Zipp's latest evolution of their 404 wheels is undoubtedly their most predictable, comfortable and versatile high-velocity set yet, making them true aero all-rounders.
The Firecrest tag comes from Zipp’s uniquely blunt-nosed, fat-bodied rim profile. This is designed to manage both leading and trailing edge airflow to shift the aerodynamic centre of the wheel back towards the hub, rather than near the front edge like simpler wheels.
This is immediately obvious too, with none of the stubborn ‘tramlining’ effect of typical 60mm wheels and it doesn’t snatch the steering in gusting winds either. You’ll still get shoved sideways by squalls, but it’s very predictable and controllable.
While aerodynamic claims are hard to quantify categorically outside the wind tunnel, heart-rate versus speed comparisons show noticeable average speed gains and they hold speed at much broader wind angles than conventional wheels.
The lightweight rims and 1,286g overall weight mean they’re no slouch when sprinting or climbing either, with no rim rub at maximum power. The fatter profile and wider tyre base also makes the 404s surprisingly comfortable, so not only do they increase speed, they also reduce fatigue.
Increased compliance means you can properly chuck them into corners and they're phenomenal descending wheels. Braking is far better than most carbon hoops too, if you opt for Zipp’s Platinum pads. Not only are the tubs 279g lighter than the carbon clinchers but they’re also £400 cheaper, making it well worth learning to live with glue-on tyres.
This article was originally published in Triathlon Plus magazine.