Our verdict

Nike enthusiasts have long awaited a Vaporfly for the trails, and the Ultrafly delivers, though with some unexpected twists. We can confirm that it combines a full-length ZoomX midsole, carbon plate, and Vibram Megagrip outsole for stellar performance, albeit a bit heavier than ideal. While its upper might not please all runners and the price is steep, in our tests, the Ultrafly stands out as a superb trail shoe, offering a plush ride and exceptional performance for long-distance training and racing.

Pros

  • Optimized for trail races
  • Accommodates wide feet with ease
  • Full-length, responsive Pebax midsole
  • Equipped with a Vibram Megagrip outsole
  • Ideal for long-distance training
  • Offers outstanding comfort
  • Remarkably stable
  • Suitable for 100-mile races

Cons

  • The Vaporweave upper could be more durable and breathable
  • Heavier than expected even for a trail racing shoe
  • The $260 price tag might be steep for some

Audience verdict

90
Superb!

Who should buy

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.

Nike Ultrafly

Who should NOT buy

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.

Nike Ultrafly

Breathability

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.

Nike Ultrafly microscope

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.

Nike Ultrafly microscope 2

Test results
Ultrafly 3
Average 3.3
Compared to 63 trail running shoes
Number of shoes
1
Breathability
5

Durability

Toebox durability

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 Ultrafly Toebox durability
Test results
Ultrafly 1
Average 2.9
Compared to 43 trail running shoes
Number of shoes
1
Toebox durability
5

Heel padding durability

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.

Nike Ultrafly Heel padding durability
Test results
Ultrafly 5
Average 2.8
Compared to 41 trail running shoes
Number of shoes
1
Heel padding durability
5

Outsole hardness

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.

Nike Ultrafly

The Megagrip Litebase outsole in a Nike shoe for the first time is a game-changing collaboration.

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

Nike Ultrafly Outsole hardness
Test results
Ultrafly 80.5 HC
Average 85.1 HC
We use an average of four tests. The photo shows one of those tests.
Compared to 86 trail running shoes
Number of shoes
72.5 HC
Outsole hardness
95.0 HC

Outsole durability

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.

Nike Ultrafly Outsole durability
Test results
Ultrafly 0.7 mm
Average 0.9 mm
Compared to 36 trail running shoes
Number of shoes
0.0 mm
Outsole wear
2.0 mm

Outsole thickness

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.

Nike Ultrafly Outsole thickness
Test results
Ultrafly 1.0 mm
Average 2.5 mm
Compared to 86 trail running shoes
Number of shoes
1.0 mm
Outsole thickness
6.5 mm

Weight

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.

Nike Ultrafly Weight
Test results
Ultrafly 10.55 oz (299g)
Average 10.37 oz (294g)
Compared to 86 trail running shoes
Number of shoes
7.51 oz (213g)
Weight
13.37 oz (379g)

Cushioning

Heel stack

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.

Nike Ultrafly Heel stack
Test results
Ultrafly 36.6 mm
Average 32.2 mm
Compared to 86 trail running shoes
Number of shoes
16.1 mm
Heel stack
40.4 mm

Forefoot stack

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 Ultrafly Forefoot stack
Test results
Ultrafly 24.8 mm
Average 24.3 mm
Compared to 86 trail running shoes
Number of shoes
15.2 mm
Forefoot stack
33.8 mm

Drop

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. 

Nike Ultrafly Drop
Test results
Ultrafly 11.8 mm
Average 8.1 mm
Compared to 85 trail running shoes
Number of shoes
0.1 mm
Drop
15.2 mm

Insole thickness

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.

Nike Ultrafly Insole thickness
Test results
Ultrafly 5.3 mm
Average 4.7 mm
Compared to 86 trail running shoes
Number of shoes
2.7 mm
Insole thickness
7.3 mm

Midsole softness

Note: a low durometer measurement equals a soft material, whereas a high measurement means it's firm.

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.

