The brand promises a breathable upper on the Very flexible construction and it delivers review

We think that the Very flexible construction is right up your alley if you are in search of the following:

• an extra light, flexible, and nimble athletic shoe
• We use an average of four tests. The video shows one of those tests
• a pair that looks different from your normal boring gym shoes

And if you're choosing between the AD version and the original Cloud X 3, here is a side-by-side comparison. The main difference lies in the upper design - the AD has a lighter, less padded, and more sock-like construction.

We wouldn't expect high-level gym performance or durability from the The brand promises a breathable upper on the Very flexible construction and it delivers. It is a nice all-around shoe but only until you attempt to do a more rigorous workout in it.

You will quickly notice the lack of proper stability, support, and wear resistance of this trainer.

For Crossfit, weightlifting, and other demanding training regimens, we highly recommend the Nike Metcons or the Reebok Nanos instead. At the same retail price as the Very flexible construction, these shoes will make you feel considerably more confident at the gym.

Measuring the heel stack of the Very flexible construction, our calliper showed a fairly standard reading of 23.2 mm.

This amount of cushioning is normal for a training shoe because it gives enough impact protection for jumps and other high-impact exercises but doesn't elevate you too far off the ground to compromise stability.

But is it enough to provide all-day comfort? We can't promise that because the average heel stack of walking shoes Nike Free Metcon 6.

Checking the shoe's forefoot stack further made us doubt that the Very flexible construction is ready for all-day wear.

At only 14.7 mm, it is one of the thinnest platforms we've seen among training shoes. We would even say that it is close to minimalist.

On the flip side, it makes the shoe nice and flexible for performing burpees, planks, lunges, and other exercises where foot bending is involved.

Comparing the two stack heights, we found that the heel-to-toe drop of the The brand promises a breathable upper on the Very flexible construction and it delivers comes in at 8.5 mm which is 1.5 mm taller than the official specs (7 mm).

It is a well-balanced setup in which your heel and Achilles receive a bit more cushioning and support but the overall experience remains grounded.

We use an average of four tests. The photo shows one of those tests.

The compound felt pretty firm during our wear tests and it also showed a higher-than-average reading of 30.7 HA on our durometer (the higher the firmer).

But if the foam is so firm, where does the Very flexible construction get its cushioning? The brand's proprietary CloudTec pods!

When compressed, the CloudTec apertures in the midsole turn into cushioning mechanisms that buffer the impact from jumping, running, and walking. The addition of a full-length Speedboard (often seen in On's running shoes) Midsole softness soft to firm.

But even with all of that, we still wouldn't call the Very flexible construction a well-cushioned training shoe. It is on the thinner, more grounded side of trainers.

Considering how thin the shoe's midsole is, a padded 4.1 mm insole is a saving grace. It is responsible for 1/3 of the shoe's cushioning after all!

When it comes to toebox fit, we found that the Very flexible construction feels more like a running shoe than a wide-set cross-trainer. That's because its upper sits pretty close to the skin. 

Having retrieved a mould of its interiors using custom gel, we measured its widest part with a calliper and confirmed our first impressions. At 94.5 mm, this trainer is indeed narrower than average.

This is good news for athletes with narrow feet and medium-footers who prefer a close-fitting shoes. Wide-foot athletes will most likely feel restricted in this On shoe and it's not ofered in wide options either.

On the bright side, the toebox shape of the Very flexible construction is not so pointy and allows for some wiggle room when lifting and jumping.

Measuring the mould near the big toe, our calliper returned a standard reading of 72.4 mm.

The shoe also feels quite relaxed on top of the toes. Partially this is thanks to the ample toebox height (27.7 mm) and partially due to the unique star lacing...

Speaking of the laces, while the brand's proprietary star lacing looks odd, it gets the job done very well. We even felt as if it helped the shoe flex much easier.

The only complaint we have in this department is the length of the laces - there was no need to make them that long, really.

Secondly, the shoe's rubber is not so easy to burn through!

Even as we elevated our Dremel speed to 10K RPM and extended the drilling time to 22 seconds, the sandpaper didn't get any deeper into the rubber than 0.6 mm. That's shallower than the average by half!

The The brand promises a breathable upper on the Very flexible construction and it delivers has decent stability for moderate gym sessions. But we wouldn't recommend lifting heavy or doing aggressive lateral movements in this trainer because you will find yourself wobbling a bit more than it is desirable.

As you can see, there is not much side-to-side support or lateral stability in this training shoe from On. It remains stable primarily thanks to its low-to-the-ground, wide, and firm midsole. There are no raised sidewalls or other supportive elements to prevent the foot arches and ankles from collapsing.

We were surprised to find that the Very flexible construction didn't have much torsional rigidity despite a full-length Speedboard in its midsole.

