We all know that "aero" and "Zipp" are virtually synonyms, and the company's latest scalps include Kona and a World's TT, both of which were won on the 808 NSW. With the 404 NSW Carbon Clincher Road Wheel, Zipp brings the deeper model's aerodynamic features and a brake track that's "no longer as good as aluminum, it is better" to a more all-purpose, 58mm depth. This represents an upgrade to the Firestrike 404, which was itself wider, stronger, and more aerodynamic than the standard Firecrest.
It's important to stress the fact that the 404 NSW is, essentially, an upgrade to a recent — and very successful — upgrade. To be frank, our experiences on the 404 Firestrike have been so good that we're surprised Zipp has already seen fit to completely overhaul it, but that's exactly what the NSW model is: an overhaul of an already revolutionary design. As alluded to above, the rim's braking and aerodynamics have both seen improvements with no sacrifice to durability, and the NSW 404's refined carbon lay-up earns the set a claimed weight that's 65g lighter than the Firestrike equivalent and 135g lighter than the Firecrest. But believe it or not, it's not the rim that we're most excited about; it's the Cognition hub the rim is laced to.
We admit that we haven't always associated Zipp with hub innovation — a fact attributable primarily to the above mentioned aerodynamic rim sorcery — but the NSW's Cognition rear hub may be the most exciting technology in factory wheels that we've seen since Zipp first introduced its bulging sidewalls. The hub is centered on Zipp's Axial Clutch mechanism, which features two Metal Injection Molding (MIM) ratcheting rings — one mated to the freehub body and one mated to the hub body. The two rings are machined like a ratchet, so they ramp off of each other while freewheeling but engage each other during pedal input.
Compared to a standard pawl design, which actually resembles a drum brake, the Axial Clutch's MIM rings engage laterally to reduce friction while freewheeling, so coasting doesn't negate watts already spent. We're familiar with this model, as we've seen similar mechanisms on the designer hubs featured in top-end custom builds for years now, but Zipp is the first to replace the usual tensioning agent, steel springs, with magnets. This substitution further reduces friction between the ratcheting rings, making for what may be the smoothest freewheel on any mass-produced hub set. It's a design that we suspect will eventually be the norm, but — once again — Zipp is leading the charge.
Shiny new hubs aside, we now return to the subject you probably expected to be the headline for a new Zipp wheel. The brand's signature Aerodynamic Boundary Layer Control (ABLC) dimpling returns with a new designation. It's called SawTooth Technology, and it consists of ABLC dimples applied in a single pattern repeated in 12 discrete swathes (or "nodes") across the rim's surface, looking much like the strokes of a paint brush. Zipp's description of SawTooth's effect is a bit, how shall we say, erudite, with the company claiming a 34% reduction in side wind forces compared to the previous Firestrike 404 by "reducing the laminar bubble effect on the aerodynamically shielded side of the rim's profile." Translated into saddle speak, that means while rolling at 20mph and above, the rim's dimpling is designed to dispel the negative, drag-inducing force on the rim's non-wind side.
SawTooth's premise stems from 42 computational fluid dynamics studies and testing that spilled out of the wind tunnel onto — gasp! — actual roads. In actual wind. You know, the conditions that we actual cyclists face every time we throw a leg over the top tube either side of trainer season. To help understand how SawTooth works, consider an aerodynamic NACA shape in the pristine wind tunnel conditions of zero-degrees yaw. When air resistance is perfectly head-on, drag only exists in a parallel plane with an object, so a teardrop NACA cross section reduces drag to its absolute minimum by reducing the wake. Turn the yaw angle upwards of 15 or 20 degrees, though, and a true NACA shape begins to experience drag from the side opposite cross wind pressure as well. This lateral drag is Zipp's "laminar bubble," and it's the phenomenon responsible for the violent instability that leaves us wrestling with our bikes on gusty days.
Though Zipp was one of the shape's early adopters, the industry is now replete with rounded, bullet-shaped rim designs that aim to lessen destabilizing drag from cross wind forces; however, if Zipp's numbers are any indication, the SawTooth nodes take that reduction to a whole new level by better controlling cross winds as they detach from the rim's opposite face. While deep rims will always be more vulnerable to lateral forces than shallow box clinchers, the Firecrest DSW's rim shape and SawTooth Technology contribute to a ride that requires less correction in windy conditions, and the corrections themselves are more subtle and intuitive than with yesterday's NACA profiles.
The rims are finished with Zipp's ImPress graphical treatment, which involves directly printing the aesthetic embellishments onto the rim rather than applying decals. This leaves the SawTooth nodes of ABLC dimpling uninterrupted and unimpeded. Finally, it's only appropriate that we end the way every good ride does: with the brakes. The rims are equipped with an updated version of Zipp's Showstopper brake tracks. Showstopper enjoyed an impressive debut on the Firestrike 404, but it's already been improved for the NSW model. It's still imbued with the same silicon carbide particles, but the direction-specific grooves have increased in number and feature an altered depth. The original Showstopper netted some pretty impressive stopping across all conditions; while we haven't tested this new brake track, Zipp assures us that it's even better. The upshot is you can hold speed longer while approaching a corner, braking later and gaining tiny increments of time with each bend or switchback.
- Carbon fiber rim
- 58mm rim depth, 17.25mm internal rim width
- Zipp Cognition hubs
- Aerodynamic Boundary Layer Control (ABLC) dimpling
- Showstopper brake track
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Reviews & Community
The new Zipp 404
- Familiarity: I've put it through the wringer
I raced with the carbon/alloy Zipp 60s (the older generation 404) and was well pleased with them. But the 60s were narrow rims intended for 21mm tires. Nobody sells tires in that size anymore, and running tires too wide not only negated the aero benefits but hurt cornering as well. So I bit the bullet and figured I'd go with the best Zipp had to offer.
I only have the front wheel so far, but it's pretty amazing. It's nice and light. A 23mm tire, which is what the rim is designed for (for max aero benefit), fits flush with the brake track. I run the front tire at 90psi and oh wow it's so buttery smooth. On a long ride I have no fatigue from vibration through the front wheel--that alone is worth the price for me. The brakes work very nicely and I've ridden them in rain and not noticed any difference in stopping. The marginal aero gain over the Zipp 60 is not within the realm of detection, at least for me, but they do seem to handle quite well in crosswinds and if I can save 7 watts in a race over the Zipp 60s that's still huge. The wheel also looks the business. I also love the fact that I can get tires on and off without needing tire levers.
If there's one annoyance I have so far with the wheel is when descending fast sometimes I can feel the wheel get slightly pushed by wind. While I've never felt like I was ever going to lose control of the bike (and the effect was momentary), it was sudden and still disconcerting. But maybe I'm getting used to it--I'm getting a bit braver on the downhills, so this may just be me.
Better than the Firecrest 404? I can't say--what drew me to these over the Firecrests were (1) the wider rims and (2) the braking. They're definitely better than the Zipp 60s, though.
Zip 404 NSW wheels
- Familiarity: I've used it several times
They are a fantastic set of wheels! I've own a few sets of Zipps 404 Firecrest wheels and the new NSW wheel set is in many ways an improvement starting with the hubs to the new braking surface giving you the stopping power you need when decending.