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ON Running Cloudultra Review
Written by Chief Editor Matt Klein

It is no surprise that On Running, hailing from Switzerland, would come out with a efficient, high quality ultramarathon shoe. Tested in the Swiss alps, the On Cloudultra is designed to handle any surface over any distance. True to the company, the On Cloudultra features a very high level of attention to detail with some features done a little differently. In typical On fashion, this shoe is unique and will match a distinct set of needs. 

Specifications for the On Cloudultra (per On Running)
Weight: 10.41 oz / 295 g (men's size 9) 8.64 oz / 245 g  (women's size 8)
Stack Height: Not Provided
Drop: 8 mm
Classification: Ultra marathon / Daily Training Trail Shoe


The On Cloudultra is a firmer, all terrain ultra marathon shoe featuring an efficient ride, a gently rockered sole, a wider speedboard and a uniquely adjustable fit system. A full mission grip outsole provides plenty of grip on a variety of surfaces, but isn't so aggressive that it can't handle road. The double layer of Helion foam is firmer, which combined with the speedboard and sidewalls provides subtle natural stability. The upper is thick and protective, but features a unique FlipRelease system that lets you quickly adjust how much room you want in the forefoot. For those wanting a more traditional stack height trail shoe with decent grip, an efficient and naturally stable ride, a durable and versatile outsole and adjustable width in the forefoot, the On Cloudultra may be worth looking into.


The On Cloudultra fits true to size in my normal US men's size 10. The fit is fairly normal to slightly snug from the midfoot to forefoot of the shoe when the FlipRelease is closed. When it opens, both parts open to provide a bit more volume. The heel fits fairly normal to a hair snug. There is a flexible heel counter that wraps around both the medial and lateral side of the heel. The heel collar also fits a bit snug, which seems to narrow at the top. There is a low external heel counter/extended side wall around the heel that I feel some pressure into my rear heel bone while standing and walking when I put the shoes on. This immediately disappears while running and I have never once noticed it even on technical terrain. The upper is thicker in the rear part of the shoe and is reinforced both with mesh and a plastic overlay. In the midfoot and forefoot, there is more open mesh with overlays surrounding the foot. There are two layers to the upper, with a lighter mesh on top and a perforated but thicker mesh underneath. The upper has average breathability up front.

Running through streams does let a little water in, but the upper and feet dry quickly. There is a thick toe guard, reinforced with TPU like the rest of the sidewalls, but it is reinforced on the outer portion of the upper. Inside I had no issues with chaffing and it is very protective. There is no separate tongue as the upper is one piece. The thin laces stay laced, however be careful as making them too tight can cause some extra pressure over the top of the foot (dorsum). This is not a shoe I would wear sockless as there is some stitching between the heel and midfoot portions of the upper. This is a unique upper in that it does keep debris out very well, but is still breathable enough that my feet do not get hot. For those who want a tough, single piece upper with an adjustable volume, this is a good shoe to check out.


The ride of the On Cloudultra is on the firmer end. The ride is protective and smooth when you figure it out, but it is not soft. There is a rocker for efficiency, which combined with the full length and wider Speedboard (plate) makes the Cloudultra feel lighter than the >10 oz weight. This shoe feels great over long and hilly runs. The efficiency helps especially when your legs start to fatigue from climbs or descents. I have had multiple episodes where I have thought my legs were shot from a long decent and the rocker helps them recover for the next one. While there is no official rockplate, the Speedboard does protect the feet against rocks. I have run over a decent amount of rocky terrain, including running at high speeds downhill and did not experience any bruising or irritation going over that terrain. The firmness of the Cloudultra makes it a little clunky during the warm up. I notice it takes me a few minutes to hit my stride in this shoe. There is a sweet spot to really engage both the plate and the rockered sole that when you figure it out, it keeps you rolling. There is toe spring in this shoe and little flexibility. The ride isn't rigid, but those who don't want much flex in the forefoot will like this shoe. The toe off is very smooth and seems to get better as the pace picks up. There is a heel bevel that is biased laterally. When warming up this doesn't roll as well, but when the pace increases a little, the lateral cloud seems to compress more and provide a little more forgiving ride. The stiffness when warming up is also likely due to the stiffer and thicker Speedboard, which engages much better the faster you go. There is an 8mm drop that feels perfect to me. I did not notice the drop at all. The Missiongrip does a great job of providing security on a variety of terrain. I have run on or through gravel, pavement, dirt, streams, sand and mud with decent traction. The traction is good on almost all terrain, however the lugs are not deep enough to handle really wet/slippery ground. During some rare rain here in SoCal I didn't feel as secure when I hit really muddy and slick sections, but all else was fine. The connected lugs decrease the number of rocks that get stuck in the outsole, however I did get a big one still stuck in the guidance line in the rearfoot. Despite some road use, I barely have made a dent in the outsole with 55 miles of total running on these.

