ASICS GEL Nimbus 21 Review: The N Formula Deftly Tuned

Article by Hope Wilkes, Jeff Beck and Sam Winebaum

ASICS GEL-Nimbus 21 ($150)

Introduction

Sam: The Nimbus 21 continues, and deftly tunes, the long standing Nimbus formula of bomb proof snug upper, great under foot stability, a densely protective and cushioned ride, and long durability in an every day moderate pace trainer.  My last Nimbus was the 19 and it was the shoe I reached for this year when I had a bout of Plantar’s for all of the reasons above but not for plush, comfortable, or fast. Never an inspiring or even that comfortable a shoe, the 19 got the job done but without to much excitement. The product description for the 21 includes “supreme”, “ultimate” “plush” and other such descriptors. The 21 does not fundamentally change the formula of supremely supportive, cushioned and protective but those attributes are softened a touch, relaxed and made somewhat liviler on the run. as well Basically, the Nimbus is no longer a chore to run. I expect Nimbus fans will not be disappointed.

The changes include:

• The upper is now a fine soft double jacquard mesh nicely supported by subtle overlays. The straight jacket approach of the 19 with its dense tight mesh is gone. We now have some give and room in the toe box.
• The complex midsole with its front and back GEL inserts now substitutes an underfoot  layer of bouncier Flytefoam Propel for Flytefoam, and Flytefoam Lyte for the Flytefoam of the 20.
• The plastic under midfoot Trussic plate is reduced now only appearing on the medial side.
• The outsole sees significant changes. Gone is the vast unbroken expanse of firm hard rubber upfront. We now have a nicely segmented softer blown rubber which combined with the Propel really softens and moves things along more smoothly and with less shock.
• And my men’s size 8.5 is now 0.4 oz /11.g  lighter than the 19 at 10.44 oz / 296 g and a touch lighter than 20 helping place the weight in the realm of the reasonable for a heavy duty premium trainer.

Hope: I try to not bore normal folks with running shoe talk, but enough has seeped out that I am the go-to shoe recommender for friends, family, and colleagues. Not everybody has the same needs and preferences as I do, so I strive to be informed about a wide range of shoes. I requested the Nimbus 21 expecting to not like it. I didn’t like it. But now my opinion of the shoe is fact-based. Even though I’m not a fan of the shoe, I grant that there are very few flaws in the execution of the design. It just so happens that the design is not my preference, but it might be yours. I fully expect to get smoked at a 10k this summer by some sneaky-fast dude in the Nimbus 21 who’s been running since before I was born. This shoe is beloved by many and I would never say that those people are wrong. In my review I’ll endeavor to approach the shoe more from the perspective of “does it do what it’s meant to do?” and less from the perspective of “did it wow me?”

PROS

Comfort, quality materials/construction

Highly protective and stable with some new liveliness on the run from midsole and outsole changes

CONS

Weight

Complex underfoot feel

Concerns about early forefoot rubber wear

Stats

Weight: men's size 9: 10.9oz. / 310 grams,  women's size 8: 9.6 oz / 272 g

Samples: US M8.5  10.44 oz /296 g 0.4 oz, US M10.5 11.6 oz/330g

Stack Height: (including 5mm sock liner)

men’s 28mm heel / 18 mm forefoot, 10 mm drop

Women’s 30mm heel* / 17 mm forefoot, 13mm drop

*ASICS adds 3 mm of heel stack to help relieve achilles tension in the women’s model

$150. Available now.

Tester Profiles

Jeff Beck is the token slow runner of the RTR lineup. As a middle-of-the-pack runner, his viewpoints on shoe and gear can differ from those who routinely finish marathons in three hours or less. Jeff runs 30 miles per week, both roads and desert trails, in North Phoenix, Arizona. He has a PR's of 4:07 marathon and 23:39  5K, both he is working to demolish with help from his coach and fellow RTR tester Dave Ames.

Sam is the Editor and Founder of Road Trail Run. He is 61 with a recent 3:40 Boston qualifier. He runs halves in the 1:35-1:41 range and trains 30-40 miles per week mostly at moderate paces in the 9 minute range.

Hope is in her 20’s and after several ultras is now more on the road. She has a marathon PR of 3:47. She trains about 50 miles per week with many of her runs in the (broad) 8:00-10:00/mile range. She is happy to hit 7:30 miles on tempo days.

