We spent 8.1 hours reading reviews from experts and users. In summary, this is what runners think:

8 reasons to buy

  • Most users admired the overall structure of the Asics Gel Nimbus 21 because it is durable.
  • A few wearers noted that the cushioning of the Nimbus 21 feels lighter and more responsive compared to its predecessor.
  • The shoe has a great fit, according to some reviews.
  • A couple of users lauded the nice looking design of the shoe.
  • Several buyers mentioned that the toe-box fits wider than expected.
  • The Asics Gel Nimbus 21 has a breathable upper, said some comments.
  • According to some runners, the shoe is very comfortable; the feel is consistent even on long distance runs.
  • This running shoe offers good heel support, based on a few user reviews.

1 reasons not to buy

  • It is very expensive compared to other road running shoes.

Bottom line

Majority of the users were welcoming and happy about the Asics Gel Nimbus 21. The shoe obtained a winning spot to many consumers because of its breathability, responsive cushioning, and impressive fit. Though the shoe is expensive, its comfort level and durability were more significant. Overall, the Nimbus 21 is indeed a successful update.



A top rated Road running shoe
A top rated Asics running shoe
Top 1% most popular running shoes
Better rated than the previous version Asics Gel Nimbus 20

Expert Reviews

85 / 100 based on 19 expert reviews

  • 90 / 100 |

    First look and impressions - The Asics Gel-Nimbus 21

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    This 21st iteration of Asics’ premium neutral cushioned shoe comes loaded with features, including, but not limited to:

    • Rear and fore-foot Gel cushioning for impact absorption
    • Two variants of FlyteFoam – Propel for elastomer compound bounce and Lyte with organic nano fibres for cushioning
    • Trussic system integrating Guidance technology for improved gait efficiency
    • SPeVA 45 lasting – Full-length SPeVA foam lasting for soft feel, rebound, and durability
    • Ortholite X-40 sockliner for higher rebound and better moisture management


    Asics calls the shoe “re-engineered” and this I suppose is merited given the use of two different types of FlyteFoam (Lyte and Propel: first time in Nimbus although already introduced earlier this year to Gel-Kayano 25 and Gel-Cumulus 20) in addition to a new, wider last and lateral full-contact outsole.


    Unboxing the new Asics Gel Nimbus 21

    First look

    The upper features two-layered jacquard material, new for Gel-Nimbus but again seen first on Gel-Kayano 25. Use of premium material throughout is evident and the shoe is immediately comfortable. 


    Two-layered jacquard up close


    With toe stack at 13mm and heel stack at 23mm, the shoe comes with 10mm drop which Asics considers so optimal to running that they’ve given it a name – HG10MM.

    At 310 grams stated weight (my US 10.5 comes in at 336 grams) Gel-Nimbus 25 adds 5 grams to the previous iteration.

    The look of my Black/Classic Red colorway is best described as “retro.” Despite laden with the latest technology and innovation, the shoe manages to retain that familiarity. I’m sure long-time fans would not disagree.

    A feature described on the website refers to use of reflective material in upper to enhance night time visibility but, try as I may, I other than the reflective patches on the heel, I didn’t notice anything else.


    Retro: love it or not. I’m not yet sure which!


    I have to think that a good chunk of that additional weight versus version 20 is due to the outsole. The outsole is indeed full-length, and visibly chunky.

    Both the Guidance Line and the Trussic system, interestingly, are subtle, at least over previous versions. “Lateral full-contact outsole” I take to mean basically a wider foot-print.


    Barely-there Guidance Line and Trussic system and wide foot-print


    There is a modest external heel counter, but a much more substantial one within.

    The use of Ortholite collar sponge should go a long way towards comfort, unlike in, say, Gel-Cumulus 20 where I found the collar too intrusive.


    External heel counter, Gel, FlyteFoam Propel (white) and FlyteFoam Lyte (black)


    First impressions

    The shoes are immediately comfortable. While the new supposedly wider last is not noticeably wider than, say, Gel-Kayano 25, it is a much better fit than Gel-Cumulus 20, which I found too tight.

    It is a good fit without being too roomy or loose, perhaps attributable to the forgiving but supportive nature of jacquard mesh. For Gel-Cumulus 21 I went with my usual US 10.5 (UK 9.5, EUR 44.5), which worked well for Gel-Kayano 25 but proved perhaps ½ size small for Gel-Cumulus 20.

    Over 3 runs totaling 16 miles, I observe the following:

    • The ride is plush and smooth, especially at slower speeds
    • Cushioning is on the softer side (compared, say, to Gel-Cumulus 20) but not too soft and still manages to be responsive
    • Forefoot cushioning is particularly noticeable (in a nice way)
    • Outsole traction in wet surface is excellent and reassuring
    • The wider foot-print feels a bit cumbersome and particularly noticeable when cornering
    • Upper remains comfortable and supportive throughout


    While a full review in due course after much more extensive testing will no doubt flesh out above points (perhaps even overturn them?) initial impressions are that Gel-Nimbus 21 is well suited for the long slow distance runs, for daily training, and for marathon distance racing.

