Better crosswind stability, great aerodynamics, a magnetic rear hub and a silicon carbide brake track. These are the main characteristics of the new Zipp 303 NSW wheels, which come in at a claimed 1,425g for the $3,100 / £2,150 set. In related news, Zipp also now has disc-brake versions of its deeper-rim 404 and 808 aero wheels, plus a new carbon stem and seatpost.
Zipp 303 NSW
After rolling out the NSW technology with its ultra-deep 808 wheels then the 58mm 404s, Zipp now has NSW technology in its popular 45mm wheel depth.
For those familiar with the 303 family, the 303 NSW is similar — an aero wheel with a broad, 17.25mm internal width that swells to 28.50mm at the rims widest external point. Sapim CX-Ray spokes are laced, 18 front and 24 rear, to what Zipp calls “the most aerodynamically efficient rim design on the market”.
What is new with NSW is the external rim texture that Zipp says lowers side force on the wheels by causing aerodynamic shearing faster than a smooth rim of the same shape. Faster shearing means that instead of pressure building up and then all of a sudden shearing — which you feel as a jerk to the side — pressure is released multiple time a second. (50 times a second if you are going 20mph, Zipp says.)
“While playing with different dimple patterns, we stumbled upon something we didn’t initially understand,” Zipp's director of advanced development Michael Hall told BikeRadar. “This particular configuration has low drag, but at a certain yaw angle the side force just drops off the map.”
Drag refers to the aerodynamic properties of an object moving through the wind. Lower is better. Side force is what you feel pushing on the side of deep wheels when riding in strong crosswinds. Again, lower is better here.
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“At 17 degrees of yaw, this design has low drag and even lower side force,” Hall said. “That high yaw angle is really where you’d have the biggest affect on handling, because there is that amount of pressure.”
Compared with the standard Zipp Firecrest aero wheels, Hall said the side forces on the NSW “are pretty much matched gram for gram at lower yaw angles. NSW maintains lower drag values throughout the yaw range. But starting about 17%, NSW side force plummets and still maintains a lower CDA [drag] than the Firecrest design.”
Zipp says the NSW wheels are 34% more stable in crosswinds, based on the average of a full yaw sweep of measurements.
Other notable technology in the NSW wheels include the Showstopper sculpted brake track that Zipp claims has equal brake force compared to industry-leading alloy rims and more stopping power in wet than any carbon wheel. Big claims, indeed.
inally, the NSW wheels have the new 225g Cognition rear hub, which features six magnets that drive 36 points of engagement with two parallel rings. The Cognition hub is compatible with SRAM’s XDR driver body, which can accept a 10-42t cassette.
For now, the NSW wheels are clincher only.
Zipp 303 NSW
1,425g (640g front, 785g rear)
$3,100 / £2,150
Available in May
Zipp 404 Firecrest and 808 Firecrest
After rolling out disc brakes first on the Zipp 303 Firecrest, the Indiana brand now has rotors bolted on the tall 404 and the ultra-tall 808 wheels, too.
Zipp claims the 82mm 808 is the fastest road wheelset available.
Both wheelsets use 24 spokes front and rear, and the 77/177D hubset, which is thru-axle compatible. With the switch of some end caps, the wheels can be used with:
Quick releases front and rear
100x12 or 100x15mm front thru-axles
135x12 or 142x12mm rear thru-axles
The rear hub is also compatible with the XDR driver body that works with SRAM’s 10-42t cassette intended for use with 1x systems.
Zipp 404 Firecrest Disc Brake
1,715g clincher (800g front, 915g rear)
$2,400 / £1,920
1,545g tubular (710g front, 835g rear)
$2,300 / £1,840
Available in May
Zipp 808 Firecrest Disc Brake
1,975g clincher (950g front, 1,025g rear)
$2,700 / £2,160
1,760g tubular (820g front, 940g rear)
$2,600 / £2,080
Available in May
Zipp SL Speed Stem and SL Speed Seatpost
This spring Zipp also has new carbon components dubbed SL Speed.
“We wanted to beat competitors on weight, but we had to maintain durability,” said Zipp product manager Nathan Schickel. “The SL Speed stem has the highest stiffness to weight of any stem. It’s not the stiffest, that’s the SL Sprint, which is a little heavier.”
The SL Speed Stem weighs a claimed 123g for a 100mm length, and comes in 10mm increments from 70-120mm.
The unidirectional carbon stem uses Zipp’s standard Torx T25 bolts, but in titanium for weight savings.
Zipp SL Speed Stem
31.88 clamp
50mm clamp width
$265 / £110
Available in May
The SL Speed Seatpost will come in 0 and 20mm offsets, in 27.2 and 31.8mm diameters. It is compatible with round and square rails, and has a 300lb weight limit.
Schickel said that while it’s not designed for mountain biking, Zipp tested it as such because more riders are expanding their definition of road riding to include some rougher paths.
Zipp also has a Di2 internal battery mount for the SL Speed Seatpost in both diameters.
