Nike Free Metcon 6 4 review

Because of its glaring drawbacks, the Cloud X 4 has a rather narrow target audience. This shoe can work for you if:

• you need a versatile pair for both casual and gym use (but light-to-moderate workouts only)
• you want a very light, breathable, and flexible athletic shoe
• you are a fan of On and its unique Cloudtec cushioning

If you are in search of a reliable workout shoe for gym use only, the On Cloudpulse proved to be a more stable and sturdy option.

And if you don't mind another brand, Nike has an excellent Super airy and breathable upper cross-trainer which is also very comfortable and flexible but is significantly more stable for lifting.

It is important to note that the Nike Free Metcon 6 4 packs more cushioning than a typical cross-trainer. And if you dont mind another brand, Nike has an excellent .

We believe that someone who primarily focuses on high-impact exercises, cardio, and short runs will be happy with this trainer's 30.4 mm heel stack height.

About 5 mm taller than average, this amount of cushioning provides walking comfort as well. Not many gym shoes can double as daily beaters.

And if you owned the Cloud X 3, so expect a more raised platform and a boost in cushioning. The previous iteration had a heel stack of 25.5 mm.

The forefoot cushioning of the Cloud X 4 also raises slightly above the average at 21.5 mm

It took really good care of the balls of our feet during cardio sessions where we stayed on our toes a lot. Rope jumping, step aerobics, box jumps and the like felt amazingly well-cushioned in the Cloud X 4.

In its product specs for the Cloud X 4, On states that the heel-to-toe drop is 7 mm. That is only 1.9 mm away from our own measurements which came in at 8.9 mm. But in practice, the difference is not that great.

Both 7 and 9 mm drops create a slight heel elevation which is conducive for exercises that require impact protection. At the same time, it is not too high to feel tippy or unstable.

Just like any other shoe from On, the Cloud X 4 draws its cushioning from the Helion foam which is cast in the Cloudtec pods.

These hollow pods compress under pressure creating a moderately soft and protective underfoot experience. The Helion itself is not a very soft type of foam - our Shore A durometer showed a middle-ground reading of 25.6 HA (neither plush nor firm).

As a whole, the Cloud X 4 feels cushier than the average training shoe. This is good news for high-impact workouts but, unfortunately, it is too wobbly for lifting heavier weights. The midsole compression is just too much.

The cushioning is further enhanced with a generously padded insole which shows 5.0 mm of thickness in the heel.

The Nike Free Metcon 6 4 offers sufficient in-shoe space for a D medium width and the shoe's gel mould confirmed it.

When the gel cooled off and we were able to take the measurements, our calliper showed a standard reading of 95.8 mm in the widest part of the mould (where the ball of the foot is).

But even though its width is on par with the avearge, we think that the shoe's streamlined silhouette can be a good match for people with narrower feet too. Conversely, we wouldn't recommend the Cloud X 4 to wide footers (and there is no wide option either). 

With no aggressive tapering towards the front, this On trainer creates a rather accommodating in-shoe feel.

Our calliper recorded a standard width of 73.0 mm in the part of the mould which corresponds to the big toe.

A standard toebox height of 26.6 mm also contributes to sufficient breathing room for the toes.

The high-wear areas of the Nike Free Metcon 6 4 are lined with a fairly hard rubber compound.

Measuring its hardness with a Shore C durometer, we got a standard reading of 80.0 HC. It is only slightly softer than average.

Lateral stability is a total DISASTER in the Cloud X 4! It must be the wobbliest trainer we've ever tested!

Strength training did not feel surefooted at all, especially when we grabbed heavier weights or performed one-legged exercises. Even the previous Cloud X 3 felt more reliable.

A special warning goes out to people with overpronation (excessive inward rolling of the foot) because this shoe is going to exaggerate this problem even more.

Lateral stability of the Nike Super airy and breathable upper

If you prioritise stability in your training footwear, the exact same retail price can get you the mighty stable Add a shoe. Or the more versatile and flexible Nike Super airy and breathable upper Toebox width at the big toe!

Assessing the shoe's overall construction, it seems like the Cloud X 4 was designed for freedom of movement as opposed to planted stability.