Nike Ultrafly Midsole softness
Test results
Ultrafly 9.8 HA
Average 26.3 HA
We use an average of four tests. The photo shows one of those tests.
Compared to 86 trail running shoes
Number of shoes
9.4 HA
Midsole softness (soft to firm)
50.3 HA

Midsole softness in cold

Note: a low durometer measurement equals a soft material, whereas a high measurement means it's firm.

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.

Nike Ultrafly Midsole softness in cold
Test results
Ultrafly 11.8 HA
Average 32.4 HA
Compared to 82 trail running shoes
Number of shoes
11.8 HA
Midsole softness in cold (soft to firm)
55.0 HA

Difference in midsole softness in cold

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.

Test results
Ultrafly 20.5%
Average 27.1%
Compared to 82 trail running shoes
Number of shoes
0%
Difference in midsole softness in cold
100%

Stability

Lateral stability test

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.

Torsional rigidity

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.

Test results
Ultrafly 5
Average 3.5
Compared to 80 trail running shoes
Number of shoes
1
Torsional rigidity
5

Heel counter stiffness

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.

Test results
Ultrafly 3
Average 3.2
Compared to 78 trail running shoes
Number of shoes
1
Heel counter stiffness
5

Midsole width in the forefoot

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.

Nike Ultrafly Midsole width in the forefoot
Test results
Ultrafly 122.1 mm
Average 111.7 mm
Compared to 86 trail running shoes
Number of shoes
102.1 mm
Midsole width in the forefoot
126.0 mm

Midsole width in the heel

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.

Nike Ultrafly Midsole width in the heel
Test results
Ultrafly 93.4 mm
Average 89.7 mm
Compared to 86 trail running shoes
Number of shoes
77.2 mm
Midsole width in the heel
109.3 mm

Flexibility

Stiffness

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.

Nike Ultrafly plate

Full-length carbon plates are rare in trail shoes, with most brands choosing shorter or forked plates.

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.

Test results
Ultrafly 40.5N
Average 29.3N
We use an average of four tests. The video shows one of those tests.
Compared to 86 trail running shoes
Number of shoes
10.5N
Stiffness
54.5N

Stiffness in cold

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.

Test results
Ultrafly 48.8N
Average 40.3N
Compared to 83 trail running shoes
Number of shoes
11.9N
Stiffness in cold
92.1N

Difference in stiffness in cold

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

Test results
Ultrafly 20.5%
Average 38.2%
Compared to 83 trail running shoes
Number of shoes
0%
Difference in stiffness in cold
102%

Grip / Traction

Lug depth

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.

Nike Ultrafly lugs

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

Nike Ultrafly Lug depth
Test results
Ultrafly 3.0 mm
Average 3.5 mm
Compared to 86 trail running shoes
Number of shoes
1.7 mm
Lug depth
5.8 mm

Size and fit

Toebox width at the widest part

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.

Nike Ultrafly toebox

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

Nike Ultrafly Toebox width at the widest part
Test results
Ultrafly 100.7 mm
Average 98.8 mm
Compared to 86 trail running shoes
Number of shoes
92.0 mm
Toebox width at the widest part
104.9 mm

Toebox width at the big toe

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.

Nike Ultrafly Toebox width at the big toe
Test results
Ultrafly 80.6 mm
Average 78.1 mm
Compared to 48 trail running shoes
Number of shoes
70.5 mm
Toebox width at the big toe
89.5 mm

Comfort

Tongue padding

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.

Nike Ultrafly padded tongue

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.

Nike Ultrafly Tongue padding
Test results
Ultrafly 6.1 mm
Average 6.3 mm
Compared to 86 trail running shoes
Number of shoes
1.5 mm
Tongue padding
12.2 mm

Heel tab

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.

Nike Ultrafly Heel tab
Test results
Ultrafly None

Removable insole

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.

Nike Ultrafly Removable insole
Test results
Ultrafly Yes

Misc

Reflective elements

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

Test results
Ultrafly Yes