Fifty millimeters of carbon rim depth occupies a deliberate middle ground in Zipp's wheel lineup, and the 404 S plants itself there with a focus on versatility rather than outright aero extremes. Where the 404 Firecrest runs 58mm deep with Zipp's ABLC dimple treatment, the 404 S from Zipp takes a shallower approach that trades a fraction of flat-road speed for reduced crosswind sensitivity and a lighter overall feel. The hookless Tubeless Straight Side rim construction narrows the tire-to-rim junction for a smoother aerodynamic transition, and the tubeless-only compatibility means clincher tires with inner tubes are not an option here.

The 23mm internal rim width supports tire widths from 28mm through 39mm, which positions the 404 S as a road wheel that can comfortably stretch into mixed-surface territory. Running wider tires at lower pressures on a hookless rim reduces rolling resistance on imperfect pavement and improves grip through corners — a measurable advantage that compounds over the duration of a long road race, gran fondo, or gravel-adjacent route. The symmetrical rim profile distributes spoke tension evenly, and the UD carbon fiber finish with adhesive decals keeps the aesthetic clean without adding the weight of a painted surface.

Zipp builds the 404 S front wheel with a 20-spoke count in a 2-cross lacing pattern using Sapim CX-Sprint spokes and aluminum nipples with Sapim Secure-Loc anti-rotation features. The lower spoke count compared to a 24-spoke rear build reduces aerodynamic drag from the spokes themselves — a meaningful consideration at the speeds where aero gains matter most. This is a front-specific wheel, so there is no driver body or freehub mechanism; the 76D hub spins on stainless steel cartridge bearings with aluminum axle material, and the 12x100mm thru-axle spacing fits the standard disc brake road fork configuration.... Read More