Nike Alphafly 4: análisis y review

We put the Nike Alphafly 4 through extensive testing, as always, and found that it's:

• An instant buy for runners who loved the Alphafly 3 and after almost three years, just wanted something better. This is it.
• Perfect for marathon runners seeking a stable, responsive and fast super shoe.
• Ideal for those who struggle to get a secure lockdown in racing shoes.
• An excellent choice for heavier runners who generate plenty of force with every stride.

The Nike Alphafly 4 isn't the best super shoe for runners seeking a durable outsole that can also handle interval training and tempo runs. Our abrasion tests revealed poor wear resistance, while the PEBA-based midsole isn't ideal for piling on training miles. Instead, we recommend the PUMA Deviate Nitro Elite 4 or the Saucony Endorphin Pro 5.

We also believe the Alphafly 4 remains a bit too heavy, even with its weight-saving upgrades, especially considering how much other brands have progressed. The Nike Vaporfly 4 or ASICS Metaspeed Ray are our favorite alternatives at a similar price, while runners with deeper pockets may want to try to find a pair of the adidas Adizero Adios Pro Evo 3.

Shock absorption is especially important in a marathon shoe, and we were pleased to find that Nike delivers an improvement over its predecessor. Heel strikers get excellent impact protection with 157 SA, while the forefoot posts a more modest 117 SA.

But why is shock absorption noticeably lower in the forefoot? The answer lies in the Alphafly 4's unique construction, which combines two Air Zoom units with large foam cutouts that leave less material to absorb impacts. Nonetheless, 117 SA should still be enough for most of you, although we think heavier athletes may benefit from a shoe offering above +130 SA in the forefoot.

Nike fiiiiinally introduces a new foam, combining ZoomX LT (Pebax) with standard ZoomX (more Pebax) and Air Zoom units to deliver top-tier results. In our lab tests, we measured 79.9% energy return in the forefoot and 77.5% in the heel.

These are excellent numbers for a super shoe. Not quite state-of-the-art territory like the PUMA Fast-R Nitro Elite 3, but getting close to 80% is exactly what we expect from a flagship racer. Moreover, Nike actually delivered on its marketing claims about improved energy return over the Alphafly 3, something we don't always see from them.

Nike advertises a 39/31 mm stack height for the Alphafly 4, and our measurements matched the official heel specification perfectly at 39.0 mm.

The original Alphafly played a major role in prompting World Athletics to introduce its 40 mm stack height limit on January 31, 2020. Therefore, we're not surprised that Nike continues to push right up against that limit with the Alphafly 4, maximizing the amount of foam available underfoot.

The forefoot came in at 32.8 mm, exceeding Nike's stated 31 mm. That's also 10.8% taller than the forefoot we measured in the Alphafly 3.

This is a welcome change for runners who missed the higher forefoot stack of the beloved and iconic first-generation Alphafly.

Subtracting our forefoot measurement from the heel stack height gave us an actual drop of 6.2 mm, a bit lower than Nike's advertised 8 mm.

Therefore, the Alphafly 4 sits between the original model's 4-mm drop and the higher offsets of versions 2 and 3, bridging the gap between generations. We believe this change can be a net positive for midfoot and forefoot strikers who can benefit from this geometry.

Nike's new ZoomX LT joins conventional ZoomX in a dual-foam midsole that feels clearly softer than version 3. We measured 32.3 AC in our primary softness test (ZoomX LT) and 30.0 AC in the ZoomX foam. Both compounds land on the soft side, with only a small gap between our readings.

Many runners disliked the firmer ride of previous Alphafly models, and Nike clearly wanted to address that with version 4. The biggest change comes from the lower foam layer, which we found to be a massive 57% softer than before.

Finally, after our freezer test, the same foams became 17% and 4% firmer, respectively. Therefore, ZoomX maintained its softness better than ZoomX LT.

Nike has always taken a somewhat conservative approach to rocker geometry in its super shoes, with the Vaporfly remaining one of the more traditional racing shoes available today. The Alphafly 4 follows that same philosophy, featuring a late-rising forefoot rocker with a relatively modest upward curve.

Looking at the heel, we can see that Nike was clearly satisfied with the Alphafly 3's design, as the geometry remains almost unchanged. It features a heavily flared heel with a small bevel designed to encourage a more forward landing and reduce extreme heel strikes.