First Impressions and Fit

Jeff: The Nimbus 21 is the first shoe I've reviewed sight unseen. Every other shoe I have reviewed there's been some sort of sneak peek, but not this time around. Right away I was impressed by the midsole, and how much of it there was, while feeling like the upper is a little bit behind the curve design-wise. I have become a toe box snob this year, and at first glance, I could tell there wasn't going to be any issues.

Sam:The fit was true to size with a far softer fit than the rough mesh of 19 with more toe overhead room. The achilles and rear heel  collar is lower and far more comfortable than the 19. ASICS still calls the external heel exo-skeleton the “ Heel Clutching System”  but now it far more reasonable in support when combined with the lower collars, previously being way over done. I also note a less snug medial arch fit, the 19 was very snug there due to the dense upper.

As far as appearances my pair follows the current very dark and white trend. I find the white Propel layer a particularly striking visual and functional design highlight. The overall craftmanship is impeccable and robust. Jeff’s blue with lime green really highlights the classic Tiger logo overlays. My first real run shoes in the 1970’s were Tiger Marathons and were light blue with a prominent white Tiger overlay logo.

Hope: I received an all-black pair. Nothing fancy, but they were clearly well put together. It has the classic styling I’ve come to expect from this brand. Generally, I have a hard time distinguishing between the various Asics performance running shoes except up close and the Nimbus 21 is no exception. The fit is roomy without being sloppy. The external heel counter does its job well. I really appreciated the roomy toe box. There’s enough height in the toe box and the mesh is accommodating enough that I can flex my toes easily – always a marker of a comfortable shoe.

Upper

Sam: The upper is a space double layer jacquard mesh as many 2018-2019 shoes are going to. Jacquard construction allows a combination of soft comfort and structure by essentially knitting from both sides differentially  The upper is very comfortable with plenty of toe box room and pressure free midfoot volume, both in sharp contrast to what I found was a very restrictive upper in the Nimbus 19.

While clearly toned down and lowered, I still think the rear of the shoe is over built and over supportive for a neutral shoe. The exoskeleton Heel Clutching System seems to me more appropriate for a support or stability shoe. This said the heel hold is “supremely” secure. I think runners in need of some pronation control of the less extreme variety when upper and midsole Trussic plastic are taken into account can run this shoe and avoid the yet heavier Kayano.

Adding to the premium feel and performance ASICS builds in an Ortholite heel collar sponge and a molded EVA sockliner.  The Nimbus 21 will be available in standard width, 2E, and 4E.

Jeff: ASICS has a certain aesthetic they are going for, and they definitely hit it with the Nimbus 21. If you are familiar with running shoes, you'll be able to identify its ASICS heritage from forty yards away. There are a number of more modern touches to this upper, and the result is a very comfortable, if not necessarily stylish shoe.

The external plastic heel counter has large gaps, allowing your heel to settle in, and it didn't feel restrictive in the least. The padded collar held my foot very well, and the toe box, while not being an Altra or Topo level of wide, still had plenty of room in the standard D width.

Hope: Jeff’s impressions basically match mine here. The materials are all very soft and plush. In my experience, Asics has always been the leader in step-in comfort. The laces are so soft I might even go so far as to call them huggable which is weird, but let’s go with it. I didn’t take the Nimbus on any super long runs, but I think it’s fair to say that top-down lace pressure wouldn’t be a problem.

Midsole

Sam: While forefoot and heel GEL inserts remain in the picture, the rest of the midsole is modernized with a soft and bouncy layer of Flytefoam Propel underfoot and substitution of Flytefoam Lyte for Flytefoam below that. The effect is of a bouncier less dense ride than the lumbering if responsive and firm 19. The 20 had Flytefoam but no Flytefoam Propel and although I did not run the 20, from other ASICS I have tested I know Flytefoam Lyte was more responsive than Flytefoam and Propel is yet livelier and bouncy in feel.

The picture above of Jeff’s pair illustrates the cushioning elements of the midsole very well with ASICS using different colors to highlight each. Flytefoam Propel is the white layer, the green lateral heel piece is the rear GEL insert (front being embedded), with the blue layer Flytefoam Lyte.

And the view from the medial side.

