Our verdict

The On Cloud X sets itself apart from today's high-stack running shoes, embodying a multifaceted approach. We found it effortlessly adapts to everything from relaxed walks with your dog to easy and aerobic runs. Its versatility also shines in cross-training and gym workouts. However, we think long-distance runs may be a step too far for the Cloud X, due to its modest cushioning and firm midsole.

Pros

  • Versatile, do-it-all shoe
  • Durable, long-lasting outsole
  • Featherlight
  • Exceptionally comfortable
  • Precise, perfect fit
  • Superior build quality
  • Flexible and agile
  • Ground feel

Cons

  • On the pricier side
  • Lacks cushioning
  • Possesses a firm midsole

Audience verdict

89
Great!

Who should buy

The On Cloud X breaks the mould of the current trend in running shoes. We think it's ideal for those seeking a lightweight, low-stack versatile shoe, as it excels during aerobic runs, fast intervals, CrossFit, and even peaceful walks in the park.

And from our testing, we found it's specifically tailored for those who love firm midsoles.

On Cloud X

Who should NOT buy

In our view, if you're considering the On Cloud X for any long-distance runs, you might want to rethink that plan. Its significant lack of cushioning, similar to a minimalist shoe, makes it less suitable for these workouts. You'd be much better off choosing the On Cloudmonster.

Additionally, if you're a fan of plush midsoles, this shoe won't meet your expectations based on our lab tests. The foam is decidedly on the firm side, and alternatives like the ASICS Novablast 3 or the Brooks Ghost 15 would likely be a better fit for you.

On Cloud X

Breathability

The On Cloud X boasts a dual-layer engineered mesh upper, identical to the On Cloudstratus. Yet, it outperforms the latter in our smoke-pumping test, scoring an impressive 4 out of 5.

This result is further validated in the subsequent test. Light passes through the upper with ease, despite its dual-layer design.

This is due to the inner layer being thinner than in other On models, which lets heat and moisture escape.

On Cloud X microscope

Observing this layer under our microscope reveals its construction. The captivating images it provides also clarify why this shoe breathes better than we initially anticipated.

On Cloud X microscope

Finally, it was time for us to go all in with upper. With it ripped from the shoe, we can easily see how it's constructed.

If On had opted for a single layer, the shoe might have scored a perfect 5 out of 5 in our tests. However, this would likely have affected both durability and comfort.

Test results
Cloud X 4
Average 3.9
Compared to 185 running shoes
Number of shoes
1
Breathability
5

Durability

Toebox durability

Thanks to the innovative dual-layer design we mentioned earlier, the upper of this shoe truly shines in this test.

It even surpasses a majority of other shoes on the market, securing a fantastic score of 3 out of 5.

Test results
Cloud X 3
Average 2.1
Compared to 119 running shoes
Number of shoes
1
Toebox durability
5

Heel padding durability

However, the shoe's heel doesn't quite match up in terms of durability.

Nonetheless, we didn't have high expectations in that regard, as we noticed its plush feel. Experience tells us this typically results in a significant hole once the Dremel has had its way, and that's just what happened.

Test results
Cloud X 1
Average 2.9
Compared to 115 running shoes
Number of shoes
1
Heel padding durability
5

Outsole hardness

With a hardness of 82.1 HC, On utilizes a sturdy rubber to achieve enough outsole durability, a decision that makes perfect sense to us.

On Cloud X Outsole hardness
Test results
Cloud X 82.1 HC
Average 80.3 HC
We use an average of four tests. The photo shows one of those tests.
Compared to 237 running shoes
Number of shoes
55.5 HC
Outsole hardness
92.8 HC

Outsole durability

We engaged the Dremel for the last dance with this shoe, now focusing on the outsole.

The results were impressive: the machine only managed a slight 0.79 mm dent, indicating the rubber's high-quality performance and hinting at the shoe's potential long-lasting durability.

On Cloud X Outsole durability
Test results
Cloud X 0.8 mm
Average 0.9 mm
Compared to 97 running shoes
Number of shoes
0.0 mm
Outsole wear
2.0 mm

Outsole thickness

The outsole thickness of 3.0 mm might not seem substantial, but given its strong performance, we believe it should last for the entire lifespan of the shoe.

