Zipp extends Firecrest rim profile to 404 and 808 wheels
New rim profile doesn't look like it should be faster but Zipp claims Firecrest actually improves aerodynamics under less than ideal conditions
Zipp launched its new Firecrest rim on the all-new, all-carbon 404 clincher rim back in May. Last week at Eurobike, the surprisingly fat profile was rolled out on the tubular version of the 58mm deep rim, as well.
The deep 808 wheels in both tubular and clincher versions get the new Firecrest treatment too.
According to Zipp Technical Director Josh Poertner, "Firecrest refocused our thinking about aerodynamics from the front to the back of the wheel, and it also gave us a chance to explore how even the smallest adjustments in the curve of the rim profile can improve every other aspect of the wheel's performance."
Whereas earlier Zipp rims had their widest point near to the tyre with an accentuated taper and sharp edge, the Firecrest profile moves the bulge close to the spokes, with a distinctly snub edge. The bulge is actually wider than the rim bead, increasing from 25.5 to 27.5mm.
Zipp claim that at a 10-degree wind angle, the performance improvements from Firecrest are substantial: 9 seconds over 40km for the 404 Tubular, and 15 seconds for the 808 Tubular that is now faster than any 90mm rim and even some disc wheels. At higher wind angles, the benefits are claimed to be even more dramatic.
In crosswinds, according to Zipp, Firecrest rims provide markedly more stable handling than other rims of equal or even shallower depth. The wide rim profile also increases stiffness for sprinting and cornering while adding comfort and durability on rough surfaces.
Despite the upgraded aerodynamics, weights for Firecrest-based Zipp wheels remain at the lighter end of the scale: 1,278 grams for the 404 Tubular, 1,557 grams for the 404 Carbon Clincher, 1,519 grams for the 808 Tubular and 1,759 grams for the 808 Carbon Clincher.
Now all the 404 and 808 rims will employ Zipp's own heat-resistant resin to improve braking performance and handling by preventing the spikes in rim temperature and tyre pressure that can occur under heavy, continuous braking. Furthermore, they pass CEN safety standards without any limitations on rider weight or brake pads - a certification that no other carbon wheelsets have achieved, according to Zipp.
No UK pricing yet. With the 404 Carbon Clincher already available, the new models start with the 808 Carbon Clincher in October.