The Ideal Balance of Weight, Aerodynamics, and Aesthetics for Road Racing

The Zipp 404 S Rear Wheel is a 700c carbon road wheel designed for road racers, criterium specialists, and high-performance pavement riders who want meaningful aerodynamic performance without sacrificing crosswind stability. At 50mm rim depth, the 404 S sits in the mid-depth aero category - aerodynamically effective on flat and rolling terrain where depth translates to drag reduction, while remaining stable enough in crosswind conditions that it does not compromise the rider's control or confidence on exposed courses.

The rear wheel uses an XDR freehub body - compatible with SRAM's XDR cassette standard used on SRAM Red, Force, Rival, and other XDR-equipped road groupsets. XDR is not compatible with standard Shimano HG cassette bodies. Confirm your drivetrain uses XDR cassettes before purchase. This listing is for the rear wheel only with 12mm thru-axle at 142mm rear spacing. The matching 404 S front wheel is available separately. No skewers are included. A disc rotor is not included - the hub uses a centerlock interface, not 6-bolt. The wheel carries a Lifetime Warranty from Zipp.

50mm Depth, 23mm Internal Width, and Total System Speed

The 404 S rim uses Zipp's TSS (Total System Speed) approach - considering the wheel's aerodynamic performance as part of a complete tyre-wheel system rather than evaluating the rim profile in isolation. The 23mm internal width sits within the rim's rated range of 22 to 27.9mm, supporting road tyre widths from 28mm to 40mm at lower pressures than a narrow rim would allow for equivalent performance. Running wider road tyres at lower pressures reduces rolling resistance on real road surfaces where imperfections cause energy loss - a meaningful performance factor on the varied pavement conditions of road racing.

The 50mm depth provides the aerodynamic benefit of a deep-section wheel while remaining manageable in crosswinds - the profile shallow enough relative to deeper aero options to maintain stability without requiring the rider to actively compensate for crosswind forces that deeper rims create. For criterium racing where constant direction changes, tight corners, and varied wind exposure occur throughout the race, the 50mm depth strikes a more practical balance than a 60mm or 70mm alternative.

ZR700 Hub, Sapim CX-Sprint Spokes, and 20-Hole Lacing

The rear wheel uses Zipp's ZR700 hubset - a purpose-built hub for the 404 S that uses a centerlock disc interface and XDR freehub body. The hub is laced 20 holes in a 2-cross configuration using Sapim CX-Sprint spokes - a different spoke specification from the CX-Ray used in the 303 XPLR S. CX-Sprint spokes are Sapim's aero road spoke optimised for the load characteristics and spoke angles of a 20-hole low-spoke-count wheel build, providing the structural integrity needed for a 20-hole rear wheel while maintaining aerodynamic profile.

The 20-hole lacing provides a very low spoke count for aerodynamic benefit - fewer spokes means less total spoke surface area disrupting airflow around the wheel. The 2-cross lacing pattern balances spoke tension and lateral stiffness for a rear wheel expected to handle the torque loads of hard sprinting and the cornering forces of criterium racing.

The wheel is Tubeless Ready - accepting tubeless tyre mounting for lower pressures, improved puncture resilience, and the reduced rolling resistance of a sealant setup. The rim profile accepts tyres from 28mm to 40mm in width, providing meaningful flexibility for riders who use different tyre widths for different race courses.

FAQs

What freehub body does the Zipp 404 S rear wheel use?

This version uses a SRAM XDR freehub body - compatible with SRAM XDR cassettes used on Red, Force, Rival, and other SRAM XDR road groupsets. XDR is not compatible with standard Shimano HG cassette bodies. Confirm your drivetrain uses XDR before purchase.

Is this a front or rear wheel?

This listing is for the rear wheel only with 12mm thru-axle at 142mm rear spacing and centerlock disc interface. The matching 404 S front wheel is available separately.

Why does 50mm depth balance aerodynamics and crosswind stability better than deeper alternatives?

At 50mm depth the 404 S provides meaningful aerodynamic drag reduction without the crosswind sensitivity that 60mm or 70mm rims impose. For criterium racing and varied road conditions where crosswind exposure is unpredictable and constant direction changes are required, the 50mm depth maintains rider control and confidence that deeper sections can compromise.

What tyre widths is the 404 S compatible with?

The rim supports tyre widths from 28mm to 40mm with an internal width of 23mm, rated for the 22 to 27.9mm internal width range. This covers the full range of road racing and performance road tyres commonly used at this rim depth.

What warranty does the Zipp 404 S carry?

The wheel carries a Lifetime Warranty from Zipp.