On Cloud X Outsole thickness
Test results
Cloud X 3.0 mm
Average 3.2 mm
Compared to 257 running shoes
Number of shoes
0.0 mm
Outsole thickness
6.6 mm

Weight

This shoe comes across as feather-light and it doesn't disappoint—our scale clocked it in at a mere 8.5 oz (240g)!

On Cloud X Weight
Test results
Cloud X 8.47 oz (240g)
Average 9.38 oz (266g)
Compared to 257 running shoes
Number of shoes
5.26 oz (149g)
Weight
12.56 oz (356g)

Cushioning

Heel stack

However, this lightweight design isn't due to an ultra-light upper, but rather from a limited stack height.

On Cloud X stack

At 27.9 mm, this shoe is quite low, so it doesn't provide ample cushioning for long distance runs. It's better suited for lighter runners who don't need large amounts of foam beneath their feet.

On Cloud X Heel stack
Test results
Cloud X 27.9 mm
Average 33.5 mm
Compared to 256 running shoes
Number of shoes
7.6 mm
Heel stack
42.7 mm

Forefoot stack

But if there's one thing that stands out, it's the severe shortage of foam in the forefoot.

On Cloud X forefoot

To measure the stack height, we follow the official World Athletics guidelines, which include the insole and outsole. Unfortunately, this leaves us with only a small amount of foam, and to make matters worse, not all of it is foam due to On's CloudTec system.

On Cloud X Forefoot stack
Test results
Cloud X 17.8 mm
Average 24.7 mm
Compared to 256 running shoes
Number of shoes
7.6 mm
Forefoot stack
34.8 mm

Drop

On claims that this shoe has a 6-mm heel-to-toe drop, but our measurements tell a very different story: 10.1 mm.

This is a disappointing outcome that can make you think twice about this shoe if you were counting on a moderate drop. Instead, the actual drop is really steep, which can be problematic for some runners seeking a more balanced and natural stride.

On Cloud X Drop
Test results
Cloud X 10.1 mm
Average 8.8 mm
Compared to 256 running shoes
Number of shoes
-0.8 mm
Drop
16.1 mm

Insole thickness

Inside the Cloud X, we found a pretty thick insole, likely trying to compensate for the lack of cushioning. We must acknowledge that it effectively fulfills that purpose.

On Cloud X Insole thickness
Test results
Cloud X 6.2 mm
Average 4.4 mm
Compared to 252 running shoes
Number of shoes
1.5 mm
Insole thickness
9.8 mm

Midsole softness

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

The Cloud X feels really firm from the moment you put them on your feet.

We were curious to quantify this feeling and compare it to other shoes in the market. The result was 33.5 HA, which is one of the firmest midsoles in the shelves.

On Cloud X Midsole softness
Test results
Cloud X 33.5 HA
Average 23.5 HA
We use an average of four tests. The photo shows one of those tests.
Compared to 238 running shoes
Number of shoes
6.5 HA
Midsole softness (soft to firm)
52.5 HA

Midsole softness in cold

Note: a low durometer measurement equals a soft material, whereas a high measurement means it's firm.
On Cloud X Midsole softness in cold

Difference in midsole softness in cold

After being exposed to 20 minutes of freezing temperatures, it becomes as hard as a brick, measuring at 40.4 HA. 

The Helion midsole of this shoe is made from EVA + Olefin Block Co-polymers. Thanks to this combination, the midsole can withstand cold temperatures impressively well.

In fact, it experiences only a 20.6% change in softness, which is better than what we typically see in other shoes.

On Cloud X Midsole softness in cold
Test results
Cloud X 20.6%
Average 26.4%
Compared to 237 running shoes
Number of shoes
0%
Difference in midsole softness in cold
125%

Stability

Lateral stability test

When you get a thin and firm midsole, you naturally expect the shoe to be stable. Fortunately, that's exactly the case with the Cloud X.

It remains steady and doesn't wobble at any pace, making it a delight for fans of low-stack stable running shoes!

Torsional rigidity

On promotes the Cloud X as a versatile model capable of running, cross-training, walking, and even being used as a lifestyle shoe.

