The Zipp 404 has been one of the most popular and successful aero road wheels ever produced. Zipp introduced them 3 decades ago and updates them regularly, improving them with each iteration.
Today, Zipp announced a new release of the 404 Firecrest and man, oh man, there is a huge change! The basic structure of the new 404 Firecrest shifts how wheels address efficiency. And if it bears out, that efficiency will translate to more speed.
The new Zipp 404 Firecrest Tubeless Disc Brake wheels feature a 23mm internal width and a hookless bead. This modification will facilitate the use of wider tubeless tires at reduced air pressure. And the larger volume tire and lower pressure should reduce vibrational losses of power and efficiency.
The bottom line: Real-world, outdoor testing commissioned by Zipp revealed a 4-watt saving for a 187-pound rider traveling 40 kph on the new wheels with 25mm tires compared to the previous 404 Firecrest.

‘Total System Efficiency’
Instead of narrowly focusing on aerodynamics, Zipp applied what it calls Total System Efficiency (TSE) on its newest release. This philosophy encompasses multiple factors that affect performance: wind resistance, gravity, rolling resistance, and vibration losses.
Zipp addresses vibrational loss with the 404 Firecrest’s broader internal width and hookless bead. Specifically, these wheels’ ability to run higher volume tires at a much lower pressure realize gains in efficiency. This might come as news for riders like myself who believed that weight and aerodynamics ruled all.
And for seasoned road riders like myself, Zipp’s recommended tire pressures for the new 404 Firecrest are almost unbelievably low. For my training weight of 175 pounds, with 25c tires, Zipp’s online tire pressure calculator specifies 70.8 psi in the rear and 66.6 psi in the front!
Zipp advises confirming the compatibility of tires with the manufacturer and provides a list here.
Zipp’s studies and engineering process determined that reducing vibrational losses significantly improved overall performance for an all-around road racing and training wheel. And it had to be significant enough to justify altering one of the brand’s best-selling and most respected wheel lines ever.

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