On Cloud X Review

March 13, 2018
On Cloud X
Ride Quality

The Good

  • Super lightweight
  • Excellent midsole response
  • Great ventilation in uppers

The Bad

  • High ankle collar
  • Midfoot slippage on track turns
  • Midsole too firm for regular long distances
The On Cloud X is a strong speed trainer or race shoe that may struggle with an identity problem if it marketed too heavily as a cross-training or gym shoe. Its midsole response is as good as any we’ve tested, and its sleek lightweight construction makes it easy to run fast. Fit might be an issue for some users, and long-term durability might be a problem for non-neutral runners in wearing down the pods asymmetrically.

The On Cloud X is an offshoot of the company’s model known just as the Cloud. Naming convention from the Swiss company gets a little bit tricky; the original Cloud model stays in the running lineup, along with the Cloud X, Cloudflow, and Cloudflyer, all of which are marketed as lightweight long-distance road shoes. It’s also very hard to distinguish specific performance profiles of the aforementioned models; for example, the Cloud X product page proclaims the “world’s lightest fully cushioned shoe for Running Remixed,” which is accompanied by a video of an athlete cross-training and running indoors.

Construction distinctions in the Cloud X compared to the Cloud include a revamped lace system, a thinner engineered mesh upper, and more extensive surface contact area underfoot with increased outsole rubber.  


The On Cloud X fits true to size in length and width. The last is slightly wide in the arch area, with adequate room across the metatarsal heads, and a toe box with enough height to avoid friction when flexing. One key improvement on this model is the use of a traditional lace system instead of the thin bungee system that was used on the original Cloud. The laces make it very easy to customize fit through the forefoot, but there are minimal overlay connections anchoring the laces to the midsole. We did experience a bit of slipping when going around track curves at high speeds.


The engineered mesh upper of the On Cloud X forefoot upper is extremely thin, and the soft dual-density sockliner underneath flexes and moves very easily with the foot, preventing any hot spots. The ankle collars sits slightly high, and are rigid on top, which could cause some discomfort at the ankle bones. Breathability through the forefoot is outstanding, and the midfoot saddle is thinner on the Cloud X than on the original Cloud. There is minimal padding around the heel and ankle collar, but an external plastic heel cup is substantial. This heel cup is fairly rigid, particularly in the Achilles area, but our testers still found the shoes comfortable to use right out of the box.  


The On Cloud X features the company’s signature CloudTec pods with hollow air-flow channels that provide individual load absorption and flexibility. The body of the pods is made with proprietary Zero-Gravity foam that is single-density for the length of the shoe. The air flow openings on the Cloud X are smaller than on other On models, with thicker foam surrounding them, which provides increased impact absorption and a softer ride. However, the material has very good energy return, and our testers all commented on the springy nature of this material to provide a firm bounce after initial impact as well as a nice push at toe-off. Some of this dynamic is also due to a stronger plastic spring plate that runs the length of the shoe between the cloud pods and the insole.

Ride Quality

The On Cloud X has a firm landing feel with smooth transition through the stance phase, and expanded surface area contact helps with ride quality in a couple of ways. First, the center decoupling channel that runs from heel to toe is much narrower on the Cloud X than on previous On models; this greatly reduces the likelihood of stones getting stuck in the midsole area when running on gravely roads. Additionally, the outsole rubber is more extensive in both the heel and forefoot areas in comparison to the Cloud, which provides a stable grip and good ground feel. Our testers felt that the

Cloud X lets your foot do exactly what it wants through the gait cycle, and the more robust underfoot construction should make it more durable for higher mileage outings or long training cycles.


If it isn’t obvious already, the On Cloud X is built for speed. It’s super lightweight, provides a firm and energetic midsole response, with secure grip and smooth flow from one stride to the next. It’s very easy to turn your legs over quickly, and we found ourselves setting improved mile splits in these shoes during speed sessions. They are ideal for road racing up to a half marathon distance, but their lack of cushioning may become an issue for marathon racing unless you’re accustomed to using minimalist footwear over long distances.


Testing of our lightweight road shoes was performed by a committee of testers, both male and female. Our group consists of eight testers who wore the shoes for total distances of approximately 20 to 80 miles. Single runs ranged in distance from three to 26 miles, and included casual training as well as speed workouts and road racing. The majority of our testing is conducted on asphalt roads or all-weather tracks, but we occasionally venture off-road onto jeep trails or smooth trails. Each tester prepares a summary overview of how each shoe performed in the criteria of fit, comfort, responsiveness, ride quality, and speed, and he or she also includes any additional thoughts or observations about the shoes during the test period.

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