To achieve that versatility, it needs to be flexible both longitudinally and torsionally. Regarding the latter, we found it to be sufficiently flexible and rated it at 2/5. Great!

Test results
Cloud X 2
Average 3.2
Compared to 234 running shoes
Number of shoes
1
Torsional rigidity
5

Heel counter stiffness

The same applies to the heel counter. It's not as hyper-flexible as the one you can find in racing shoes like the Adidas Adizero Adios Pro 3, but it's a bit firmer at 2/5, ensuring better lockdown without sacrificing comfort.

Test results
Cloud X 2
Average 2.7
Compared to 218 running shoes
Number of shoes
1
Heel counter stiffness
5

Midsole width in the forefoot

On likes to create stable shoes, and one way they achieve that is by making the landing platform wider than the average shoe. That's exactly what they did with the Cloud X, as we measured the width of the forefoot at a broad 115.5 mm.

On Cloud X Midsole width in the forefoot
Test results
Cloud X 115.5 mm
Average 113.4 mm
Compared to 257 running shoes
Number of shoes
100.5 mm
Midsole width in the forefoot
126.5 mm

Midsole width in the heel

The heel also feels stable and is not narrow at all; however, we can't consider it wide. It's just average at 91.7 mm.

On Cloud X Midsole width in the heel
Test results
Cloud X 91.7 mm
Average 90.2 mm
Compared to 257 running shoes
Number of shoes
74.9 mm
Midsole width in the heel
106.6 mm

Flexibility

Stiffness

For those seeking a flexible shoe, look no further. We only needed to produce 10.4N of force to bend it to 90 degrees, which is mind-blowing.

Test results
Cloud X 10.4N
Average 29.2N
We use an average of four tests. The video shows one of those tests.
Compared to 240 running shoes
Number of shoes
2.2N
Stiffness
94.4N

Difference in stiffness in cold

When exposed to cold temperatures, it became stiffer, requiring 19.0N of our force to bend it to the same point.

That's an 82.7% increase, which is extremely disappointing when compared to almost any other running shoe.

Test results
Cloud X 82.7%
Average 39.1%
Compared to 240 running shoes
Number of shoes
0%
Difference in stiffness in cold
148%

Size and fit

Internal length

On Cloud X Internal length

Toebox width at the widest part

With On designing the shoe as a versatile all-rounder, we anticipated it would comfortably accommodate wider fits. And it does!

Measuring at 102.7 mm, the shoe's upper provides ample room for nearly every foot shape.

On Cloud X Toebox width at the widest part
Test results
Cloud X 102.7 mm
Average 98.1 mm
Compared to 258 running shoes
Number of shoes
89.5 mm
Toebox width at the widest part
109.1 mm

Toebox width at the big toe

And it's not just the widest part of the shoe that impresses us, but also the toe cap. For those with square-shaped feet, the Cloud X emerges as one of the top choices on the market.

On Cloud X Toebox width at the big toe
Test results
Cloud X 81.7 mm
Average 77.8 mm
Compared to 130 running shoes
Number of shoes
67.6 mm
Toebox width at the big toe
90.4 mm

Tongue: gusset type

Like most On shoes, this model also features a bootie-like tongue.

On Cloud X Tongue: gusset type
Test results
Cloud X Bootie

Comfort

Tongue padding

On has designed this shoe with an emphasis on lightness, making a bulky, cushioned tongue impractical. They chose an average, balanced design instead, that we measured at 5.0 mm.

On Cloud X Tongue padding
Test results
Cloud X 5.0 mm
Average 5.7 mm
Compared to 254 running shoes
Number of shoes
0.5 mm
Tongue padding
14.2 mm

Heel tab

Regrettably, this On shoe lacks a heel tab, even though we can't say we anticipated one. It seems that the Swiss designers don't love this feature at all!

On Cloud X Heel tab
Test results
Cloud X None

Removable insole

One great feature of this On shoe is the removable insole. We were able to replace the original with our own orthotics without any issue.

On Cloud X Removable insole
Test results
Cloud X Yes

Misc

Reflective elements

This shoe surpasses at least 95% of the market in terms of reflective elements. Hats off to On for making safety a priority with their glowing logos!

On Cloud X Reflective elements
Test results
Cloud X Yes