of road conditions, ranging from pristine tarmac to pothole-stricken nightmare. Here’s how each performed.

Road comfort
Both the Bontragers and the ENVEs roll exceptionally well over most road conditions, and, relative to other carbon wheels of similar depth, both are quite comfortable during long days in the saddle. But neither the Bontragers nor the ENVEs can hold a candle to the Mad Fibers when it comes to road comfort. The latter’s wide carbon spokes feel downright flimsy to the touch compared to the DT Aerolites found on the other two, but Hjertberg’s non-traditional design yields the most comfortable ride in our comparison. Most light road chatter is all but eliminated, resulting in wheels that feel as if they’re almost floating over most rough road conditions. It’s truly a unique experience, but several testers remarked that when the Mad Fibers hit a large pothole, the ensuing thud caused greater trepidation than most any other wheels we’ve ridden. We attribute this to the Mad Fiber rim’s unique carbon layup, as well as the signature carbon spoke pattern.

Climbing
If the only thing we ever did with our bikes was climb mountains in perfect weather conditions, then we’d opt for the Mad Fibers. The Mad Fiber’s low weight, which is comparable to the ENVEs, combined with a buttery-smooth ride quality, makes them ideal ascending partners. For those who prefer a bit more stiffness in their climbing wheels for quick bursts of acceleration, the ENVEs are a better option. At 1620 grams, the Bontragers are the heaviest of our test wheels, making them the least desirable among the three for climbing.

Windy conditions
On the rare occasion of a straight headwind or tailwind, there was little discernible difference in handling capabilities between our three test wheelsets. But when even the slightest crosswind reared its ugly head, the disparities became dramatically apparent. It was no surprise that, with the shallowest depth among our three test models and separate profiles developed in the wind tunnel specifically to combat real-world crosswinds when mounted to a bike frame, the ENVEs proved the most savvy at handling windy conditions.

Despite their deeper profile, the Bontragers still provided steady handling on even the windiest of days. The Mad Fibers, on the other hand, feature a rather traditional V-shaped profile, a form that catches sidewind more easily than the contemporary wider and blunter profiles of the ENVEs and Bontragers. Still, the Mad Fibers aren’t what we’d call a handful on windy days, but they do require a bit more extra effort to corral their movement. Cornering The Mad Fiber’s spokes and hubs, while impressive to behold, don’t provide the same level of stiffness as the DT Swiss bits found on the Bontragers and ENVEs. As such, the same supple ride quality that makes the Mad Fibers comfortable over any stretch of road prevents them from attaining the same cornering prowess as the other two. Both the Bontragers and ENVEs feel firmly planted throughout, even during the fastest directional changes, with the Bontragers in particular proving to be exceptionally stiff upon exiting turns and transitioning into sprints.

Braking
Braking performance remains the most contentious issue regarding carbon clinchers, but we’re happy to report that the latest offerings from our three test brands represent a significant evolution in stopping power and modulation among carbon clinchers. The Mad Fiber’s unique hybrid construction involving an aluminum rim surrounded by carbon fiber negates any potential failures that can occur with poorly constructed full-carbon clinchers. However, their braking surface is still carbon fiber, and compared to the other wheels in our test, the Mad Fibers offered noticeably weaker stopping power. Our

Mad Fiber clincher wheels were the least grabby among our three contenders, but they performed well in all conditions, including long, steep and technical descents. We’d feel confident riding them anywhere, but they do require a bit of extra forethought and brake-lever grab to execute a quick stop. Although the Bontragers utilize a similar cork brake pad as the Mad Fibers, they offered significantly better braking power and modulation, which we attribute to the proprietary surface treatment on the brake track. The ENVEs are not the standout winner in the braking category, as they provide roughly the same stopping power as the Bontragers. But with slightly better modulation, particularly throughout longer and/or high-speed descents, the ENVEs proved to be the best of the bunch in braking.


DURABILITY

Among other ventures throughout hundreds of miles of testing, our ENVE wheels were ridden along the very same routes of the first five stages of the 2012 Tour of California. At no point during our testing did we experience any durability issues with them. It was the same story with the Mad Fibers, with absolutely zero durability problems arising throughout our tests. While we felt nothing but confidence in the Bontrager’s performance, particularly on descents, we did experience one circumstance of suspect build quality: after approximately 300 miles of riding, a small area of the front rim’s brake track started flaking, with a few tiny patches of surface resin having fallen off.

THE VERDICT

Visually, the Mad Fiber Clincher is one of the most striking wheels on the market, one that won’t ever be mistaken for any other wheel. The wheelset’s ride quality is just asunique, and the more we spent time on it, the more we enjoyed it. Unfortunately, that plush ride comes at the expense of stiffness, so the sprinters among us preferred the Bontragers as their go-to wheels. With the $1000 price difference to the ENVEs, the Aeolus 5 D3 clincher is in the running for the best all-around wheelset available for the money, a wonderful example of real-world aerodynamic capabilities in a clincher package. But at 50mm deep, and even with terrific crosswind handling, they may prove too deep for the average cyclist’s everyday use. So for those who prefer impeccable handling prowess in all conditions and who want clincher convenience with carbon performance, we recommend the ENVEs. Combine the contemporary design features, subtle graphics and great all around performance, and the Utah-made hoops are simply a notch above the others.

STATS:

BONTRAGER
Price: $2699.98
Weight: 1620 grams (without quick releases); 1757 grams (with quick releases)
Rim depth: 50mm
Rim width: 27mm
Spoke count: Front, 18; rear, 24
Spoke type: DT Aerolite
Spoke pattern: Radial (front); 2-cross (rear)
Notes: Available for both Shimano/SRAM and Campagnolo. Includes quick releases, pads, bags and valve extenders.
For more info: Bontrager

ENVE
Price: $3549 (DT180); $3045(DT240); $3203 (King R45); $1024 (rim only, front or rear)
Weight: 1466 grams (without quick releases); 1572 grams (with quick releases)
Rim depth: 35mm front, 45mm rear
Rim width: 26mm front, 24mm rear
Spoke count: Front, 20; rear, 24
Spoke type: DT Aerolite
Spoke pattern: Radial (front); 2-cross (rear)
Notes: Available for both Shimano/SRAM and Campagnolo. Includes quick releases, pads and valve extenders.
For more info: ENVE

MAD FIBER
Price: $2899 (stainless steel bearings); $3099 (ceramic)
Weight: 1301 grams (without quick releases); 1345 grams (with quick releases)
Rim depth: 60mm front, 66mm rear
Rim width: 20mm
Spoke count: Front, 12; rear,18
Spoke type: Non-replaceable, carbon fiber
Spoke pattern: Custom star pattern
Notes: Available for both Shimano/SRAM and Campagnolo. Includes quick releases, pads, valve extenders and a wheel magnet.
For more info: Mad Fiber

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