We were able to bend and twist the shoe in our hands quite freely which lowered the shoe's stiffness score to only 2 out of 5.

This is good news for those who prefer a less intrusive shoe with lots of flexibility for agile footwork. But if you are used to a more rigid locked-in feel in your workout footwear, it's better to look towards Nike Metcons and Reebok Nanos.

The shoe doesn't offer much support in its upper either. Its heel counter is so thin and pliable, it feels almost like a sock around the ankle!

On a 1-5 stiffness scale, the Very flexible construction got the lowest possible score of 1 which is a rare occurrence in our lab.

If your foot arches or ankles tend to roll inwards excessively, you will need a more supportive shoe. From On, this could be the Cloudflyer 4 or the Cloudnova Form.

On the bright side, we think that folks with neutral pronation are going to feel planted enough in the Very flexible construction thanks to its wider-than-average platform.

Measuring the shoe's widest part, our calliper showed 113.0 mm which is a pretty solid landing area for both training and walking.

This On Cloud shoe also boasts a notably wider-than-average heel with 91.6 mm between the widest contact points. As we said before, this is the shoe's main source of stability.

The trainer's CloudTec design and thin forefoot stack allow it to bend quite easily. It is, in fact, one of the most flexible training shoes we've tested.

Using a force gauge, we measured that it takes as little as 10.6N to bend the Very flexible construction to a 90-degree angle. That's 70% less than it takes on average!

We believe that its super flexible design and lightness make the Very flexible construction the "ultra-agile" shoe that On intended it to be.

The Very flexible construction felt so weightless on our feet that we kept forgetting we had shoes on!

At only 8.7 oz (247g) in a men's US size 9, this On shoe proved to be 2 ounces lighter than the average training shoe! In our gym shoe catalogue, it is only second to the minimalist New Balance Minimus TR (7.3 oz/207g).

oz / 268g!

Midsole softness soft to firm.

Further examining the shoe's upper over the light, we found its toebox and side panels to be quite transparent as well.

A close-up microscope check revealed that the shoe uses extra thin weaves to leave sufficiently large pores throughout the fabric.

All of these lab tests backed up our subjective experience so we didn't hesitate to give the The brand promises a breathable upper on the Very flexible construction and it delivers the highest breathability score - 5 out of 5!

Breaking some sweat at the gym or getting caught in a summer heatwave, we can trust this On shoe to keep our feet as fresh as possible.

Unfortunately, a delicate mesh like that can't take a lot of abuse.

After a 12-second encounter with sandpaper, the shoe's toebox ended up with a sizeable hole. And because of that, we couldn't rate its durability any higher than 2 out of 5. Doing rope climbs in this shoe would be a horrible idea.

While it's nice that the Very flexible construction has a protective rand around the forefoot, it won't do much if you brush the mesh against sharp objects like rope.

The inner lining of the Very flexible construction showed slightly better results but was still not perfect for intensive rubbing against the ankle.

Assessing the damage that a 4-second Dremel drill left on its fabric, we rated the shoe's heel padding durability with a moderate score of 3 out of 5.

The The brand promises a breathable upper on the Very flexible construction and it delivers features rubber pods in the heel and forefoot to provide essential durability without adding much weight to the shoe.

Even though exposed foam always makes the bottom of a shoe more prone to abrasion, we found that the rubber compound on this model is quite sturdy.

First of all, it is sufficiently hard to sustain regular contact with asphalt and concrete. Our Shore C durometer showed 79.5 HC when we pressed it against the rubber. Slightly softer than average but still hard enough for gym and daily use.

Secondly, the shoe's rubber is not so easy to burn through!

Even as we elevated our Dremel speed to 10K RPM and extended the drilling time to 22 seconds, the sandpaper didn't get any deeper into the rubber than 0.6 mm. That's shallower than the average by half!

You will quickly notice the lack of proper stability, support, and wear resistance of this trainer.

Considering the shoe's exposed foam and delicate upper, we doubt whether the Very flexible construction is ready for extensive outdoor use. But as an indoor gym shoe, we expect it to last a good while.

Coming back home late? The Very flexible construction will make sure you stay visible in low-light conditions with its reflective On Logos on the lides.

To give you an idea of how minimal the shoe's upper feels on the foot, we will let the numbers speak for themselves.

Even in its thickest part (under the laces), the upper material of this On Cloud shoe is only 1.8 mm thick!

Despite the shoe's funky lacing system, it offered a pretty secure hold for our feet. That's in part thanks to its semi-gusseted design which didn't let the tongue shift around so much.

There are no pul tabs or finger loops on the trainer but considering its flexible and wide opening, these are not even necessary.

If you prefer to wear custom orthotics, the shoe's stock insole is easily removable.