Wednesday, March 03, 2021

ON Running Cloudultra Review

Article by Bryan Lim

ON Running Cloudultra ($180 US)

Update: Please read our full multi tester review (including Bryan's take here


Founded in Zurich in 2010, On only entered the Australian market 3 years ago. To mirror this, the Cloudultra is my third pair of On shoes following the original Cloud and the recently released Cloudswift. The Cloudultra is designed for, as suggested, ultra-distances. Quoting our Editor-in-chief Sam, all On shoes have distinctive CloudTec elements which deflect on impact and lock on push off rebounding independently of each other. The Cloudultra features two layers of Clouds. Above the Cloudtec Elements or cloud pods, there is a Speedboard plate to accentuate the rolling motion of the foot and the Cloudultra features a wider plate in the shank area for support. Probably the most unique feature that caught my eye is the intuitive FlipRelease tool found in the lower lacing, where flipping the plastic construct provides an option for variable lacing width and pressure release at the forefoot. Note there are only two width ‘settings’.

Pros and Cons

Pros: Solid traction, brilliant craftsmanship, durable

Cons: Narrow fit (I fit into narrow shoes such as the Adidas Adizero Adios 3 with ease), firm ride, heavy

Tester Profile

Bryan is a road and trail runner living in Melbourne, Australia. He is a consistent sub 1:25 half marathoner and is presently chasing a sub 3-hour marathon. He is 176cm/ 5'9" tall and weighs about 65kg / 143lbs. 


Weight: men's 10.69 oz / 303g (US9)  

Official: 295g / 10.5 oz (M US8.5)   

  Samples: men’s 303g / 10.69 oz (M9)

Stack Height: 8mm drop

Available: 04 March 2021 


First Impressions and Fit

Having limited exposure to On running shoes, with the most miles clocked in the Cloudswift just a week before, I was skeptical but limited in my impression of the CloudTec technology but concerned about the firmness of the new Helion midsole.

Like all other On shoes on my product tour at the Australian On office, the Cloudultra feel very different than any other trail shoe I’ve worn. It almost exudes an exquisite vibe about it, so much so that I broke into them by wearing them to the office! The shoe is specifically designed in every way with no corners cut, from the sock-like two layer sandwich mesh upper to the dual layered Cloud pods that are smaller and said to provide more cushioning and long run comfort and I hope to prevent grit from being trapped in them. 

That said, the fit was true to size in a M9. I found the fit to be narrow especially for a shoe designed for the ultra, and one that specifically targets swelling feet associated with time on feet. Perhaps, more time is needed to stretch out the slightly stretchable sock fit with the FlipRelease tool to relieve forefoot pressure also in the mix and to be considered . With the luxury of also trying on a M9.5, I can confirm the M9 (my usual size) was correct.


There’s so much about the upper to like, but my initial concern is the already mentioned narrow fit and tightness in the dorsal side of my foot caused by likely not yet stretched out semi-elastic meshed sock fit and the additional elastic band that reinforces the sock fit, as seen in the image below as the white band that crosses the middle eyelet. 

PC: ON Running 

In providing a dialed in fit, they ironically work against the Cloudultra's main feature, the FlipRelease, a plastic one piece construct seen above below the white band on the laces that an at the flip of the switch significantly widens the lower lacing when your feet swell during a long distance run. I found myself tying my laces looser than usual due to the narrow and slightly restrictive fit. 

The simple yet potentially effective FlipRelease is a plastic one piece construct that significantly widens the lower lacing

Putting that aside, the upper features a myriad of elements on top of the aforementioned sock fit, there’s another layer of closed mesh, rubber overlays that seamlessly transitions into a reinforced heel cup and to the toe box up front. 

Seamless transitioning of a thin rubber overlay on the lateral and medial sides into a thicker and denser one that forms the reinforced heel cup

What seems to be a cleverly engineered upper provides a dialed in and confident fit for technical trails. On 15% climbs, I did not notice any heel slippage.

Rubber overlays run around the shoe with the sleek integration of a reinforced toe box


PC: ON Running 

The Cloudultra uses On’s new Helion foam which is supposed to be softer and more temperature resistant. Compared to the midsole used in the original On Cloud, it is definitely softer, albeit still very firm for an ultra-shoe with a reasonable stack height. The ride, from toe-off to transition is firm likely due to the Speedboard used. Again, quoting our Editor-in-chief, the Speedboard is a full length plastic plate designed to accentuate the rolling motion of the foot. 

Unlike the Cloudswift, which is made for road running and features a rocker, the utilisation of the Speedboard is questionable. Clearly not meant to be a rock plate, the Speedboard sits high up in the midsole below the insole, which contributes greatly to its firm ride.

PC: ON Running 

The midsole also features a pronounced rocker that is useful on steep ascents, keeping the runner on toe and engaged. The rocker also provides some relief from the rigid Speedboard in allowing for a confident toe off.

Smaller than usual pods at two varying heights cushion and mitigate grit and debris from being trapped

Two layers of Cloud pods are claimed to provide more cushioning for long distance running. With the smaller than usual pods, there appears to be a thin layer of traditional midsole above the pods. Whilst the stack height provides for ample cushioning and protection, the Speedboard seems to mute it by instead imposing the firm ride as well as torsional rigidity that was appreciated on uneven terrain and steep climbs. Compared to the construct of the Helion midsole used in the new Cloudswift, the Cloudultra presents with a much firmer ride.

My main concern about the midsole and On shoes in general remains the potential for stones and general debris to be caught within the cloud pods. Uniquely shaped in the Cloudultra, it would be a challenge to remove caught material in the pods mid run.


