Zipp Speed Weaponry recently revealed their Firecrest line. What is Firecrest? We’re glad you asked.
Zipp’s proprietary Firecrest rim rewrote the fundamentals of wheel making, resulting in improved aerodynamics, ride quality, wheel strength and stability in even the strongest of crosswinds. As a result, the entire Firecrest family of wheels makes a bigger difference in more ways than ever.
Firecrest technology, discovered as Zipp developed their Carbon Clinchers, refocused their thinking to concentrate not only on the front half of the wheel, but also the back half. Previous rim shapes were designed to smooth airflow coming off the tire, and tapered inward from the widest point of a toroidal bulge. But Firecrest rims have a less pronounced bulge and maintain a near-constant width almost all the way to the spoke bed. Without giving up the proven benefits of the toroidal shape, Firecrest is the first aero profile that effectively controls airflow around the back half of the wheel.
The performance benefits are substantial. At 1,375 grams, the 202 Firecrest Carbon Clincher (32mm rim depth) is the lightest in Zipp’s Carbon Clincher lineup and is a plucky all-around performer that floats up mountains and provides superior aerodynamics on the flats and descents. The 303 Firecrest (45mm rim depth) has become the go-to wheel for the Omega Pharma – Quick-Step Cycling Team at the Spring Classics and the wheel of choice for many of the women on Team Exergy TWENTY12. With Firecrest, the 404 Firecrest Tubular (58mm rim depth) matches the aero performance of the pre-Firecrest 808 (82mm depth). And what of the 808 Firecrest? Australian Pete Jacobs provided Zipp with the answer, blasting the 112 mile cycling leg at Kona a pair of 808 Firecrest wheels to capture the 2012 Ironman World Championship. “The crosswinds were never blowing me across the road. I always felt in control,” Jacobs said. “During the race I was thinking, “Wow, these 808s feel great.”
Zipp used Computational Fluid Dynamics (CFD) post-processing capabilities to maximize aerodynamics and minimize wind-induced steering torque, resulting in a 202 Firecrest Carbon Clincher (right) that is faster and better handling than a classic box-section road wheel (left). The Firecrest rim shape improves stability by moving the wheel’s center of pressure (represented in red/white) aft and downward to sit almost directly over the steering axis, where wind-induced steering torque has a minimal effect. CFD analysis also demonstrates how Zipp’s proprietary Firecrest rim shape results in significantly less wind drag — 131 grams for the 202 Firecrest, compared with 324 grams for the classic road wheel. Such use of CFD software throughout the development of the Firecrest line helped Zipp create better prototypes to take to the wind tunnel, resulting in the world’s most aerodynamic and stable wheels.
During the design process for Firecrest, Zipp realized that the advanced mathematics and massive computing power that helped them create a faster wheel could also help reduce the impact of crosswinds on handling. Using computational fluid dynamics (CFD) software, Zipp discovered subtle variations in rim shape that improve stability without increasing aerodynamic drag. By moving the center of pressure – the focal point of side forces on the rim – to its optimal location near the steering axis, Firecrest offers stable, predictable handling at every wind angle. With the 202 Firecrest Carbon Clincher, Zipp achieved a near neutral steering torque. In real-world conditions, Firecrest rims are markedly more stable than other rims of equal or even shallower depth.
As Zipp discovered when developing the Zipp 303 to thrive under unforgiving conditions at the Spring Classics, a wider rim increases lateral stiffness for sprinting and cornering yet offers greater vertical compliance for more control, comfort, and durability on rough surfaces. The same holds true for Firecrest rims. The 303 Firecrest is a proven performer on the open road, cobblestones or rough cyclocross courses. In both tubular and Carbon Clincher versions, the wider design places more rubber on the road while cornering without adding rolling resistance. The new 202 Firecrest Carbon Clincher uses a new resin system that builds on Firecrest’s foundation of strength.