The Nike Vaporfly 4% Flyknit Is An Update to Its Speed-Racing Shoe

A Flyknit upper makes the hard-to-get shoe even lighter and more breathable.

Type: Road Racing
The right shoe for: Competitive runners looking to go as fast as possible at distances up to the marathon.


A year after taking the running scene by storm with the Vaporfly 4%, Nike has released an update to the exceptionally fast racing shoe and greatly improved its fit while reducing weight. The Nike Vaporfly 4% Flyknit, as the name suggests, incorporates a new one-piece knit upper that seamlessly hugs the foot. The change from a lightweight mesh used on the previous version reduces irritation and improves breathabilty, too.

An All-New Upper

While everything under your foot remains the same, everything that wraps over the top has changed. The new Flyknit model uses a one-piece bootie-like construction that fits exceptionally snug around your foot. It’s definitely a racing fit, with a tapered design to contour to your midfoot and opening just enough in the front to accommodate your forefoot.


Nike Vaporfly 4% Flyknit
A Flyknit upper locks you onto the squishy soft midsole. Photo: Trevor Raab


The design is a lot like what we’ve seen on the Epic React Flyknit, but the knit used here is even less stretchy, which runners will appreciate as it bolsters support. The upper lacks any other typical reinforcements like overlays and a heel counter, but does have thinly padded patches and sueded materials inside to secure the foot to the soft platform.

The Springy Midsole Remains Unchanged

As noted, everything that you stand upon remains the same as Nike’s original version of this shoe. That means you’ll still get the thick slab of bouncy ZoomX foam, which in our lab tests on the original we saw delivered 80 percent energy return in the heel – the highest values we’ve ever measured in the lab.

That foam is paired with an extremely stiff carbon-fibre plate, which runs from heel to toe. The purpose of the plate is to extend push-off through the tips of the runner’s toes, essentially making it so the toes don’t bend – reducing the amount of energy the runner uses while increasing propulsive forces.

Nike Vaporfly 4% Flyknit
A limited amount of rubber is used to keep the weight down. Photo: Trevor Raab

Women: Size Up

The Vaporfly 4% is available in unisex sizing. That typically means a men’s 8 would be a women’s 9.5 (add 1.5 to the size). But our samples proved far too short for the women on staff. Our recommendation is to go up at least another half-size, or possibly even a full size. Men’s sizing seemed consistent among what we typically wear in Nike shoes.

A True Speed Racer

The Vaporfly has been controversial since its launch because it’s been shown to make runners faster – by making them, on average, four per cent more economical. There’s not a direct 1:1 correlation between running economy and speed, but data in a recent report by the New York Times found the shoe increased marathoners’ chances of earning a PB.

Our staff received samples of the new Vaporfly 4% Flyknit this week for testing, and the initial reactions among those who had never run in the Vaporfly before illustrate how the shoe differs from other models we’ve worn.

Nike Vaporfly 4% Flyknit
A carbon-fibre plate is embedded in the ZoomX midsole foam for a propulsive toe-off. Photo: Trevor Raab


“It feels incredibly bouncy,” says test editor Amanda Furrer. “The equivalent of Superman’s red cape, in which I become an alter-ego super-runner. It looks like a red neon flash on the track. You even feel zoomier walking in them.”

Gabriel Lodge, test editor for both Runner’s World and Bicycling, used them for a track workout. He reported that the shoe flowed smoothly as he motored along the backstretch of his last rep, cranking a 58-second 400 – a time considerably faster than he expected based on effort.

“They are the Bugatti Veyron of running shoes,” says special projects editor Kit Fox. “Yes, they will make you faster if you let the engines roar. But if you plan on just cruising through miles around the neighbourhood, it’s best to stick to a more reasonable model. Because like the Bugatti Veyron, they are ungodly expensive.”

BUY WOMEN’S              BUY MEN’S 


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