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Pros

• The most cushioned running shoe
• Highly breathable
• Aggressive rocker midsole
• Highly responsive
• The best fun shoe

Cons

• It may feel heavy.
• The stack height is 50mm, which is not compliant with World Athletic rules.
• Unstable on the heels when running slow may be best suited for midfoot and forefoot striker
• Not versatile

Take Away

If Adizero Prime X were a car, it would probably be a Tesla because they exhibit advanced technological innovation. 

The Adizero Prime X is a shoe inspired by the Nike Alphafly Next% 2. Yet, it is an upgrade of Adidas Adios Pro 2.

It means that after the launch of Alphafly NEXT% in 2020, Nike elevated itself as the leader of advanced running shoe. Everyday, competitors are determined to outdo Nike.

 After the Nike Alphafly, New Balance came up with the TC and RC elite models, Saucony introduced the Endorphin Pro 2, and Hoka has Carbon X 2.

Adidas is not left behind shoe innovation. It has proven to adjust to shoe trends by producing a groundbreaking running shoe model, a direct competitor to the Alphafly Next%. But not on tracks or competition sanctioned by World Athletics.

Running shoes with soles thicker than 44mm or more than two embedded carbon plates will not be allowed in the World Olympics.

Recently, Adidas unveiled the Adizero Prime X. While we all thought this is the shoe that beats the Alphafly Next% hands down, Nike unveiled the Off-White x Nike Air Zoom Tempo NEXT% on July 26 2021.

The good thing is that while people did not get to see the Alphafly prototype used by Kipchoge to break the under 2 hours marathon record, the Adizero Prime X is available to any runner in the world at a whopping 50mm stack height.

It is easy to say that the Adidas Prime X is an illegal shoe that attracts curiosity.

Adidas Adizero Prime X Instant Impression

The idea that Adidas had launched a running shoe with a stack height of more than 50mm attracted my attention. My impression was centered on the thick, unstructured midsole and translucent upper the first time I saw the Prime X. I did not understand how a very thin upper material could complement a 50mm heel drop. The mega midsole gives it the wow factor.

I wear shoe size 10, but when I went for “true to size,” I felt a big gap in the forefoot and a poor lockdown around the heel, so I settled on a half a size down, and it fitted precisely.

The first time I put it on, the extra stack height was apparent. I felt like walking on stilts. It took a while to get used to walking in the Prime X. However, the more I walked around with the Prime X, the more I realized the magnified springiness of the LightStrike Pro midsole associated with Adios Pro 1, particularly in the heel zones.  

I took it out for a run and did a couple of interval speeds. The slow run felt quite uncomfortable because of the balancing issues, but I experienced much fun with speed work. At a fast pace, the carbon plate exploded, and the ride became soft and easy. The responsiveness of the midsole was also very profound, and the rocker forefoot worked magic to push me forward.

 I did about three to four minutes per kilometer effortlessly. I felt soft underfoot, and at 50mm stack, the Prime X felt exceptionally cushioned and at the same time with a slight ground feel.

Adizero Prime X Upper Design and Fitting

The Adizero Prime X took a minimalistic approach to its design. It has a smooth upper material with no overlays, giving it a soft feel and a 'cool' appearance. The upper is constructed with a translucent Celermesh 2.0 that has small perforations for breathability.

The Celermesh material stretches a little. Since it is extremely thin and smooth, it has a plastic-like feel. Apart from the sleek feel, the Celermesh does not absorb water.

The toe area has a smooth yet solid lamination that acts as a toe bumper. In addition, Adidas applied Nike's flywire technology in the first two eyelets to enhance grip. In essence, the mesh in Adizero Prime X has less internal web, which is only limited to strategic support bases in the lateral and medial sides of the toe box. It is for this reason that the mesh in Prime X is extremely thin and almost transparent.

Adidas Adizero Prime X comes with a flat and less padded tongue which is quite a letdown. The tongue also forms part of the lacing system. It is sewn to the eyelets to prevent it from moving sideways or downwards during running. Still, Adidas should have padded the tongue to enhance comfort in the upper foot.

When Running, I tend to feel irritation from the plastic reinforcing the first two eyelets. I also noticed Adidas made a miscalculation when sewing the tongue to the eyelets. The slit in the tongue which the laces run through is out of position.

Therefore, the tongue does not sit nicely above the foot. Instead, it tends to bunch up. Adidas should have positioned the slot slightly upwards.

