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On Cloudflow Review 2021: The Second Generation Cloudflow is Here!

The On Cloudflow is back with a new design that gives these popular running shoes a very different feel to the original Cloudflow (reviewed here). This in-depth On Cloudflow review focuses on the key features of these running shoes, how well they perform while running in them, and as always how well they rank against other On running shoes in our Best On Running Shoe Reviews [Ultimate Buyer’s Guide]. While the new On Cloudflow looks similar to the original, it’s a very different beast. It feels much more responsive, flexible and cushioned (thanks to the new Helion outsole) while still maintaining the high-performance of the original Cloudflow. The On Cloudflow 2 is very much a 5k, 10k and half-marathon running shoe for fast training sessions and races, but those who enjoy running marathons in a more minimal running shoe will also love these. Keep on reading to find out why I have awarded these running shoes an Editor’s choice award.

If you’re after a highly-cushioned On running shoe for marathons or road ultramarathons, have a read of my Cloudstratus, Cloudace, and Cloud X reviews after this one.

Hopefully, this On Cloudflow review answers all the questions that you may have about the latest model. If not though, please feel free to ask me anything in the comments section down below, I will usually respond within a few hours.

On Cloudflow Sizing and Fit

On Cloudflow review 2019 2020 trail and kale wm 2

If you’re familiar with On running shoes then you probably know they generally feel comfortable right out the box, the Cloudflow is no exception. Much of the comfort comes from the cozy inner layer of the upper. The internal sock (pictured below) that is attached to the sides of the tongue also adds to the overall comfort as it helps the upper wrap-around and conform to your feet. This reduces the chances of any chaffing and blisters too.

On Cloudflow review - Inner sock
Inner sock

The shoe fits true to size relative to other On shoes and other popular brands like Nike, Adidas, and Brooks Running for example, so there’s no need to size up or down, go with the size that you’re used to.

The On Cloudflow Upper Construction

On Cloudflow review breathable and stretchy upper
breathable and stretchy upper

The upper is very breathable with zone ventilation in the right places to keep your feet cool while running hard and fast. There’s also some stretch in the upper too, which helps keep your feet comfortable as they expand in the heat of your run. I really like the addition of the elastic strap on the tongue which is for securing your laces one tied up (see image below).

On Cloudflow review 2019 2020 trail and kale wm 8

This is very useful because in the past, anyone with average to slim feet would have had to deal with excess laces flapping around during a run unless you tied a double knot.

The materials get thicker and more cushioned towards the rear for additional heel and ankle support (see image below).

On Cloudflow review 2019 2020 trail and kale wm 10

Looking at the image above you’ll notice a solid plastic strip that acts as a heel cage, designed to lock your heel in place and reduce lateral foot roll. This gives a really stable yet responsive feel while running fast, particularly when you need to dodge people in crowded places.

Roger Federer wearing the On Cloudflow Video

If you didn’t know already, Roger Federer has joined the team at On Running in an effort to collaborate and help shape the future of research and development of the Swiss running brand.

Roger will use his unique experience to help take product development, marketing, and fan experiences to new levels. This is very exciting news for the direction of the brand. How and why did they become partners? Roger was spotted wearing On shoes around the world, by the On team, and so they reached out, not in the traditional sponsored athlete sense, but more of an entrepreneurial collaboration between them both. I guess Switzerland is a relatively small place and it makes sense for two such powerhouses in design and sport to collaborate at some point!

The Helion midsole makes it to the On Cloudflow 2

On Cloudflow review - Cloudflow 2 Helion Midsole
Cloudflow 2 Helion Midsole

The second-generation of the podium-topping Cloudflow shoe loved by many elite athletes now has the latest cushioning tech, Helion. Refined with input from world-class triathlon and running athletes the new Helion superfoam midsole provides a really smooth ride, soft landings and very explosive take-offs. With the new Cloudflow 2, you can expect more kick, more speed, and more comfort over shorter runs. On does say that they recommend this shoe for Marathon running too, but in my opinion, it is too minimal and your feet will start to suffer after a few hours of running on the roads. If you are used to running long distances in lightweight minimal shoes though, these are definitely for you.

On’s Speedboard combined with this Helion midsole make the Cloudflow 2 a very cushioned shoe that will inevitably allow you to run faster than you may be used to, solely due to the fact that your feet will feet comfortable and as such you’ll want to push harder.