The carbon-fiber Flyplate also remains largely unchanged, featuring an extra-wide forefoot design that helps maximize compression of the two Air Zoom units positioned underneath, which is absolutely key to squeezing all the juice from any Alphafly.

The plate also retains a very similar curvature, dipping slightly through the midfoot before flattening out in the forefoot.

Nike claims that the updated Air Zoom units deliver improved energy return, and we certainly noticed differences between the Alphafly 3 (orange) and Alphafly 4 (blue). The new units are slightly smaller, feature more tensile fibers, and compress further than before.

However, the ride still feels very similar to previous generations. If you're the type of runner who loves sinking into plush foam before getting a springy rebound, you'll hate the Alpha 4. Instead, they deliver a mechanical, almost on-off sensation with limited compression and an instant, love-it-or-hate-it response.

Under our microscope, we found that ZoomX LT has a more elongated structure, while standard ZoomX features larger, rounded, bead-like particles. Nike places ZoomX LT above the carbon plate and pairs it with conventional ZoomX underneath.

According to Nike, the new manufacturing process behind ZoomX LT makes the foam up to 17% lighter while boosting energy return by 8%, and our lab results certainly seem to support those claims!

The Alphafly 4 measured 92.0 mm across the widest part of our gel replica. We found a snug racing fit across the ball of the foot, with less horizontal room than the average shoe.

This is exactly the kind of snug fit we expect from a racing shoe. However, with the Alphafly series, it's always worth highlighting that the Atomknit upper offers some stretch, making it more forgiving than the rigid mesh found in shoes like the Adios Pro 5.

At the big toe, we measured 72.2 mm of internal width. That's 4.1% narrower than the corresponding measurement in the Alphafly 3, so the fourth version gives up some of its predecessor's toe room. 

Vertical space tells a different story. Our gel replica measured 28.8 mm above the toes, giving the upper a more accommodating ceiling than its narrow footprint initially implies.

That's perfect for runners who dislike pressure over the tops of their toes, although it's worth remembering that extra height doesn't make up for limited space from side to side.

The Fast Shot outsole combines a catchy name with good grip, scoring 0.58 in our wet concrete test. We believe that's enough to make the Alphafly 4 your only super shoe, with reliable traction even when race day brings unexpected rain.

It's also a welcome improvement over the 0.40 recorded by the Alphafly 3. While that result wasn't terrible almost three years ago, competitors have made huge strides since then. So despite this welcome upgrade, we think that Nike still trails key rivals like ASICS, adidas, and PUMA when it comes to traction.

Turning the shoe over, we found most of the textured Fast Shot rubber concentrated under the forefoot. Two circular tread sections line up with the Air Zoom units, while redesigned openings expose the foam between the surrounding rubber.

The heel uses a very similar design from version 3, with two separated patches and a large central cutout that exposes the carbon Flyplate through the arch. We also noticed that this cutout is now wider and shorter than before.

Since the first Alphafly launched in 2020, this series has always demanded powerful legs to bend its wide, ultra-stiff carbon plate. That puts significant stress on the calves, but it can also deliver incredible efficiency gains for runners who take advantage of this aggressive geometry.

With version 4, we found that Nike dialed back the longitudinal stiffness slightly, making the shoe 14.1% more flexible than its predecessor. It required 24.4N in our 30-degree bend test, but it's still an extremely stiff shoe that may prove challenging for lighter or smaller runners.

The Nike Alphafly 4 weighed 6.7 oz (190g) in our men's US 9. That's 5.5% lighter than version 3, a welcome improvement while retaining the two Air Zoom units, full-length carbon Flyplate and delivering more shock absorption than before.

This result is far from the ultra-lightweight territory that has gained momentum since adidas introduced the Adios Pro Evo series in 2023. However, chasing the lowest possible weight has never been the Alphafly's approach to racing. That said, if you're a Nike-only runner who prioritizes a featherlight design, we recommend the Streakfly 2 for shorter races.

Despite making the Alphafly 4 softer than version 3, we found that its broad forefoot provides useful support around the Air Zoom units. Meanwhile, the midfoot cables integrated into the Atomknit upper help secure the foot, while the wide carbon Flyplate adds structure underneath.

For runners who loved the Alphafly 3 for being one of the most stable super shoes, version 4 certainly delivers. But how did Nike manage to maintain that stability despite making the midsole noticeably softer?

