Our verdict

We found the Cloud X 3 AD to be nearly identical to the regular X 3, except that it is even airier and bendier and its thinner upper fits more like a sock. With its highly flexible and agile construction, the trainer proved to be more appropriate for short runs and walks than other gym shoes we've tested. However, it fell short of stability when it came to serious strength training and weightlifting. Also, we would recommend waiting for a discount for the Cloud X 3 AD because, at this price point, you can get a flagship performance-oriented cross-trainer from other brands.

Pros

  • Versatile for gym use, casual wear, and short runs (up to 5K)
  • Incredibly light and agile on foot
  • Highly breathable upper
  • Very flexible construction
  • Wide and grounded sole
  • Upper feels like second skin
  • Fits true to size

Cons

  • Lacks durability for regular outdoor use
  • Not so cushioned for all-day wear
  • Very little side support (not for overpronation)

Audience verdict

84
Good!

Who should buy

We think that the Cloud X 3 AD is right up your alley if you are in search of the following:

  • an extra light, flexible, and nimble athletic shoe
  • a versatile trainer for daily walks, moderate gym sessions, and short runs
  • a pair that looks different from your normal boring gym shoes

On Cloud X 3 AD review

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.

On Cloud X 3 AD vs On Cloud X 3

Who should NOT buy

We wouldn't expect high-level gym performance or durability from the On Cloud X 3 AD. 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 Cloud X 3 AD, these shoes will make you feel considerably more confident at the gym.

On Cloud X 3 AD lab test

Cushioning

Heel stack

Measuring the heel stack of the Cloud X 3 AD, our calliper showed a fairly standard reading of 23.2 mm.

On Cloud X 3 AD Heel stack

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 hovers around 32-34 mm.

Test results
Cloud X 3 AD 23.2 mm
Average 24.8 mm
Compared to 41 training shoes
Number of shoes
13.7 mm
Heel stack
36.2 mm

Forefoot stack

Checking the shoe's forefoot stack further made us doubt that the Cloud X 3 AD is ready for all-day wear.

On Cloud X 3 AD Forefoot stack

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.

Test results
Cloud X 3 AD 14.7 mm
Average 18.4 mm
Compared to 41 training shoes
Number of shoes
10.6 mm
Forefoot stack
27.7 mm

Drop

Comparing the two stack heights, we found that the heel-to-toe drop of the On Cloud X 3 AD comes in at 8.5 mm which is 1.5 mm taller than the official specs (7 mm).

On Cloud X 3 AD Drop

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.

Test results
Cloud X 3 AD 8.5 mm
Average 6.4 mm
Compared to 41 training shoes
Number of shoes
1.8 mm
Drop
13.4 mm

Midsole softness

Note: a low durometer measurement equals a soft material, whereas a high measurement means it's firm.

This On Cloud shoe uses a single-density Helion foam for midsole cushioning.

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).

On Cloud X 3 AD Midsole softness

But if the foam is so firm, where does the Cloud X 3 AD 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) also contributed to a touch of bounce for the cardio bits of our workouts.

But even with all of that, we still wouldn't call the Cloud X 3 AD a well-cushioned training shoe. It is on the thinner, more grounded side of trainers.

Test results
Cloud X 3 AD 30.7 HA
Average 27.8 HA
We use an average of four tests. The photo shows one of those tests.
Compared to 41 training shoes
Number of shoes
17.4 HA
Midsole softness (soft to firm)
47.0 HA

Insole thickness

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!

On Cloud X 3 AD Insole thickness
Test results
Cloud X 3 AD 4.1 mm
Average 3.9 mm
Compared to 41 training shoes
Number of shoes
0.0 mm
Insole thickness
7.2 mm

Size and fit

Size

On Cloud X 3 AD is true to size (47 votes).

Owners of this shoe, how does this shoe fit?

Small True to size Large
Compared to 27 training shoes
Number of shoes
Small
True to size
Large

Toebox width - widest part

The Cloud X 3 AD also met our expectations in terms of the toebox fit. It is a perfect D medium width that is neither too spacious nor snug.

On Cloud X 3 AD Toebox width at the widest part

Measuring its widest part with a calliper returned 99.2 mm which is on par with the industry average.

Test results
Cloud X 3 AD 99.2 mm
Average 100.4 mm
Compared to 41 training shoes
Number of shoes
90.4 mm
Toebox width - widest part
108.5 mm

Toebox width - big toe

There is a very light tapering of the trainer's toebox towards the front but nothing too serious.

On Cloud X 3 AD Toebox width at the big toe

We measured the toebox at 77.3 mm in the big toe area and it also turned out to be the same as the average.

On Cloud X 3 AD fit

Test results
Cloud X 3 AD 77.3 mm
Average 78.8 mm
Compared to 34 training shoes
Number of shoes
65.0 mm
Toebox width - big toe
89.4 mm

Laces

Speaking of the laces... The Cloud X 3 AD uses the brand's proprietary "star" lacing which looks odd but gets the job done very well. We even felt as if it helped the shoe flex much easier.  

On Cloud X 3 AD laces

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

Stability

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!

On Cloud X 3 AD Outsole durability test

Lateral stability test

The On Cloud X 3 AD 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.

On Cloud X 3 AD medial support

Torsional rigidity

We were surprised to find that the Cloud X 3 AD 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.

