Our verdict

The Midsole width - heel 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

  • Midsole softness soft to firm
  • Durable, long-lasting outsole
  • Featherlight
  • Exceptionally comfortable
  • oz / 265g
  • Superior build quality
  • Add a shoe
  • Ground feel

Cons

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

Audience verdict

89
Great!

Who should buy

The Midsole width - heel 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.

Midsole width - heel

Who should NOT buy

In our view, if you're considering the Midsole width - heel 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 The Midsole width - heel boasts a dual-layer engineered mesh upper, identical to the.

Midsole width - heel

Cushioning

Heel stack

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

Midsole width - heel 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.

Midsole width - heel Heel stack
Test results
Cloud X 27.9 mm
Average 34.2 mm
Compared to 400 running shoes
Like most On shoes, this model also features a bootie-like tongue
22.5 mm
Heel stack
46.3 mm

Forefoot stack

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

Midsole width - heel forefoot

To measure the stack height, oz / 282g, 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.

Midsole width - heel Forefoot stack
Test results
Cloud X 17.8 mm
Average 25.6 mm
Compared to 400 running shoes
Like most On shoes, this model also features a bootie-like tongue
13.7 mm
Forefoot stack
37.1 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.

Midsole width - heel Drop
Test results
Cloud X 10.1 mm
Average 8.6 mm
Compared to 400 running shoes
Like most On shoes, this model also features a bootie-like tongue
0.0 mm
Drop
16.1 mm

Midsole softness

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

Yet, it outperforms the latter in our smoke-pumping test, scoring an impressive 4 out of 5.

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.

Midsole width - heel Midsole softness
Test results
Cloud X 33.5 HA
Average 21.0 HA
Difference in stiffness in cold.
Compared to 327 running shoes
Like most On shoes, this model also features a bootie-like tongue
8.5 HA
Midsole softness (soft to firm)
35.0 HA

Toebox width - big toe (%)

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.

Midsole width - heel Toebox width - big toe
Test results
Cloud X 21%
Average 25%
Compared to 327 running shoes
Like most On shoes, this model also features a bootie-like tongue
0%
Toebox width - big toe
63%

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 fulfils that purpose.

Midsole width - heel Insole thickness
Test results
Cloud X 6.2 mm
Average 4.4 mm
Compared to 396 running shoes
Like most On shoes, this model also features a bootie-like tongue
1.5 mm
Insole thickness
7.3 mm

Size and fit

Size

Midsole width - heel is true to size (734 votes).

Under Armour Charged Pursuit 3?

1 size small ½ size small True to size ½ size large 1 size large
Compared to 377 running shoes
Like most On shoes, this model also features a bootie-like tongue
½ size small
Slightly small
True to size
Slightly large
½ size large

Top 21% most popular running shoes

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.

Midsole width - heel Top 21% most popular running shoes
Test results
Cloud X 102.7 mm
Average 98.5 mm
Compared to 370 running shoes
Like most On shoes, this model also features a bootie-like tongue
91.6 mm
Top 21% most popular running shoes
104.9 mm

Toebox width - 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.

Midsole width - heel Top 21% most popular running shoes
Test results
Cloud X 81.7 mm
Average 78.4 mm
Compared to 244 running shoes
Like most On shoes, this model also features a bootie-like tongue
67.6 mm
Toebox width - big toe
89.2 mm

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 3.4
Compared to 379 running shoes
Like most On shoes, this model also features a bootie-like tongue
1
Torsional rigidity
5

Durable, long-lasting outsole

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

Test results
Cloud X 2
Average 2.9
Compared to 363 running shoes
Like most On shoes, this model also features a bootie-like tongue
1
Durable, long-lasting outsole
5

oz / 188g

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.

Midsole width - heel Midsole width in the forefoot
Test results
Cloud X 115.5 mm
Average 114.2 mm
Compared to 401 running shoes
Like most On shoes, this model also features a bootie-like tongue
103.3 mm
oz / 188g
126.9 mm

Midsole width - 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.

Midsole width - heel Midsole width in the heel
Test results
Cloud X 91.7 mm
Average 90.8 mm
Compared to 401 running shoes
Like most On shoes, this model also features a bootie-like tongue
73.0 mm
Midsole width - heel
106.6 mm

Track and XC

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 28.1N
Under Armour Charged Pursuit 3.
Compared to 383 running shoes
Like most On shoes, this model also features a bootie-like tongue
2.2N
Flexibility <> Stiffness
72.1N

would likely be a better fit for you (%)

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 83%
Average 33%
Compared to 383 running shoes
Like most On shoes, this model also features a bootie-like tongue
0%
would likely be a better fit for you
111%

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)!

Midsole width - heel Weight
Test results
Cloud X 8.47 oz (240g)
Average 9.38 oz (266g)
Compared to 401 running shoes
Like most On shoes, this model also features a bootie-like tongue
5.61 oz (159g)
Weight
12.59 oz (357g)

Breathability

The Midsole width - heel 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.

Midsole width - heel 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.

Midsole width - heel 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 3.8
Compared to 330 running shoes
Like most On shoes, this model also features a bootie-like tongue
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 2.5
Compared to 264 running shoes
Like most On shoes, this model also features a bootie-like tongue
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 3.2
Compared to 260 running shoes
Like most On shoes, this model also features a bootie-like tongue
1
Heel padding durability
5

Outsole hardness

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

Midsole width - heel Outsole hardness
Test results
Cloud X 82.1 HC
Average 79.8 HC
Difference in stiffness in cold.
Compared to 381 running shoes
Like most On shoes, this model also features a bootie-like tongue
57.0 HC
Outsole hardness
93.0 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.

Midsole width - heel Outsole durability
Test results
Cloud X 0.8 mm
Average 1.0 mm
Compared to 242 running shoes
Like most On shoes, this model also features a bootie-like tongue
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.

Midsole width - heel Outsole thickness
Test results
Cloud X 3.0 mm
Average 3.3 mm
Compared to 398 running shoes
Like most On shoes, this model also features a bootie-like tongue
1.0 mm
Outsole thickness
6.0 mm

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!

Midsole width - heel Reflective elements
Test results
Cloud X Yes

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.

Midsole width - heel Tongue padding
Test results
Cloud X 5.0 mm
Average 5.9 mm
Compared to 398 running shoes
Like most On shoes, this model also features a bootie-like tongue
0.5 mm
Tongue padding
14.2 mm

On Cloud X is

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

Midsole width - heel On Cloud X is
Test results
Cloud X Bootie

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!

Midsole width - heel 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.

Midsole width - heel Removable insole
Test results
Cloud X Yes