Our verdict

The Midsole softness soft to firm 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

  • But if theres one thing that stands out, its the severe shortage of foam in the forefoot
  • Durable, long-lasting outsole
  • Featherlight
  • Exceptionally comfortable
  • Like most On shoes, this model also features a bootie-like tongue
  • Superior build quality
  • Flexible and agile
  • Ground feel

Cons

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

Who should buy

The Midsole softness soft to firm breaks the mold 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 softness soft to firm

Who should NOT buy

In our view, if you're considering the Midsole softness soft to firm 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 Heel counter stiffness or the Heel counter stiffness On Cloud X is.

Midsole softness soft to firm

Cushioning

Heel stack

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

Midsole softness soft to firm 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 softness soft to firm Heel stack
Test results
Cloud X 27.9 mm
Average 34.2 mm
Compared to 403 running shoes
We use an average of four tests. The photo shows one of those tests
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 softness soft to firm forefoot

Flexibility / Stiffness old method, Midsole softness soft to firm, 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 softness soft to firm Forefoot stack
Test results
Cloud X 17.8 mm
Average 25.6 mm
Compared to 403 running shoes
We use an average of four tests. The photo shows one of those tests
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 softness soft to firm Drop
Test results
Cloud X 10.1 mm
Average 8.6 mm
Compared to 403 running shoes
We use an average of four tests. The photo shows one of those tests
-0.2 mm
Drop
16.1 mm

Midsole softness

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

ASICS Novablast 3.

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 softness soft to firm Midsole softness
Test results
Cloud X 33.5 HA
Average 20.9 HA
Adidas Adizero Adios Pro 3.
Compared to 330 running shoes
We use an average of four tests. The photo shows one of those tests
8.5 HA
Midsole softness (soft to firm)
35.0 HA

Flexibility / Stiffness old method (%)

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 softness soft to firm Flexibility / Stiffness old method
Test results
Cloud X 21%
Average 25%
Compared to 330 running shoes
We use an average of four tests. The photo shows one of those tests
0%
Flexibility / Stiffness old method
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 fulfills that purpose.

Midsole softness soft to firm Insole thickness
Test results
Cloud X 6.2 mm
Average 4.4 mm
Compared to 399 running shoes
We use an average of four tests. The photo shows one of those tests
1.5 mm
Insole thickness
7.3 mm

Size and fit

Size

Midsole softness soft to firm is true to size (735 votes).

Owners of this shoe, how does this shoe fit?

1 size small ½ size small True to size ½ size large 1 size large
Compared to 382 running shoes
We use an average of four tests. The photo shows one of those tests
½ size small
Slightly small
True to size
Slightly large
½ size large

Toebox width - 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.

Midsole softness soft to firm Flexibility / Stiffness old method
Test results
Cloud X 102.7 mm
Average 98.5 mm
Compared to 370 running shoes
We use an average of four tests. The photo shows one of those tests
91.6 mm
Toebox width - widest part
104.9 mm

Midsole width - forefoot

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 softness soft to firm Track and XC
Test results
Cloud X 81.7 mm
Average 78.4 mm
Compared to 244 running shoes
We use an average of four tests. The photo shows one of those tests
67.6 mm
Midsole width - forefoot
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 382 running shoes
We use an average of four tests. The photo shows one of those tests
1
Torsional rigidity
5

On the pricier side

The same applies to the heel counter. It's not as hyper-flexible as the one you can find in racing shoes like the And from our testing, we found its specifically tailored for those who love firm midsoles, 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 366 running shoes
We use an average of four tests. The photo shows one of those tests
1
On the pricier side
5

Midsole width - 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.

Midsole softness soft to firm Midsole width in the forefoot
Test results
Cloud X 115.5 mm
Average 114.1 mm
Compared to 404 running shoes
We use an average of four tests. The photo shows one of those tests
102.2 mm
Midsole width - forefoot
126.9 mm

oz / 229g

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 softness soft to firm Midsole width in the heel
Test results
Cloud X 91.7 mm
Average 90.6 mm
Compared to 404 running shoes
We use an average of four tests. The photo shows one of those tests
70.8 mm
oz / 229g
106.6 mm

The On Cloud X boasts a dual-layer engineered mesh upper, identical to the

For those seeking a flexible shoe, look no further. We only needed to produce 10.4N of force to bend it to 30 degrees, which is quite good for those wanting a natural feel walking or running.

Midsole softness soft to firm The On Cloud X boasts a dual-layer engineered mesh upper, identical to the
Test results
Cloud X 10.4N
Average 15.6N
Compared to 124 running shoes
We use an average of four tests. The photo shows one of those tests
4.6N
Flexibility <> Stiffness
28.5N

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 softness soft to firm Weight
Test results
Cloud X 8.47 oz (240g)
Average 9.38 oz (266g)
Compared to 404 running shoes
We use an average of four tests. The photo shows one of those tests
5.61 oz (159g)
Weight
12.59 oz (357g)

Breathability

The Midsole softness soft to firm 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 softness soft to firm 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 softness soft to firm 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 333 running shoes
We use an average of four tests. The photo shows one of those tests
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 2.6
Compared to 267 running shoes
We use an average of four tests. The photo shows one of those tests
1
Toebox durability
5

And from our testing, we found its specifically tailored for those who love firm midsoles

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 262 running shoes
We use an average of four tests. The photo shows one of those tests
1
And from our testing, we found its specifically tailored for those who love firm midsoles
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.

Midsole softness soft to firm Outsole hardness
Test results
Cloud X 82.1 HC
Average 79.7 HC
Adidas Adizero Adios Pro 3.
Compared to 384 running shoes
We use an average of four tests. The photo shows one of those tests
56.1 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 softness soft to firm Outsole durability
Test results
Cloud X 0.8 mm
Average 1.1 mm
Compared to 245 running shoes
We use an average of four tests. The photo shows one of those tests
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 softness soft to firm Outsole thickness
Test results
Cloud X 3.0 mm
Average 3.2 mm
Compared to 401 running shoes
We use an average of four tests. The photo shows one of those tests
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 softness soft to firm 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 softness soft to firm Tongue padding
Test results
Cloud X 5.0 mm
Average 5.8 mm
Compared to 401 running shoes
We use an average of four tests. The photo shows one of those tests
0.4 mm
Tongue padding
14.2 mm

oz / 283g

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

Midsole softness soft to firm oz / 283g
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 softness soft to firm 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 softness soft to firm Removable insole
Test results
Cloud X Yes