The midsole feels similar and the lugs on the outsole are still present, so I expect a ton of miles out of the On Cloudultra. The connected lugs make for a more full length outsole, so I expect this shoe to last far longer than On shoes with the individual lugs.  The Cloudultra can handle road miles, although it is a little firm for longer efforts there.  On technical terrain the On Cloudultra feels fairly good, particularly being closer to the ground than maximalist level trail shoes. However, the ride lends itself more to getting in a rhythm thanks to the rocker and Speedboard, so stopping and going can feel a little awkward. This is a long trail run and ultramarathon shoe, so consistent efforts on mild to moderate terrain feel best.


The On Cloudultra is a neutral trail shoe. However, there are several elements that make the ride naturally stable. There are raised sidewalls, or what could be called a very low external heel counter, that wrap around the heel. There is another larger and higher sidewall in the midfoot on the medial side. This is not a post, but certainly provides some gentle guidance. The final piece of this is a small piece on the lateral forefoot. A very large guidance line runs through the outsole/midsole of the Cloudultra. This starts in the heel, moves into the midfoot and splits in the forefoot. Although this does occasionally catch rocks, this provides some gentle guidance especially as the pace picks up. Finally, the Speedboard, a classic liquid-injected thermoplastic polymer plate in many On shoes, is wider than others from this company. This gives the On Cloudultra more torsional resistance and along with the stiffer sole and rocker, a nice forward guided roll. This is not a shoe that someone with extreme or high stability needs will find enough in, but those with neutral to maybe even moderate stability may be able to enjoy.


     There are three things that stick out to me in the Cloudultra. The first is we are seeing a great prevalence of large lines running through the outsoles of running shoes. These seem to feel good and providing some subtle guidance, but we have no literature/research supporting or disproving the impact of this design. The concept behind this is to create a path of least resistance, through which the foot may gravitate toward. We know from some previous literature we have discussed that the body tends to have its own preferred motion pathway, through which components of a shoe may influence but will certainly not control (Nigg et al., 2017). My questions regarding this component is who best utilizes this, how do you engage it more or less and are different sizes (ie the large version in the Cloudultra) different in effectiveness? All interesting things to think about that are not known.

     The second part is clearly the FlipRelease design. Having adjustable upper volume is important in a long distance racing shoe as foot volume will change over the course of either a race or run. Shorter distance races may not see this, but the fluid intake, tissue damage (edema) and fluid retention (oedema) definitely occur in ultra marathon distance events and distances. This simple trick will go a long way to change volume without having to relace the whole shoe.

     The third part is the Speedboard. We have discussed this a little with previous on shoes, but what I want to highlight is that each plate/Speedboard in On shoes is designed differently. While plates can certainly be used to facilitate forward motion or add some propulsion depending on how much force you put into the shoe, they can also be used to provide guidance. I personally think this is a major factor that is being used by increasingly companies and overlooked by the public. The stiffness in a plate can be used to guide the foot through both loading the plate and its release. However, another major influence may come through the concept of the path of least resistance. The path of motion will go into areas that have a little more give in the plate design. In endurance running, efficiency is very important, ie maintaining the fastest pace for the longest period. The plate is a way to potentially reduce energy loss by maintaining forward momentum. The point here is to not always get stuck in one way of thinking. We are seeing several new components being added to shoes, so always ask yourself what is really happening. Companies are already starting to mess with plate design and we will likely see this continue to evolve in new and unique ways.


Nigg, B. M., Vienneau, J., Smith, A. C., Trudeau, M. B., Mohr, M., & Nigg, S. R. (2017). The preferred movement path paradigm: Influence of running shoes on joint movement. Med Sci Sports Exerc, 49(8), 1641-1648.


The recommendations for the On Cloudultra are focused on the rearmost aspect of the sidewall, heel bevel, the firmness of the midsole and weight. While I have had no trouble other than while walking in the Cloudultras, the rearmost portion of the sidewall/low external heel counter is not necessary. It places a great deal of extra pressure into the lower aspect of the heel bone. I would suggest that On consider splitting that and leaving some open mesh there for the calcaneus (heel bone). The toe spring is done quite well, but I feel there is a little less heel bevel than necessary. Those who land a little farther forward will not notice this, but I tend to land pretty hard on my heel when warming up. This can be a bit jarring, so I might suggest that On moving the heel bevel a bit farther forward. On running shoes are generally on the firmer end. I have yet to experience one that is actually soft, even with the double layer of clouds and the Helion foam (which is also very firm). For me, the firmness works very well. I like firmer shoes and it provides extra natural stability that I personally like. Other people may not like this. Given the move toward maximalist and softer shoes on the market, On may want to see about softening the midsole a little. Personally I don't want them to, but to better reach a larger audience, that may be necessary. Finally, while this shoe feels lighter than 10.4 oz, that is heavy for a shoe with such a large guidance line and so many holes (On Clouds) in the midsole. I challenge On to get this shoe under 10 oz and then you may have a real ultramarathon racer on your hands.


