For races against the clock, or no-draft long distance triathlon events, the fastest wheel in nearly all conditions is a rear aero disc. Paired with a deep section spoked front wheel, the potential speed with an aero bike, equipment and efficient body position few set-ups have the potential to be faster than one equipped with Roval's 321 Disc Wheel. With a stunning design, beautiful construction, and all the crucial features that deliver speed and efficiency, the revolutionary 321 is purpose-built to give you an edge in the race against time. In real-world conditions, it is the most aerodynamically efficient wheel ever made; featuring a unique asymmetric, lenticular construction that cheats wind and conserves precious watts. At 1000 grams, it’s also the lightest production aero disc wheel around. While Roval does offer this in a disc brake version, this item is the rim brake, quick release axle version for 130mm road bike rear dropout spacing.

Leveraging powerful Computational Fluid Dynamics (CFD) was key to the aerodynamic optimization of the 321. CFD enabled Roval's engineers to very closely estimate the drag that the wheel would generate. They then utilized that data to revise the shape of the 321 in the computer until it was close to perfect. Working from the data gleaned from the CFD process, the technicians created 3D printed models of the 321 and tested them in the wind tunnel. Working the physical model at various yaw angles, with a real tire mounted, installed in a real bike, the team generated drag data that was used to further optimize the 321 design. Long before seeing any pavement, the 321’s shape was honed through these successive iterations of prototypes. Each one of those prototypes was fed into Specialized's "Win Tunnel", for tests in all possible conditions, then sent back for revision. The final production wheel represents thousands of hours spent testing in this exacting arena and the results speak for themselves, including Ironman World Records, UCI World Championship titles, and Grand Tour stage wins.

The tubeless ready, 19mm inner width of the 321 rim is tailored to fit modern, wider tires. The wheel itself is the result of rigorous testing in our wind tunnel to ensure that it delivers maximum laminar flow and aerodynamic efficiency with those same wider tires. Through innovative geometry and layup Roval created a 1000 gram wheel; and no production disc is lighter. The non-drive side of the 321 is the most aerodynamically efficient shape possible; it bows in a lenticular form from the hub to the rim. The engineers would have done that with the drive side as well, but they had to make room for the cassette and chain, so that side is flatter, but still very slippery.

On an aero disc rear wheel, precision construction and attachment to the hub is paramount. The hub itself must be perfectly machined, so Roval creates their own 321 aero disc hub for rim braking, but taps into two of the industry's top manufacturers to deliver response, pure rolling speed, and easy serviceability. CeramicSpeed bearings are the lowest friction, most energy efficient bearings money can buy. When seeking out hundredths of seconds and applying every available watt of energy to maximize speed, friction reduction and attention to detail matter most. Keeping with this theme of performance above all else, the 321 hubs are finished with precision DT Swiss 240 internals and freehub engagement. Proven World Tour performance and reliability gets you the finish faster, every time.