On Cloudflow review - advanced traction pattern offers better grip on slick wet surfaces
advanced traction pattern offers better grip on slick wet surfaces

The Cloudflow outsole rubber compound and tread formation have been updated too. The tread is now in an advanced traction pattern that offers much better grip on wet roads. Something that is required on some city sidewalks.

Cloudflow weight and drop

The On Cloudflow weighs 235g (8.29oz), which is very lightweight and there’s a drop of 6mm from heel to toe which actually feels closer to 4mm, I don’t know why but it just does. Helen and I both thought the same.


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The On Cloudflow 2 has neutral running stability which means that they’ll feel good on most people but there is definitely a subtle amount of arch support/cushioning in there, which feels more pronounced than other On’s but I like how it hugs your feet none the less.

On Cloudflow review 2019 2020 trail and kale wm 6
medium width toe box

Toe Box

The toe box is medium/normal width and feels airy due to the very breathable upper material.

On Cloudflow review 2019 2020 trail and kale lrg 1
On Cloudflow 2 Review
Design & Function
Very comfortable on runs up to half-marathon. Marathon runners who enjoy minimal shoes will love these for Marathons too.
Comfortable out of the box
Very lightweight (8.29oz / 235g)
Elastic strap on the tongue for stowing laces
Very breathable
A little minimal in the midsole for long distance running
Overall Score

Shop Men’s   Shop Women’s


In summary, the On Cloudflow is one of the best lightweight running shoes for running races of distances between 5km and the half-marathon. And I have ranked them as the number 1 best On running shoes for road running. Marathon runners who enjoy minimal running shoes will have a lot of fun in these responsive shoes too. The toe box is airy and of a normal width and the midsole has the enjoyable Helion foam that responds well to fast running on hard surfaces.

The upper is really breathable and I love how the material stretches and conforms to your feet while you run. The upper is a big improvement over the original Cloudflow. These are currently my go-to running shoes for fast-paced speedwork.

At $139.99 the On Cloudflow is very well priced for such a durable and high-performance racing shoe.

Jump over to our Best On Running Shoes Ranked and Reviewed buyers guide to find out how well the Cloudflow 2 ranks against other On running shoes, HINT – They’re rocking it!

Still not sure which On Running Shoes to buy?

Visit our Best On Running Shoes Guide for an ordered list of the top ON shoes for road and trail running, each with links to our On Shoe reviews. Designed to make your buying decisions clearer.

Best On Running Shoes Reviewed

On Cloudflow Review 2021: The Second Generation Cloudflow is Here! 1 - Trail and Kale | Trail Running & AdventureThe On Running Brand

Founded in Zurich, Switzerland from a revolutionary idea, a Swiss running shoe has evolved that is still amazing the sporting scene. The On provides a new running sensation and one that puts fun firmly centre-stage.

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On Cloudflow Review 2021: The Second Generation Cloudflow is Here! 2 - Trail and Kale | Trail Running & Adventure
On Cloudflow Review 2021: The Second Generation Cloudflow is Here! 2 - Trail and Kale | Trail Running & Adventure
On Cloudflow Review 2021: The Second Generation Cloudflow is Here! 2 - Trail and Kale | Trail Running & Adventure
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  1. Living in Monterey county, ca. We have a lot of mixed running. Road
    Running to get dirt trails. Have you had experience with mixed surfaces. The trials are mostly packed dirt, single track(mountain bike trails) to some looser sandy trails. I just bought these and would love
    To wear them on any type of run. Thoughts? Thank you

    • Hey Justin, what a wonderful part of the world Monterey is! 🙂 the Cloudflow is very much a road running shoe but i guess you could wear them on buffed, hard-packed, and dry trails. The closest On trail running shoes to the Cloudflow would be the Cloudventure Peak. They will definitely be better suited and actually handle road surfaces pretty well too! Hope that helps a little?


  2. I had the first gen Cloudflow which I used mainly for road. However I also did a 100km trail in them. It was dry trail mostly dirt with few small stones here and there. Worth noting I had changed the insoles with some gel to provide extra cushioning. They were brilliant.

  3. Hi! I am the “marathon runner who enjoys minimalist shoes”. I’ve been running in Vibrams 7 years and have finally hung them up and decided to wear real shoes (after years of pressuring from friends and family). That being said, I am looking for every day trainers that are minimalist. Do you think that the cloudflows could work for that use rather than just for speed work? Thank you! 🙂


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On Cloudflow Review 2021: The Second Generation Cloudflow is Here! 5 - Trail and Kale | Trail Running & Adventure