Nike Ultrafly review

Based on our lab tests, the eagerly anticipated Nike Ultrafly is a top pick for:

• Nike aficionados seeking the plush, incredibly-propulsive ZoomX experience on the trails.
• Ultra-marathoners looking for the ultimate racing shoe.
• Trail runners with a flexible budget who desire a high-performance shoe providing both comfort and speed.

If you're after an ultra-light trail racing shoe, the Nike Ultrafly might not be the one. Tipping the scales at over 10 ounces in our lab, it doesn’t exactly feel lightweight. For something much lighter, consider the Hoka Zinal 2, or for a more balanced approach between cushioning and weight, the Saucony Endorphin Edge.

Additionally, the Ultrafly comes with a hefty price tag. If you're looking to save some money and don't mind a slightly less responsive midsole, we suggest excellent well-rounded alternatives like the Brooks Cascadia 17 or the Saucony Peregrine 13 available in the market.

If you're in search of a cushioned trail running shoe, your search ends here. With a thickness of 36.6 mm, it stands as one of the thickest models on the market, and performs phenomenally in this aspect. The miles just seem to effortlessly roll by in every long run.

In the forefoot, the stack height is 24.8 mm, which is the average for trail shoes.

Although some runners might desire extra cushioning in this area for an ultra-distance shoe, we believe the current amount is sufficient in the Ultrafly. Adding more foam would have increased the weight of an already heavy shoe unnecessarily.

Nike claims an 8.5-mm drop, but our measurement shows 11.8 mm. Wondering why such a discrepancy occurs? We've got an advanced, in-depth explanation to clear things up.

While it may seem higher than usual in trail shoes, it feels slightly less steep underfoot because of its geometry, and it's a marvel for heel strikers. 

Accustomed to firm, brick-like trail midsoles, the Ultrafly provides a cloud-like experience like no other.

With a durometer of just 9.8 HA, its full-length, Pebax-based ZoomX midsole offers world-class energy return.

There is a caveat, though. The forked carbon plate embedded in the midfoot results in a slightly firmer feel than the durometer reading suggests. However, this also contributes added stability and snappiness to the shoe.

We tested the Ultrafly in the lab to simulate those cold, bone-chilling winter runs and then remeasured its softness. Our durometer showed a result of 11.8 HA.

Given that ZoomX is a Pebax-based midsole, it was crystal clear that it would excel (+20.5%) even after being exposed to cold temperatures. We go deep into this in our advanced guide on the topic.

The insole is very cushioned, contributing to the overall plush and comfortable feel during runs. While the Ultrafly it's a bit heavy for a racing shoe, it's important to note that the extra weight is entirely devoted to enhancing comfort.

With the massive width of the midsole, we anticipated a wide toebox—yes, even for a Nike shoe. And we weren't disappointed! Measuring 100.7 mm, this shoe is clearly designed for those with regular and wide feet.

Runners with narrow feet might prefer exploring a narrower yet still blazing-fast option like the Hoka Speedgoat 5.

In the big toe area, we measured 80.6 mm, perfectly aligning with the shoe's wide design.

With such dimensions, Nike ensures runners have ample opportunity for toe splay inside the toebox, and we loved it.

With its impressive height and plush feel, it seemed unlikely that this shoe would rank as one of the most stable in trail running.

However, we can confidently say it's far more stable than anyone might expect before trying it out. We will show you how Nike accomplished this feat.

The primary method they've used is incorporating an ultra-stiff, forked carbon plate, which lead to a 5/5 in our manual assessment about torsional rigidity.

While this might compromise comfort somewhat, it proves to be a game-changer for stability, particularly in shoes like this, with an exceptionally soft midsole.

The heel counter features moderate stiffness at 3/5, adding to the overall increase in stability, and it's clear that Nike still has a few more tricks up its sleeve if needed.

The key factor behind the shoe's considerable weight and exceptional stability is its impressively wide midsole.

Measuring 122.1 mm in the forefoot, Nike's designers recognized the need for dimensions beyond what a Vaporfly offers to suit trail conditions effectively.

Similarly, in the heel, the shoe outshines nearly all other trail shoes with a width of 93.4 mm.

This ensures that the shoe accommodates all footstrikes with proper stability, regardless of whether you land towards the front or back of your feet.

