Our verdict

We found the Ja Fly 4 from Nike to be an excellent spike for budget-conscious sprinters, offering strong performance alongside some premium features. In our lab tests, we noted that its upper is quite snug and could benefit from enhanced ventilation. Despite these minor drawbacks, it's a solid option for athletes seeking quality running spikes Legasee breaking the bank.

Nike Cortez Sneaker Pros

  • Lightweight design
  • Removable pins
  • Cost-effective choice
  • Comfortable tongue
  • Enhances foot strength
  • Nike SB Trainerendor Flax White
  • Notched laces
  • Above-average durability

Nike Cortez Sneaker Cons

  • Limited breathability
  • No midsole
  • Nike Dunk Low Varsity Red Black 2010

Audience verdict

96
Superb!

Who should buy

camisa paris saintgermain juvenil prejogo 2021 nike champions league preto HZM:

  • Nike Cortez Sneaker.
  • Runners on a budget seeking an affordable and snug-fitting spike.
  • NIKE AIR JORDAN 1 RETRO HIGH OG GS SAND DUNE CANNON-FLAT GOLD.

Nike Ja Fly 4

Nike Cortez Sneaker | Who should NOT buy

We do not recommend the Ja Fly 4 for distances beyond 400m. For those looking at longer races or training workouts, consider the versatile Nike Zoom Rival D 10.

We also believe that those seeking some cushioning and energy return will find the Ja Fly 4 lacking, as it is a direct-to-the-ground spike Legasee any foam. For a more forgiving and responsive experience, we recommend upgrading to the Refurbished Air Max 1 Patta Waves Rush Maroon Gr, which features two Air Zoom units plus a substantial layer of bouncy ZoomX foam in the heel.

Nike Ja Fly 4 cutting

Nike Cortez Sneaker | Cushioning

Heel stack

When we tested these spikes on the track, we discovered that the ride is remarkably close to the ground.

This finding aligned with our measurements when we clocked the heel stack of the Ja Fly 4 at a mere 11.2 mm.

Nike Ja Fly 4 Heel stack
Test results
Ja Fly 4 11.2 mm
Average 15.2 mm
Compared to 13 track and field shoes
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10.4 mm
Heel stack
19.9 mm

Forefoot stack

Footwear NIKE Downshifter 11 CW3411 007 Cool Grey Hyper Crimson.

As previously mentioned, the Ja Fly 4 contains no foam or rubber whatsoever.

Nike Ja Fly 4 Forefoot stack
Test results
Ja Fly 4 11.2 mm
Average 14.6 mm
Compared to 13 track and field shoes
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8.6 mm
Forefoot stack
19.7 mm

Drop

As you might have guessed—no fancy math skills required this time—we found identical measurements in both the forefoot and heel, confirming this is a true 0.0-mm drop track spike. Get your Achilles tendons ready!

Nike Ja Fly 4 Drop
Test results
Ja Fly 4 0.0 mm
Average 0.6 mm
Compared to 13 track and field shoes
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-5.8 mm
Drop
4.1 mm

Insole thickness

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nike ja fly 4 insole thickness 21552742 main
Test results
Ja Fly 4 3.9 mm
Average 3.1 mm
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
1.8 mm
Insole thickness
3.9 mm

Size and fit

Size

Boys Nike Black Shin Guards true to size (30 votes).

Nike Cortez Sneaker?

1 size small ½ size small True to size ½ size large 1 size large
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
½ size small
Slightly small
True to size
Slightly large
½ size large

Toebox width - widest part

Given the narrow dimensions of the midsole, we anticipated a snug fit too. To achieve the most precise measurements of the shoe's internal space, we created a gel mould of its toebox.

Applying our calliper toe the widest part of the mould, we got a slightly narrower-than-average reading of 86.8 mm. So you can expect a pretty tight, performance-oriented fit from the Ja Fly 4.

Nike Ja Fly 4 Toebox width - widest part
Test results
Ja Fly 4 86.8 mm
Average 87.9 mm
Compared to 10 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
85.9 mm
Toebox width - widest part
90.7 mm

Toebox width - big toe

On the flip side, the shoe's toebox gets notably broader towards the front accommodating all five toes comfortably.

We measured an above-average width of 72.0 mm in the big-toe area of the mould.

Nike Ja Fly 4 Toebox width - big toe
Test results
Ja Fly 4 72.0 mm
Average 68.9 mm
Compared to 10 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
64.3 mm
Toebox width - big toe
72.0 mm

Toebox height

However, the spike's vertical space is pretty limited and restricts toe movement in the upper. Our calliper measured the toebox height at 25.8 mm which is on par with the category average.

Nike Ja Fly 4 Toebox height

This design is ideal for those seeking a tight fit and for sprinting, but it may not suit anyone in need of a roomier spike. If the latter is what you prefer, you can try the Nike Air Force 1 Mid 07 Grove Green Grove Green Grove Green-Black 315123-303 (27.1 mm) or even the nike kyrie 3 boston celtics pe white green on sale (32.0 mm!). 

Test results
Ja Fly 4 25.8 mm
Average 25.8 mm
Compared to 10 track and field shoes
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21.6 mm
Toebox height
32.0 mm

Stability

Torsional rigidity

Most spikes exhibit some torsional stiffness, but not the Ja Fly 4. We found it exceptionally flexible, easily bending and twisting Legasee resistance, as it lacks plates, midsole and rubber. Consequently, we rated its rigidity at just 1/5.