PC: ON Running 

Unlike On’s road fleet of shoes, the Cloudultra is unique in having “connected clouds” i.e. a regular looking outsole that does not feature deep grooves that will attract stones and debris to get caught within them. 

PC: On Running

The pattern from toe to heel can be broken down into four segments, see image above. From the heel, we have very shallow 2mm lugs with a sheet of textured Missiongrip rubber forming the base of the outsole, five deeper 4mm L-shaped lugs on smooth Cloudtec outsole (three on the medial side and two on the lateral side), finally 3mm lugs on three longitudinal sheets of Missiongrip providing for more forefoot grip whilst climbing and finally a semi-circle of L-shaped 4mm lugs at the front of the toebox. 

This is very different to the traditional trail shoe which usually features deeper lugs on the skirting all around and regular height lugs within. Whilst I found the outsole effective on compact and loose gravel, on steep ascents and descents (dry), I did not notice any traction advantage over other trail shoes that I frequent, such as the older Saucony Peregrine 6 and Adidas Adizero XT5.


Much has been covered in the above sections, with all the technology seeming to come into place, but I was let down slightly by the firmer than expected ride. The ride is confident due to the grippy outsole and dialed in fit, and although smooth in transitioning, it is somewhat hampered and dulled by the rigidity of the Speedboard. Perhaps this is a shoe that requires an extensive break in period, and I’ll be sure to provide updates in the near future should it start to provide some give. The ride is overall neither disappointing nor inspiring, with its largest strength manifesting itself during ascents. That said, I also found myself comfortable speeding down steep descents.

Conclusions and Recommendations

The Cloudultra offers quality in craftsmanship and comes in an incredibly aesthetic package.The fit feels race ready but perhaps too snug in volume in all places but the heel cup, but there is slight hope that the elastic in the upper will give slightly over time. The outsole is probably the most impressive part of the shoe from a performance standpoint. Fighting for a place in a shoe category that targets a small proportion of the running community, performance often takes priority when choosing a shoe to run an ultra.

Score 8.20 /10

Ride: 7.5 Fit: 8 Value: 8 Style: 10 Traction: 9 Rock Protection: 9, Weight: 7.5


On Running Cloudultra vs Adidas Adizero XT Boost 5

The XT is old but gold. Featuring a compression garter / bootie upper, the XT like the Cloudultra effectively prevents debris from entering. It has effective lugs and a steeper drop at 10mm. It is softer, far more flexible and is protective enough for an ultra, but maybe perhaps only up to 70-80km. Importantly, it weighs in at almost 45 g / 1.58 oz lighter. Whilst it is a 5 year old model, I would pick the XT Boost for any trail race.

On Running Cloudultra vs Adidas Terrex Agravic Boa

The Agravic Boa is also lighter than the Cloudultra, and features the simple but nifty Boa lacing system which provides fantastic lockdown. However, there is a lack of rock protection with a relatively low stack height of 22mm at the rear and 15mm up front. Its relatively sparse lug pattern means that it is not suited to overly technical nor wet terrain. The Agravic Boa is also voluminous in the toe box, especially when compared to the Cloudultra. The flexible textile upper is also a stark contrast. These two are shoes at the opposite end of the spectrum. I would opt for the Agravic Boa for less technical races 30 km / 19 miles and under, with the On more suited for general trail running with more varied terrain.

On Running Cloudultra vs Saucony Peregrine 6

The Peregrine 6 might be my all time favourite trail shoe. Despite also being a 5 year old model, it weighs in very similarly to the XT Boost 5 mentioned above. The upper and fit are very different to the Cloudultra, which is more dialed in and precise. The additional room in the Peregrine creates room for splay and swelling on long days out but may be an issue for more technical runs. The combination of the PWRTRAC outsole and rock plate provides for a scintillating ride and the midsole with ample cushioning that is more forgiving than the Helion foam. I would pick the Peregrine over the Cloudultra for all distances and conditions.

General Release March 4. Available now at REI in the US HERE

Tested samples were provided at no charge for review purposes. No other compensation was received by RTR or the author for this review from ON . The opinions herein are entirely the author's.
Comments and Questions Welcome Below!
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Paul said...

I'm a bit surprised you are so positive on the outsole. I found this to be the worst part of the shoe. Grip was awful for me, especially with anything wet. Lug pattern is really bad and the outsole material had no traction. Other than that I thought fit, build quality, etc. were all excellent.

Bryan said...

Hi Paul, you might be right! I mentioned that I only tested the shoe in dry conditions and found them to perform well on not-overly technical terrain. The lug pattern is different to convention and found that deeper lugs would have been more appreciated.

Unknown said...

Hi Bryan,

Fist off, thanks for the detailed review.

I seem to find a love/hate relationship with ON shoes in many people. In my view, craftmanship and aesthetic wise ON shoes are top notch. However, when it comes to performance I can see polarized opinions, while on other brands like ASICS, Nike, Adidas, etc, users´ opinions vary, but not that much.

I own a few ON models (Cloudflow, Cloudboom, Cloudflyer, Adventure Peak, and The Roger- this one ain´t a performance shoe), and I understand and share that divergence of opinions.

Very briefly, I find the Cloudflow and Adventure Peak too firm. Yep, they are built to go fast, but that is not at odds with comfort as many other models out there prove.

The Cloudflyer is a very good one, responsive and cushioned, with a non-intrusive support.

The Cloudboom I love it. It´s a plug and play shoe with a plate very easy to run with.

In general, I think ON is on the good path, and they have a great potential to release excellent models, but as of today, they´ve got big room to improve.