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After years of focusing on reducing aerodynamic drag with its wheels, Zipp is now overhauling the top end of its line-up with wider internal widths with the aim of reducing rolling resistance, too. The goal is still the same: go fast. The new 454 NSW and 404 Firecrest wheels launched today are now wider internally, lighter, and, according to Zipp, faster than their predecessors.
Zipp’s new acronym, TSE, for ‘Total System Efficiency’ started with the revamped 303 Firecrest wheel.
“We know there are four barriers to speed,” said Zipp’s Michael Zellmann. “Wind resistance, gravity, rolling resistance, and vibration. With TSE we are considering the whole package and not just aerodynamic efficiency.”
Much of the claimed gains in speed come from lowered rolling resistance due to a wider tire configuration.
404 Firecrest — $1,900
An evolution of the original Zipp aero wheel from the 1990s, the 404 Firecrest Tubeless Disc Brake wheelset dropped 420g from its last iteration and plumped up internally to 23mm. The net result made for a faster wheel, Zipp says, when you look at rolling resistance improvements. Zipp tested the new and old wheels with a bike and rider weighing 187lbs. Using the same model 25mm tires and the same air pressure, the new wheels required 286 watts to maintain 40kph, whereas the old models required 290w, the company claimed.
Zipp admitted that the aerodynamic efficiency actually decreased slightly — by a fraction of a watt — but the improvements in rolling resistance clearly made the change worthwhile.
Optimized for 25mm tubeless tires, the 404 Firecrest with its 58mm rims weighs a claimed 1,450g.
454 NSW Tubeless — $4,000
Similar to the 404, the new 454 NSW Tubeless made big improvements in rolling resistance, to the tune of a 10w savings at 40kph.
The Sawtooth rim undulates between 53mm and 58mm tall. Total wheelset weight is a claimed 1,463g, a whopping 420g improvement from its predecessor.
The 454 NSW also gets a new hub. The Cognition DB V2 now uses a wave spring instead of magnets to engage the ratchet when pedaling. When coasting, the two ratchet parts separate and there is no friction between the two, Zipp claims. There are also now 54 points of engagement instead of 36.
Zipp 858 NSW — $4,000
Zipp’s deepest wheelset also gets an overhaul with an 18mm internal rim width and the new Cognition DB V2 hubs with the Axial Clutch V2.
The rim height undulates from 77mm to 82mm.
Claimed weight is 1,773g for the set.
You should probably lower your pressure
Many wheel and tire companies — and pro teams — are continuing to study how to optimize tire size, shape, construction, and air pressure. One common theme in recent years is that higher pressure isn’t necessarily faster in real-world conditions, especially when bumps are involved.
“We can’t overstate this: tire pressure is critical,” Zellmann said. “We know people are using too much air pressure.”
So how much pressure should you run? Zipp has this handy calculator that lets you input your body and bike weight, your wheel specs, your tire specs, and the riding surface then gives you front and rear tire pressure recommendations.
VeloNews received a test set of the 454 NSW wheels, and will post a review soon.