Our torsional rigidity test required 13.3 Nm of torque, revealing a moderate level of resistance to twisting. We believe this relatively low result comes mainly from the Alphafly 4's unique construction, which uses two Air Zoom units instead of a continuous layer of foam above the carbon plate.

We were able to fold the heel counter with almost no resistance, earning it the lowest score of 1/5. Like most super shoes, the Alphafly 4 skips a rigid heel shell in favor of a lightweight, race-focused construction that prioritizes performance over rearfoot support.

Using our digital calipers, we found that the Nike Alphafly 4 is marginally wider than version 3, with an increase of just 1.8 mm to reach 119.3 mm. We believe this broad platform is one of the main reasons why the Alphafly 4 feels more stable than many competing super shoes, although it also helps explain why Nike struggles to match the low weight of some rivals.

Where Nike made more noticeable changes is in the midfoot, which is now even wider to help offset the softer midsole introduced in version 4. And we felt that this approach definitely works, although it comes at the expense of some agility. After all, every running shoe design decision involves trade-offs.

The heel platform measured 89.4 mm, giving the rearfoot a more conventional amount of width compared to the average shoe but still very wide for racing-shoe standards.

The Atomknit upper finished with just 1/5 in our abrasion test, the lowest score available. We found very little resistance from the knit material, making this one of the shoe's most obvious and predictable weaknesses.

The heel lining performed better than the toebox, earning a respectable 3/5 in our Dremel durability test. Given how securely the shoe locks the heel in place, we don't believe this moderate result will be a concern for most runners.

We weren't impressed by the 2.9 mm dent left after our outsole abrasion test. That's a substantial amount of damage, making wear resistance one of the Alphafly 4's clearest drawbacks. We also tested two additional areas of the outsole, finding even deeper damage in the orange and black rubber sections, at 3.0 mm and 4.2 mm, respectively.

For us, this reinforces the case for treating the AF4 as dedicated racing equipment. Sure, it can be an amazing tempo shoe, but don't expect it to last forever. And it also confirms our suspicion that the legendary durability we all loved from the original Alphafly is unlikely to return, largely due to Nike's focus on reducing weight.

We measured just 1.8 mm of outsole rubber, finding a thin layer over the covered areas of the sole.

That keeps the outsole from becoming a bulky part of the construction, but leaves little extra material available for wear.

As expected, the Alphafly 4 earned a perfect 5/5 in our smoke test, with air moving freely through its Atomknit upper. We found ventilation to be a standout strength, giving runners an especially airy construction for warm marathons.

Our microscope images reveal huge openings between the yarns, with a very different structure from a densely covered training upper. It's great to see Nike continue refining the Atomknit upper, especially since it was already in a league of its own. In fact, keeping the excellent upper from version 3 would've been perfectly fine, but Nike decided to push things even further.

Nike pairs their signature textured laces with knit-based eyelets integrated into the upper, supported by cables through the midfoot.

We measured the tongue at 2.5 mm thick, providing light cushioning against lace pressure. We also like how Nike divided it into two sections, with extra padding at the top and a perforated lower section that helps improve ventilation.

The tongue is integrated into the Alphafly's signature sock-like upper, creating a foot-hugging fit that we believe is ideal for runners who dislike tongue movement. However, this fixed construction offers limited room for adjustment, making it a love-it-or-hate-it design.

The truth is that Nike continues to nail the fit of the Alphafly series, and version 4 might feature its best Atomknit upper yet. In our view, this is a real reason to choose the Alphafly 4 over competing super shoes.

The insole measured 3.0 mm, adding a slim layer directly beneath the foot.

We found the perforated insole glued in place, making it difficult to remove or replace. We managed to take it out for inspection, but the process was far from straightforward. Therefore, for the purposes of our lab testing, we classify it as non-removable.

The finger-loop heel tab makes the shoe easier to pull on, which we found especially useful given its sock-like construction. We're glad Nike decided to keep this practical feature despite its efforts to reduce weight wherever possible.

We confirmed that the Atomknit upper features reflective elements, a welcome addition that's rarely found in super shoes.

We appreciate the small price reduction, although the Alphafly 4 still requires a substantial investment. However, its impressive energy return, incredible Atomknit upper, and reduced weight make a convincing case for its performance, and we believe upgrading is a no-brainer for runners who loved the Alphafly 3.