    I believe the additional stability offered by wider full-contact outsole favours the heavier runner (and at 174cm and 71kgs I don’t believe I am one) who do not require support to the extent available through Gel-Kayano 25.

    I like the use of high-quality materials and resulting comfort and plushness but I’m undecided regarding styling and not a fan of the wider outsole. Watch this space for a full review!

  • 78 / 100 |

    My first impression of the ASICS Gel Nimbus 21

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    I’m a tall, medium build, fore-midfoot striker and I train mostly in barefoot/minimal shoes. But I’ll try anything once!

    Getting the chance to test out the newest addition to the famed Nimbus line was a chance I couldn't pass up! I love the idea of the dual-foam midsole technology. One to absorb the shock and one to put a spring in your step.

    Let's see how these every day running shoes are on first impressions.


    Tech Specs

    • Weight - 375g (UK11, US12) as weighed by me!
    • AHAR®  outsole - Acronym for ASICS High Abrasion Rubber. Placed in critical areas of the outsole for exceptional durability.
    • Flytefoam® Proper technology - ASICS energetic foam formulation that provides supreme bounce thanks to a unique elastomer compound.
    • Reflectivity - Contains reflective materials designed to enhance visibility during low light hours.
    • Flytefoam Lyte Technology - Asics lightest weight midsole formulation that provides continuous cushion thanks to organic nanofibers.
    • Heel clutching system™ technology - Exoskeletal heel counter provides improved support and creates improved heel fitting environment.
    • Rearfoot and forefoot gel® technology cushioning system - Attenuates shock during impact and toe-off phases, and allows movement in multiple planes as the foot transitions through the gait cycle.
    • I.G.S® (Impact Guide System) technology -ASICS design philosophy that employs linked componentry to enhance the foot's natural gait from heel strike to toe-off.
    • Guidance Trussic System™ Technology - This Trusstic System® Technology integrates Guidance Line® construction for enhanced gait efficiency while providing midfoot structural integrity.
    • Guidance line ® midsole technology - Vertical flex groove decouples the tooling along the line of progression for enhanced gait efficiency.
    • Spevafoam™ 45 Lasting - Employs 45-degree full-length SpevaFoam™ 45 lasting material for a soft platform feel and improved comfort.
    • Ortholite® X-40 Sockliner - This premium sockliner features higher rebound properties while providing excellent moisture management and a high-level of breathability (Ortholite is a registered trademark of ATP Manufacturing LLC.)

    Design overview

    Looks-wise I think these are horrible. They’re like something straight out of the ’90s! I don’t really have much else to say really, I’m just not a fan of the styling here.

    With a heel 23mm high and a forefoot 13mm high there is a relatively standard heel to toe drop with the Nimbus. They feel really high up compared to other shoes of a similar sole height, I’m not entirely sure why that is but I definitely notice the heel height on these more than usual. Initially, this worried me because the last thing I want is to feel as though I’m wearing high heels whilst I’m running.


    The upper on the Nimbus 21 is a two-layer jacquard mesh design. It’s meant to be flexible but I really don’t think it’s got much give in it. I am much more a fan of knit uppers since my testing of the Nike Epic React Flyknit.



    The upper on the Nimbus is very similar to that of the Dynaflyte and that too is a little unforgiving.


    The laces on these road shoes feel quite cheap but they are very soft and seem to grip quite well, though certainly not the best I’ve come across.


    Heel counter

    The heel counter on these shoes is very hard, heavy and stiff. It’s very close to the style of the one of the Dynaflyte and I have to say as much as I dislike it for its lack of flexibility and the weight it adds it really works well to hold my foot in place.



    What can I say about this thing? I mean, it’s all just too much. I know that every shoe can’t always be minimal but I really don’t see the need for some to be so extreme.

    Yes, it’s soft and comfortable but with them on I couldn’t honestly say the massive collar makes them any more comfortable than my Vibram FiveFingers that have no padding at all!



    There’s nothing special going on here tongue-wise. It’s a bit padded but not too much. I’ve only done one run in these so far but nothing found its way in past it, so I suppose that’s a mini victory.


    There are reflective strips on the sides of the Nimbus.

    Anyone who’s read any of my reviews before will know that I don’t see the point in reflective strips. Thankfully although there are a lot of them on these road shoes they don’t work very well! Hah!



    Now usually I don’t really like running shoes with more than a 4mm heel to toe drop but I really, really like the sole on the Nimbus. ASICS have done a great job on this shoe.

