We all remember when carbon fiber was regarded as the Faberge egg of the northern classics. That all changed in 2010, and Spartacus swept the cobbled monuments on the best form we've ever seen in spring and a pair of 303s. Since then, it's been all carbon, all the time, and with the tubeless 303 NSW Carbon Disc Brake Road Wheel, Zipp's made the 303 line even more capable of tackling Cancellara's preferred race terrain. Cobblestones, limestone gravel, and the occasional patch of tarmac—all comers are welcome.
Despite the advancements to rim, which is the element of the wheel that Zipp's tag line of "Speed Weaponry" is typically associated with, we're going to start here with the Cognition hub. Blasphemy, we know, but the Cognition makes a strong case for itself. We'd even go so far to suggest that the NSW's Cognition rear hub may be the most exciting innovation we've seen in factory wheels since Zipp first introduced its bulging sidewalls. The hub owes its sex appeal to Zipp's Axial Clutch freewheel design, which features two Metal Injection Molding (MIM) ratcheting rings—one mated to the freehub body and one mated to the hub body. The two rings are machined like a ratchet, so they ramp off of each other while freewheeling but engage each other during pedal input.
Compared to a standard pawl design, which actually resembles a drum brake and engages from the inside out, the Axial Clutch's MIM rings engage laterally to reduce friction, so the engagement mechanism itself doesn't tax as many watts from your efforts. We're familiar with this model, as we've seen similar mechanisms on the designer hubs featured in top-end custom builds for years now, but Zipp is the first to replace the usual tensioning agent, steel springs, with magnets. This substitution further reduces friction between the ratcheting rings, making for what may be the smoothest freewheel on any mass-produced wheel. It also carries the added bonus of sounding really, really cool. The Cognition's Axial Clutch system emits an aggressive, ominous growl compared to the typical Zzzzzz of pawls. It's a design that we suspect will eventually be the norm, but—once again—Zipp is leading the charge.
Shiny new hubs aside, we'll get back to the subject you probably (and rightfully) expected to be the headline for a new Zipp wheel: the rim. The brand's signature Aerodynamic Boundary Layer Control (ABLC) dimpling returns with a new designation. It's called SawTooth Technology, and it consists of ABLC dimples applied in a single pattern repeated in 12 discrete swathes (or "nodes") across the rim's surface, looking much like the strokes of a paint brush. Zipp's description of SawTooth's effect is a bit erudite, with the company claiming a 34% reduction in side wind forces compared to the previous ABLC pattern. It achieves these gains by "reducing the laminar bubble effect on the aerodynamically shielded side of the rim's profile." Translated into saddle speak, that means while rolling at 20mph and above, the rim's dimpling is designed to dispel the negative, drag-inducing force on the rim's non-wind side.
SawTooth's premise stems from 42 computational fluid dynamics studies and testing that spilled out of the wind tunnel onto—gasp!—actual roads. In actual wind. You know, the conditions that we actual cyclists face every time we throw a leg over the top tube either side of trainer season. To help understand how SawTooth works, consider an aerodynamic NACA shape in the pristine wind tunnel conditions of zero-degrees yaw. When air resistance is perfectly head-on, drag only exists in a parallel plane with an object, so a teardrop NACA cross section reduces drag to its absolute minimum by reducing the wake. Turn the yaw angle upwards of 15 or 20 degrees, though, and a true NACA shape begins to experience drag from the side opposite cross wind pressure as well. This lateral drag is Zipp's "laminar bubble," and it's the phenomenon responsible for the violent instability that leaves us wrestling with our bikes on gusty days.
Though Zipp was one of the shape's early adopters, the industry is now replete with rounded, bullet-shaped rim designs that aim to lessen destabilizing drag from cross wind forces; however, if Zipp's numbers are any indication, the SawTooth nodes take that reduction to a whole new level by better controlling cross winds as they detach from the rim's opposite face. While deep rims will always be more vulnerable to lateral forces than shallow box clinchers, the NSW's rim shape and SawTooth Technology contribute to a ride that requires less correction in windy conditions, and the corrections themselves are more subtle and intuitive than with yesterday's NACA profiles.
The improvements in aerodynamics even extend to the wheel's graphics. The rims are finished with Zipp's ImPress graphical treatment, which involves directly printing the aesthetic embellishments onto the rim rather than applying decals. This leaves the SawTooth nodes of ABLC dimpling uninterrupted and unimpeded all the way to the tire bed—keep in mind that there's no brake track on the rim to hem them in.
Speaking of which, it's only appropriate that we end the way every good ride does: with the brakes. Rather than the impressive braking of Zipp's Showstopper brake tracks, which feature on other NSW models, these wheels are only interested in rotors. Disc brakes do something that rim-brake carbon can only dream of: surpass alloy in terms of modulation, responsiveness, and overall stopping power. Knowing you can depend on your brakes means you can carry more speed into corners, brake later, and not worry about locking your wheels up when an unexpected obstacle—an off-leash dog where a trailhead connects to a canyon road, the inevitable sudden motorist, rubble sloughed off of a canyon wall—materializes.
Maybe it started out as a road wheel 10+ years ago, but—as we stated above—the 303 is undeniably capable of riding all manner of surfaces. Toward that end, every NSW Disc Brake wheel ships with thru-axle conversion end caps for 12 or 15x100mm up front and 12x142mm in the back. The wheels also include standard quick-releases, so regardless of your gravel, 'cross, or road axle standards, you should be covered.
- The wheels that changed the classics get updated for the better
- Mid-depth rim blends speed and handling for any discipline
- Disc brakes add confidence to braking in all conditions
- Tubeless construction increases comfort and supple feel
- Better flat prevention and easier recovery for when you do puncture
- Improved carbon layup increases durability while shedding grams
- Includes quick-release skewers and fork thru-axle end caps
- Zipp once again pushes carbon wheel tech into a brave new world