The On Cloudultra is for those who want a very durable shoe with an adjustable upper that can quickly switch between a snug and open forefoot, a firmer, stiffer, rockered ride, a plate for propulsion, natural stability through sidewalls (with an extra piece in the medial midfoot) and a MissionGrip outsole that can handle almost anything you through at it (except really slick mud). Best for long runs and ultramarathon efforts, this is not a max cushion shoe. The ride is firmer, so it works better for softer surfaces, although those who like firm rides will be fine transitioning to ride. It is a very efficient shoe that provides a nice balance between proprioception and protection on the trail. The FlipRelease comes in handy if you want to switch between a snug fit and a more voluminous fit in the front of the shoe. A high quality shoe that will work for a unique runner, the On Cloudultra shows you don't need max cushion to make a great long distance shoe. 



Fit: B+/A- (Bonus points for adjustable forefoot/midfoot. Heel is snug with flexible heel counter. External heel counter/sidewalls cause some pressure on calcaneus while walking, but disappears while running. Slightly too snug with FlipRelease off however, so most will probably leave it loose like me.)
Performance: B+ (A little firm on the warm up, but a very efficient ride that feels a little lighter than the listed weight. Good traction, but lugs not deep enough for muddy terrain. Heel bevel could be increased in size as you have to warm up to find the sweet spot of the ride. ) 
Stability: A- (Several natural stability elements in this neutral trail shoe. Very supportive over long distances thanks to wide speedboard, strategically placed sidewalls and guidance line) 
DPT/Footwear Science: A- (Adjustable forefoot for longer distances is great. Use of speedboard and sidewalls, which should be emphasized way more, are done very well. Wish heel bevel was a bit more to take the edge off the ride on road) 
Personal:  B+ (Really like this shoe. Wish it was a bit lighter. Been my go to trail training shoe since I got it) 
Overall: B+ (Really well done, efficient ultramarathon shoe that keeps your feet fresh without being high off the ground. Very good natural stability without being overbearing and very protective) 


Interested in purchasing the On Cloudultra?
Check out Running Warehouse here.
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Shop gear we enjoy:
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New Balance Rebel V2
Fast, fun, and surprisingly versatile

Rabbit Running Clothes: Incredibly soft, high quality clothing for your next run
Feetures Socks: Massively grippy socks that will make you feel more one with the shoe
Trigger Point Foam Roller: Help get those knots out post-run and feel better for tomorrow
Coros Pace 2 Watch: Excellent watch for various running goals and a massive battery life
Theragun Massager: This small version is great on the go for working tired legs


More from On Running
On Cloudflow (V2) - The brand's lightweight trainer. Nimble and reliable
On Cloudswift 2.0 - A big update to their daily trainer, featuring sustainable materials
On Cloudboom - On's first attempt at carbon plated racing. Aggressive fun
On Cloudventure Peak - The brand's lightweight, nimble trail runner, with an extra sticky outsole
On Cloudflyer - On's light stability trainer

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Thanks for reading!


Dr. Matthew Klein is a 140 lb male with notable PRs of 14:45 for 5k and 2:32:44 for the full marathon.  He typically runs 70-100 miles per week and trains at a variety of paces from 8min per mile recovery runs to 4:40 per mile 1k repeats.  He prefers firmer and responsive shoes with snug heels and medium to wide toe boxes.  He is particular to less cushioned shoes and close to the ground shoes, but can handle a little cushion when he gets beat up. IG handle @kleinrunsdpt

Editor's Note: As always, the views presented on this website belong to myself or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your local running physical therapist. If you are in the Los Angeles area, I am currently taking clients for running evaluations.

Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Fellow of the American Academy of Orthopedic Manual Physical Therapists

Nathan Brown PT DPT MS
Doctor of Physical Therapy 
Masters in Anatomy and Clinical Health Science
Movement Performance Institute Certified in Advanced Functional Biomechanics 

David Salas PT DPT CSCS
Doctor of Physical Therapy
Certified Strength and Conditioning Specialist

Bach Pham MS
Marketing and Social Media Manager
Master of Arts in Cultural Anthropology

***Disclaimer: These shoes were provided free of charge in exchange for a review.  We thank the  people at On Running for sending us a pair.  This in no way affected the honesty of this review. We systematically put each type of shoe through certain runs prior to review. For trainers and performance trainers, we take them on daily runs, workouts, recovery runs and a long run prior to review (often accumulating anywhere from 20-50 miles in the process). For racing flats we ensure that we have completed intervals, a tempo or steady state run run as well as a warm up and cool down in each pair prior to review. This systematic process is to ensure that we have experience with each shoe in a large variety of conditions to provide expansive and thorough reviews for the public and for companies. Our views are based on our extensive history in the footwear industry and years testing and developing footwear. If you are a footwear rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.

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