Test results
Cloud X 3 AD 2
Average 2.7
Compared to 41 training shoes
Number of shoes
1
Torsional rigidity
5

Heel counter stiffness

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 Cloud X 3 AD 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 Cloud X 3 AD swiss engineering

Test results
Cloud X 3 AD 1
Average 2.7
Compared to 41 training shoes
Number of shoes
1
Heel counter stiffness
5

Midsole width - forefoot

On the bright side, we think that folks with neutral pronation are going to feel planted enough in the Cloud X 3 AD thanks to its wider-than-average platform.

On Cloud X 3 AD Midsole width in the forefoot

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

Test results
Cloud X 3 AD 113.0 mm
Average 110.6 mm
Compared to 41 training shoes
Number of shoes
101.0 mm
Midsole width - forefoot
117.9 mm

Midsole width - heel

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.

On Cloud X 3 AD Midsole width in the heel

Test results
Cloud X 3 AD 91.6 mm
Average 87.3 mm
Compared to 41 training shoes
Number of shoes
76.5 mm
Midsole width - heel
97.4 mm

Flexibility

Stiffness

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 Cloud X 3 AD to a 90-degree angle. That's 70% less than it takes on average!

On Cloud X 3 AD flexibility

We believe that its super flexible design and lightness make the Cloud X 3 AD the "ultra-agile" shoe that On intended it to be.

Test results
Cloud X 3 AD 10.6N
Average 17.8N
We use an average of four tests. The video shows one of those tests.
Compared to 41 training shoes
Number of shoes
4.3N
Stiffness
37.9N

Weight

The Cloud X 3 AD felt so weightless on our feet that we kept forgetting we had shoes on!

On Cloud X 3 AD Weight

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).

On Cloud X 3 AD lightweight

Test results
Cloud X 3 AD 8.71 oz (247g)
Average 10.76 oz (305g)
Compared to 41 training shoes
Number of shoes
6.38 oz (181g)
Weight
13.83 oz (392g)

Breathability

The brand promises a breathable upper on the Cloud X 3 AD and it delivers!

Pumping smoke into the shoe, we found that it passed through the toebox quickly and effortlessly.

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

On Cloud X 3 AD Breathability microscope test

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

On Cloud X 3 AD upper under microscope

All of these lab tests backed up our subjective experience so we didn't hesitate to give the On Cloud X 3 AD 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.

Test results
Cloud X 3 AD 5
Average 3.6
Compared to 41 training shoes
Number of shoes
1
Breathability
5

Durability

The Cloud X 3 AD also met our expectations in terms of the toebox fit. It is a perfect D medium width that is neither too spacious nor snug.

On Cloud X 3 AD Toebox width at the widest part

Measuring its widest part with a calliper returned 99.2 mm which is on par with the industry average.

Toebox durability

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.

On Cloud X 3 AD Toebox durability test

While it's nice that the Cloud X 3 AD has a protective rand around the forefoot, it won't do much if you brush the mesh against sharp objects like rope.

On Cloud X 3 AD toebox

Test results
Cloud X 3 AD 2
Average 2.5
Compared to 30 training shoes
Number of shoes
1
Toebox durability
5

Heel padding durability

The inner lining of the Cloud X 3 AD 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.

On Cloud X 3 AD Heel padding durability test
Test results
Cloud X 3 AD 3
Average 2.5
Compared to 28 training shoes
Number of shoes
1
Heel padding durability
5

Outsole hardness

The On Cloud X 3 AD features rubber pods in the heel and forefoot to provide essential durability without adding much weight to the shoe.

On Cloud X 3 AD outsole

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.

On Cloud X 3 AD Outsole hardness

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.

Test results
Cloud X 3 AD 79.5 HC
Average 83.0 HC
We use an average of four tests. The photo shows one of those tests.
Compared to 41 training shoes
Number of shoes
57.5 HC
Outsole hardness
94.5 HC

Outsole durability

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!

On Cloud X 3 AD Outsole durability test

Test results
Cloud X 3 AD 0.6 mm
Average 1.1 mm
Compared to 26 training shoes
Number of shoes
0.0 mm
Outsole wear
2.0 mm

Outsole thickness

However, the thickness of rubber on the Cloud X 3 AD proved to be thinner than average at 2.5 mm.

On Cloud X 3 AD Outsole thickness

Considering the shoe's exposed foam and delicate upper, we doubt whether the Cloud X 3 AD is ready for extensive outdoor use. But as an indoor gym shoe, we expect it to last a good while.

Test results
Cloud X 3 AD 2.5 mm
Average 3.6 mm
Compared to 41 training shoes
Number of shoes
0.0 mm
Outsole thickness
5.1 mm

Misc

Reflective elements

Coming back home late? The Cloud X 3 AD will make sure you stay visible in low-light conditions with its reflective On Logos on the lides.

Test results
Cloud X 3 AD Yes

Tongue padding

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

On Cloud X 3 AD Tongue padding

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

Test results
Cloud X 3 AD 1.8 mm
Average 5.4 mm
Compared to 41 training shoes
Number of shoes
1.0 mm
Tongue padding
10.4 mm

Tongue: gusset type

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.

On Cloud X 3 AD Tongue: gusset type
Test results
Cloud X 3 AD Both sides (semi)

Heel tab

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

On Cloud X 3 AD Heel tab
Test results
Cloud X 3 AD None

Removable insole

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

On Cloud X 3 AD Removable insole
Test results
Cloud X 3 AD Yes