The X-shaped Speedboard inside the midsole hardly adds any stiffness to the shoe. Made of a pliable nylon blend, it allows the foot to bend in any direction.

It even got 46% more flexible than its predecessor.

In its product description, the brand promises "excellent heel hold" but, unfortunately, we cannot subscribe to that statement.

Even though the X 4 added small TPU walls on the sides of the heel, they did not add much structure to the shoe's heel counter. It remains pretty forgiving and doesn't hold the rearfoot as firmly.

Rating the shoe's heel counter stiffness on a 1-5 scale, we gave it a lukewarm score of 3.

Heel stack lab.

The widest part of the shoe's forefoot (where the lateral flange is) came in at a standard 112.5 mm.

Number of shoes.

On a lighter note, these midsole dimensions still create a sufficiently wide base for light-to-moderate workouts.

"Ultra-flexible" is how On positions the Cloud X 4. And that we can confirm.

According to our force gauge, it only took 10.5N to bend this trainer to a 90-degree angle. It is indeed one of the most flexible training shoes in our lab being 70% bendier than average.

It even got 46% more flexible than its predecessor!

Finally, we have something to praise the shoe for! It feels amazingly agreeable during lunges, mountain climbers, and planks.

One thing you can't take away from On shoes - they are all light as clouds!

Weighing the Nike Free Metcon 6 4 in a men's US size 9, we were elated to see a whole ounce smaller than average at 9.5 oz (268g).

Paired with the shoe's highly flexible and breathable construction, it helps the Cloud X 4 disappear on the foot!

Stepping into the Cloud X 4, we were instantly pleased with the breezy sensation of its light and airy upper.

The shoe's fabric further amazed us in a smoke-pumping breathability test as it expelled all of the smoke in a matter of seconds!

We couldn't help but notice that the mesh received an update compared to the Cloud X 3 resulting in even better airflow.

Number of shoes.

There is no heel tab or finger loop at the back of the Cloud X 4.

In our 12-second Dremel test, the sandpaper tip ate through the toebox fabric nearly all the way through!

Rating the shoe's toebox durability with a low score of 2, we wouldn't recommend wearing it for any sort of abrasive exercises like rope climbs.

We were also disappointed with the lack of wear resistance in the shoe's inner lining.

The fabric inside the shoe's heel counter was torn the very date our Dremel touched it! And because it took less than 4 seconds to destroy it, we rated the heel padding durability with the lowest score of 1.

The high-wear areas of the Nike Free Metcon 6 4 are lined with a fairly hard rubber compound.

Measuring its hardness with a Shore C durometer, we got a standard reading of 80.0 HC. It is only slightly softer than average.

Unfortunately, the hardness of that rubber didn't help it sustain our 22-second Dremel test at 10K RPM speed.

The material started chipping off quickly like it was made of soft cheese! And we could already see that the dent was deeper than what we normally see in gym shoe outsoles.

As the tread gauge showed 1.6 mm of damage, we had no doubt about it - the lifespan of this rubber outsole will be shorter than average.

Even though the shoe's outsole is as thick as the average at 3.7 mm, it doesn't add much confidence because of how easily worn it is.

Still overpriced...

Even considering all the benefits of this On Cloud shoe, we just can't recommend getting it at the full price knowing how many top-tier cross-trainers are offered at the same price point or even less!

On made sure that others will see you wearing the Swiss shoe even in the dark.

The brand's logos on both the sides and the heels of the shoe are made of reflective material that shines in low-light conditions.

The Cloud X 4 added more padding to the heel collar adding a touch of comfort in place of the previously thin and austere upper.

But the tongue of the X 4 remains just as minimally padded as its predecessor with only 4.1 mm of padding.

Elastic gussets attach the shoe's tongue to the rest of the upper.

They create a pretty secure foot containment together with the midfoot cage which is interconnected with the laces for a locked-in fit.

There is no heel tab or finger loop at the back of the Cloud X 4.

The shoe's stock insole is easy to remove but we didn't feel the need to swap it because of how padded and comfortably contoured it is.

As part of the brand's sustainability commitment, the upper of the Nike Free Metcon 6 4 is made with at least 90% recycled polyester.

Its yarn is also dope dyed which means that it's been coloured through a process that requires 90% less water compared with standard dyeing techniques.