The heel counter is relatively thin and unstructured. The collar is less solid but holds up pretty fine. The collar lining has a suede material to provide comfort. The foot lockdown is okay from the forefoot through to the midfoot. At the ankle, the lockdown is not 100%. I felt a slight heel slippage. Generally, the lack of a heel lockdown creates a free-floating feeling on the 55mm heel stack.

Overall the upper part is not so great because it is not 100% supportive and comfortable. The tightened laces exert pressure on top of the foot. You can loosen the laces, but it also means losing the support aspect. The arch lockdown is also quite sloppy, making the shoe quite unstable. For this reason, it does not pass as a cross-training shoe.

Adizero Prime X midose Component  and Performance

The Prime X has superior midsole cushioning than most daily trainers, including the Ghost 14. It is also probably the softest midsole I have ever encountered.

If you love the springiness and the cushioning of the LightStrike in the Adios pro, certainly you will not fail to like the intensified performance of the Prime X. 

Adidas retained the outstanding components of the Adios Pro, especially the curled atomic carbon rods in the forefoot. Also, a lot comes from the tuned-up midsole, so expect a softer midsole, intensified propulsion, and a more efficient forefoot rocker.

While retaining the three energy rods, Adidas added three curved carbon blades to make the forefoot rocker firmer and more profound. The energy rods keep the rocker firm, while the added carbon blades help enhance stability at the forefoot and make transitioning smooth and snappy despite the chunky midsole foam.

The marshmallow feels on the heel is apparent. Adidas compensated the high stack with a plate to provide stability but fell short of providing medial and lateral support. 

You then have to put your mind into your foot strikes at slow speed, stiffen the ankle to control stability. Run on a flat surface to prevent your ankles from rolling, and slow down when negotiating a corner.

It is strenuous if you are doing a slow pace long-distance marathon. The good news is that the beveled heel ensures that the ankle does not roll inwards if you are an overpronator. Surprisingly, the ride transitions to almost natural if you maintain a fast pace on a straight track or route.

 I tried various paces, especially five to four minutes per kilometer which is considered a good marathon pace. At such a running pace, I felt the ride to be very exciting because I exprienced the snappiness of the carbon plate at the midfoot.

The ride was soft and somehow gentle. With the late rocker forefoot, the transitioning from the midfoot to toe was very seamless. It felt like a rocker chair motion. It throws you forward. With a less supportive upper, the downside is that I always feel tired in the ankles each time I push for extra miles.

With a stack height of 55mm, one would have expected the shoe's bottom to be broader than the traditional shoe to give it additional stability. However, this is not the case with Adizero Prime X. It is a touch wider than a conventional running shoe.

The outsole is made of a standard Continental rubber. The impact is two-fold: Firstly, more durability, and secondly, somehow heavy underfoot.

Overall, it feels peppy running in Adizero Prime X. The rocker forefoot, carbon plate, and extra cushioning made the ride soft, seamless, and effortless. The Adizero Prime X feels like a long-distance marathon shoe. It may feel unstable during the slow run, but at a fast pace, everything falls into place.

I did not even think about my foot strikes. The foot tires, the running distance increases, and the more you experience the instability at the heel. It is advisable to stick with fast short distance running.

Why You Should Buy Adidas Prime X

The Prime X is a special shoe. It weighs less than the daily trainers like the Boston 10, Ghost 14, and Pegasus 38. Still, it offers superior cushioning, which is impressive. It is comparable to the Adios Pro, Fuel Cell RC Elite 2, Nike Tempo Next%, Nike Zoom X invincible Run, Asics Glide Ride, and Nike Alphafly. It is a breakneck competition.

The Prime X sticks slightly above with a more stable underfoot because of the hard Continental rubber, profound springiness, and superior vibration dampening.

Despite the technology thrown at it, the Prime X offers less assisted transition and is less versatile. You will not race with Adizero Prime X because it is somehow heavy and not very responsive. However, if you are looking for fast short marathon training, it is a got-to shoe.

You can rack up miles with it if you are a runner who does not need support shoes. The rocker offers an excellent energy return while the cushioning pampers the foot throughput the long distance.

Personally, despite various shoe options in the market, I am determined to retain Adizero Prime X as a rotation training shoe, especially for a fast marathon training day.  

It means that Adizero Prime X is not for someone with limited shoe options. Instead, it is more of a companion and a fun shoe because you won't walk with it or use it on easy days.

 I still believe that given a chance to participate in the Tokyo Olympics, the Prime X would have broken records in the 800 or 1500 meters.

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Reviewed by Bruce Cavette

Bruce Cavette is an ardent runner and a shoe lover.  He likes to stretch his training into miles, so he does nothing short of a 5k.