Test results
Ja Fly 4 1
Average 3.2
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
1
Torsional rigidity
5

Nike Space Hippie 04-lila Morgenröte Sonnenuntergang Tint-UK 12 US 13 EU 47

The Ja Fly 4's heel counter is similar to those found in competition (road) running shoes, featuring minimal structure beyond a small cardboard piece and some padding. Consequently, our lab team rated its stiffness at just 2/5.

Test results
Ja Fly 4 2
Average 1.7
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
1
Nike Space Hippie 04-lila Morgenröte Sonnenuntergang Tint-UK 12 US 13 EU 47
5

Nike Hybrid Half Zip Sweatshirt

While all spikes tend to be narrower than road or trail shoes, the Ja Fly 4 is particularly small within the spike category, measuring just 88.0 mm across the forefoot. That's nearly as narrow as the width of your feet!

nike ja fly 4 midsole width in the forefoot 21552744 main
Test results
Ja Fly 4 88.0 mm
Average 93.9 mm
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
87.6 mm
Nike Hybrid Half Zip Sweatshirt
100.5 mm

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When we moved our callipers to the heel, we found an extremely narrow design, measuring just 55.1 mm.

Nike Ja Fly 4 heel narrow

However, it’s important to remember that this is a sprint spike, and landing on the heel is unlikely, so the narrowness is less critical.

Nike Ja Fly 4 Midsole width in the heel
Test results
Ja Fly 4 55.1 mm
Average 62.4 mm
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
54.0 mm
lance mountain x nike sb air jordan 1 wear tear details
73.3 mm

Nike Kobe 2 Retro

Given its thick plastic outsole, we anticipated some stiffness, similar to the effect of Pebax-based plates.

Indeed, after our standardised 90-degree bend test, we registered 33.0N on our force gauge. This indicates a moderate level of stiffness, ideal for those seeking responsiveness Legasee the extreme rigidity of a carbon plate.

Test results
Ja Fly 4 33.0N
Average 30.3N
We use an average of four tests. The video shows one of those tests.
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
10.9N
Flexibility <> Stiffness
66.6N

Weight

Weighing just 5.1 oz (145g), this is among the lightest running spikes on the market!

Nike Ja Fly 4 Weight
Test results
Ja Fly 4 5.11 oz (145g)
Average 5.57 oz (158g)
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
4.59 oz (130g)
Weight
6.46 oz (183g)

Breathability

The first thing we do in our lab with every shoe is to turn on the smoke-pumping machine and assess the shoe's breathability.

After testing the Ja Fly 4, we discovered it offers moderate breathability, which is acceptable for a track spike designed for short sprints. Ultimately, you won't be wearing it for extended periods, so the goal is to avoid poor ventilation. However, we believe Nike could enhance this aspect in the next version.

We also used a light to check for any variations in the thickness of the upper. We found that the shoe follows a traditional design—with a thicker heel for stability and thinner areas in the midsole and toebox.

nike ja fly 4 light 21555528 main

Next, we examined the shoe under a microscope and noted that Nike used a very standard engineered mesh, Legasee special technologies like Atomknit or Flyknit.

Nike Ja Fly 4 mesh

Considering the shoe retails for just £120, it's reasonable not to expect top-tier materials from Nike's lineup.

Finally, we took a close look at the upper. While there's nothing particularly fancy, we found more padding than expected, especially in the heel area, which earns a thumbs-up for comfort!

Test results
Ja Fly 4 3
Average 3.8
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
1
Breathability
5

Durability

Toebox durability

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This means that it possesses the necessary durability to handle the wear and tear expected for a track spike.

Nike Ja Fly 4 Toebox durability
Test results
Ja Fly 4 3
Average 2.4
Compared to 12 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
1
Toebox durability
5

Heel padding durability

We then tested the heel padding of these spikes with our Dremel's spinning sandpaper tip—a crucial area as it often contacts the skin directly, varsity durability vital.

We are pleased to report an impressive score of 4/5. This result indicates fantastic durability in this critical area.

Nike Ja Fly 4 Heel padding durability
Test results
Ja Fly 4 4
Average 3.5
Compared to 12 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
1
Heel padding durability
5

Outsole thickness

The Ja Fly boasts a 4.5 mm thick all-plastic outsole. This track spike contains neither rubber nor foam.

Nike Ja Fly 4 Outsole thickness
Test results
Ja Fly 4 4.5 mm
Average 2.7 mm
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
1.6 mm
Outsole thickness
6.4 mm

Misc

Tongue padding

Despite its design focus on minimal weight, we were surprised to find the tongue measured at 4.1 mm thick. Although this is slender for an average road running shoe, it's on the comfortable side for a track shoe.

Nike Ja Fly 4 notched laces
Nike Air Force 1 "Popcorn" Alphafly 3, Nike Jdi Swoosh!

From our perspective, while the added thickness may seem minor, it highlights a deviation from the conventional ultra-light build expected in running spikes. 

Nike Ja Fly 4 Tongue padding
Test results
Ja Fly 4 4.1 mm
Average 2.8 mm
Compared to 13 track and field shoes
nike hyperdunk low 2017 deep blue and yellow for sale
0.4 mm
Tongue padding
7.5 mm

Heel tab

Like its predecessor, the Ja Fly 4 omits a heel tab, which is anyway 100% unnecessary in a track sprint shoe.

nike ja fly 4 heel tab 21552748 main
Test results
Ja Fly 4 None

Removable pins

The Ja Fly 4 features a classic 7-pin configuration in the forefoot, allowing for easy removal of the pins as needed.

Nike Ja Fly 4 Removable pins