Aero bike wheels are excellent at cutting down on aerodynamic drag in a straight line, but they can be tricky to handle in a crosswind. Zipp's new 454 NSW Carbon Clincher has been designed with efficiency in mind, using shapes from nature for less aerodynamic drag and buffeting than regular aero wheels.
In a strong breeze, riders using traditional aero wheels are forced to make constant corrections just to stay in a straight line. Not only is it annoying, it's inefficient. With this in mind, the team at Zipp developed the Carbon Clincher's unique Sawtooth shape, which ranges between 53 and 58 mm (2 and 2.3 in) deep. The jagged design works with a new set of fin-shaped nodes fitted along the inner diameter of the rim called HyperFoils, which Zipp says mimic the detail on the front edge of a whale's pectoral fin.
Both of these elements have been designed to work in tandem with one final puzzle piece: sets of hexagonal dimples (or HexFin ABLC Dimples) on the side of the rim. According to Zipp, these dimples increase the frequency of vortex shedding, which cuts down on annoying buffeting in crosswinds.
Each individual rim is hand-assembled at the Zipp factory in Indianapolis, and takes around 12 hours to put together and test. Coupled with the 252 hours the company says it spent in the wind tunnel before settling on the final shape, it goes to show nailing down aerodynamics is a slow and laborious process.
As you might imagine, it's not cheap to spend so long developing and assembling small batches of wheels. A set of front and rear 454 NSW Carbon Clinchers will cost you an eye-watering US$4,000.