    The Nimbus has a dual foam midsole that consists of a soft, light foam that is predominantly at the heel for shock absorption and a more responsive, rubbery foam that is mostly at the forefoot.



    I love this idea. It means that this shoe works for both heel strikers and forefoot strikers. Being the latter, I can only really attest to how well they work for people who land on their forefoot.

    I love how responsive these feel. They have just enough cushioning that they absorb the shock of impact but they also have great energy return so I didn’t once feel as though they were killing my momentum.

    Another plus point to these road shoes is that because of how responsive they are, they actually feel lighter to run in than the Dynaflyte do. Even though they’re almost 100g heavier and aren’t even designed to be fast like the Dynaflyte is. Another win for the Nimbus.

    I almost forgot to add that there’s some gel in the sole somewhere too. I’m not sure what it’s meant to do or what it does do but it’s there.


    The arch on these comfortable road runners isn’t very noticeable. I really like this about the Nimbus 21.

    I’m not a fan of intrusive aches digging into the soles of my feet. But because my feet can act a bit more naturally this actually adds support. My feet are able to adjust better to the ground.



    The heel also adds to the support value here. It really locks my foot in place with little to no slippage whilst running.

    There is a plastic ‘trusstic’ on the sole that is meant to add some support. So far I can’t confirm nor deny that it does anything positive. I have a bit of a hunch that it could just be more of a novelty selling point than any actual use.


    Considering the thickness of the sole on the Nimbus the toe feels reasonably flexible.

    What’s interesting is that on the Dynaflyte if I flex the shoe in hand it feels more flexible than the Nimbus does. But with them on the Nimbus feels much more supple. I think it might have something to do with the Flytefoam Propel part of the sole on the Nimbus.


    The tread on these shoes is decent. It’s aggressive enough that it’s suitable for a lot of different surfaces. It can handle a little trail but nothing crazy.

    Because the sole is so soft it’s great over hard ground and even some rocky terrain. I definitely wouldn’t advise running in mud, but I think that kinda goes without saying (even though I just said it).



    The grip is great! I mean really really good! Once I got passed the new sole rubber slippy-ness stage (you know what I’m talking about), they really impressed me.

    The rubber is incredibly soft, possibly too soft but time will tell. I have worn the sole down quite a lot already and I’ve only done one 7.5 mile run in these so far. 

    Fit & comfort

    Despite Asics saying that the Nimbus run true to size but they definitely don’t. My toes touch at the end of the shoes. I definitely could have done with a half a size or even a size bigger.

    Toe box

    Again ASICS have it all wrong. They say the Nimbus 21 has more toe room than the Nimbus 20 did to allow room for toes to splay.



    I can categorically state that my feet have nowhere near enough room for my toes to do anything. I have no idea how tight the Nimbus 20 must have been!! It’s a real shame and along with the sizing issue is the one major flaw to these shoes.


    The heel fits so snug. It’s a tight fit but I really love that about these shoes. It’s also very comfortable. Yes, it’s weighty and stiff but heck, my feet ain’t complaining!


    The highlight of these shoes so far! I am really impressed. On my 7.5 mile run, I did 4 miles at a reasonable pace and the rest at a steadier pace. I threw in some groomed trail as well as some wet sand and plenty of ups and downs.

    The Nimbus was brilliant at both paces and over each surface. From the moment I set off running, I was surprised at how springy these shoes feel. Having just finished reviewing the Dynaflyte I can’t believe how much faster these are than they were!!

    I’m actually looking forward to smashing a lot more miles in these, despite the lack of toe room! I think that says a lot!


    As I’m sure you can tell the Nimbus 21 has made a serious first impression!

    I wasn’t sure how well I’d get on with these but I’m so glad I decided to take on the challenge! The sole technology is brilliant! I need more Flytefoam Propel in my life! It’s almost as good as Nikes React foam and that stuff is basically too good!

    I’m looking forward to seeing how well these get on over the next 42.5 miles before I write my final thoughts on them.

  • 92 / 100 | Ashraf Alam | Level 1 expert

    It's a racehorse. It is a super fast shoe. It's really light. The best thing about this shoe is the upper mesh. It is really breathable.

  • 80 / 100 | DirtyOldSneakers | Level 1 expert

    It's a good shoe. But like I said, performance, design and fit, I'm gonna go with the 20.

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Jens Jakob Andersen
Jens Jakob Andersen

Jens Jakob is a fan of short distances with a 5K PR at 15:58 minutes. Based on 35 million race results, he's among the fastest 0.2% runners. Jens Jakob previously owned a running store, when he was also a competitive runner. His work is regularly featured in The New York Times, Washington Post, BBC and the likes as well as peer-reviewed journals. Finally, he has been a guest on +30 podcasts on running.