This shoe underwent a seemingly endless development period. We spotted it being tested in the wild almost two years before its release, and we're aware that its forked plate underwent numerous changes during development.

The Ultrafly follows that trend featuring a midfoot plate that adds exceptional stiffness to the shoe, surpassing even our expectations. However, it's not a full-length carbon plate, although it goes longer than it seems in the image because of its forked shape.

In our 90-degree bend test, it required a substantial 40.5N of force to bend the shoe.

We followed the same procedure as with the midsole softness test—a 20-minute pause followed by another measurement.

This time, the shoe registered a higher stiffness at 48.8N.

This represents a 20.5% increase in stiffness, a positive outcome that aligns with our expectations for a premium foam like ZoomX.

Despite Nike efforts, the most disappointing aspect of this shoe is definitely its weight.

Weighing in at 10.5 oz (299g), it's excessively heavy for a racing shoe, especially one with a Vaporweave upper. We're confident that Nike has the capability to significantly improve in this regard, so hopefully, we'll see a lighter version in version 2.

The much-anticipated Ultrafly arrived with a big surprise, featuring Vaporweave—a technology that seemed to have been abandoned by Nike after its debut in the first-generation Vaporfly.

Vaporweave is an ultra-thin mesh that faced criticism for poor breathability. So, our expectations weren't high before testing, particularly because the Ultrafly combines this mesh with a comfort-focused fabric underneath as can be seen in the video above.

However, the Ultrafly earned a 3/5 in our smoke-pumping test, which is not a bad result for this type of plasticky upper.

Using a light, we confirmed that the Vaporweave upper doesn't have any big breathability holes, a common feature in trail running shoes.

Under the microscope, we discovered some tiny holes responsible for the shoe's average breathability score. Without these holes, the shoe would have likely scored a 1/5.

Durability is crucial for trail shoes, yet the Vaporweave upper of the Ultrafly disappoints in this regard. Without any significant protective strips, it offers little resistance, scoring a mere 1/5 in our Dremel test.

However, it's important to note that this shoe isn't designed for harsh, rocky technical terrains, but rather for ultra running on easier trails. In such conditions, the lack of durability isn't as critical, but it's a notable compromise for a trail shoe anyway.

Nike has done a fantastic job enhancing the heel padding durability in their racing shoes, and the Ultrafly, much like its road sibling, the Vaporfly 3, reaps the benefits.

Our Dremel test yielded an impressive 5/5 result, setting a benchmark that other brands should definitely consider.

Runners often criticized Nike outsoles for their poor grip and quality. However, those days are behind us with the Ultrafly because the Oregon-based brand has FINALLY teamed up with Vibram.

Our measurements confirmed what we anticipated, with the outsole coming in just below average for trail shoes, at 80.5 HC.

Vibram outsoles are known for their solid performance in durability, and the results of our third Dremel test did not disappoint.

We observed a mere 0.7 mm dent after this rigorous test, a result that is positively encouraging.

Accustomed as we are to ultra-rugged trail running shoes, this one stands apart.

The Ultrafly offers outstanding grip on flat terrain.

With an outsole measuring just 1.0 mm, it's quite thin, aiming for weight reduction. However, you can expect sufficient durability, thanks to the proven toughness of the Vibram rubber.

One crucial feature of any trail shoe is the lugs. The Ultrafly features short 3.0-mm lugs, designed for easy trails and fast running but not specifically for technical or muddy terrain.

However, the lugs on this Vibram outsole are certainly capable of handling more challenging areas when necessary.

Nike has added some reflective elements to the Ultrafly, but we believe they could enhance this feature. Perhaps incorporating a reflective swoosh?

Designed mainly for ultra-marathons like the Western States Endurance Run, it was almost essential for Nike to include a plush, comfort-focused tongue in this shoe. It helps prevent lace bite and similar issues.

While this feature impacts the shoe's weight, we believe Nike could have opted for a 3-to-4-mm tongue instead of the 6.1 mm one. However, unlike in road running, most trail runners will likely appreciate the extra padding of the tongue, even if it means a few additional grams.

The Ultrafly doesn't have a heel tab, but Nike has added a cool touch by incorporating a sleek plastic piece featuring their trail running logo.

The insole is removable, and thanks to the generous dimensions of both the midsole and upper, there’s ample room to accommodate insoles from other shoes or custom orthotics with ease.