While between outsole and midsole it is worth mentioning here that the Trussic PEBA element (same material as in some exotic newer midsoles but here molded into a rigid very light piece) right under midfoot is now thankfully relegated to only the medial side for some pronation control with the lateral side filled with blown rubber outsole. I wish ASICS had kept the narrower midfoot geometry of the 19 though which would have potentially aided transitions yet further.

The combination of GEL, Propel, Lyte, Trussic plate here is effective but I did sense a complex feel of different densities and characteristics of each component of cushioning, not exactly smooth and seamless for sure but more mechanical and  purposeful, more like a well designed machine than a slab of simple foam, all of piece. This is not a super soft midsole for sure but it is softer than previous and bouncier.

Unlike the 19 with its firm Flytefoam as we now have that softer Propel layer. I for sure felt the pleasing impact reducing effect of the heel GEL far more than in the 19.   

Jeff: ASICS is using its new Flytefoam Lyte with Propel in the Nimbus 21, and the result is a relatively firm and responsive shoe considering the stack height and weight. In my previous life I was a caddie at a golf course, and for years spent every day running around the course in a pair of Nimbus, ranging from the Nimbus 8 to the Nimbus 12, and the cushioning of those earlier shoes wasn't nearly the same level of responsive. I could come up with a few dozen words to describe the 21 until I got to the word plush, and that used has been and still is a Nimbus major identifier. That said, I think the firmer and still well-cushioned midsole is the better way to go, and this midsole has a similar feel to one of my favorite shoes of the year, the New Balance 1080v9. Like the 1080, I never felt like I was sinking into this shoe, but the Nimbus does not have nearly the same level of flexibility - likely a result of ASICS including their plastic Trusstic system. If you are a a moderate to severe overpronator including Trussic may be a game changer for you, but neutral runners will likely see it as a negative.

Hope: I didn’t notice the midsole. In the sense that nothing got in my way, that’s a compliment. In the sense that I wasn’t delighted or disappointed by the midsole’s contribution to the Nimbus 21, it’s just a neutral statement. If the Gel does anything, I can’t tell. To remain a leader in the performance running shoe category, Asics needs to have more memorable, impactful tech in its shoes. The storied Nimbus 21 might just not be the model where they’re trying to make waves. I’d be willing to bet that if you liked the Nimbus 20 midsole, the Nimbus 21 midsole will work for you. Personally, I would have preferred to have the firmer FlyteFoam Lyte layer that’s underneath the heel and midfoot extend up to the to the forefoot as well.

Outsole

Jeff: The Nimbus 21 outsole is largely covered in durable rubber, the blue piece at mid foot being the PEBA Trussic plastic support. There are a few small spots of exposed midsole, but the rubber extends far enough out that the midsole won't see much wear until the rubber has worn away hundreds of miles into its life. There are gaps in the rubber up front, allowing the shoe to flex some as you run in it, and the shoe has the ASICS classic decoupled heel (part of their IGS - Impact Guidance System that has been in a number of their shoes for more than a decade) leading into the plastic Trusstic segment. I didn't get the opportunity to wear the Nimbus in the rain, but I did happen upon a few grass front yards overflowing from sprinklers, and I had zero traction problems. 

The shoe is relatively heavy, but I don't know where the fault of that lies. FlyteFoam is dense and there are many elements to glue together, so it may pack on the extra weight there, or it may be the thick rubber outsole, and or is the Trusstic system that contributes.

Hope: The outsole is the glaring flaw in the execution of the Nimbus 21. The forefoot rubber is way, way too soft. Poke it with a finger and it depresses alarmingly easily. It also gets chewed up easily on the run. Blown rubber isn’t the most durable compound, but it makes me queasy to see a ton of noticeable wear in the first 30 miles for a model at this price point. The saving grace may be that there’s a lot of rubber to burn and wear may decelerate over the life of the shoe. I noticed that the firmer heel rubber doesn’t appear to suffer from this problem. I noticed distinct forefoot mushiness on the run, and I attribute that to the softer rubber. Grip, however, is excellent.

Sam: The front outsole has considerably softer forefoot rubber than 19. The prior front guidance line which I never really felt working in the 19 is eliminated as is the lateral plastic Trussic piece.

Most significantly the giant slabs of firm yellow forefoot rubber is gone replaced by softer blown rubber. The forefoot feel in combination with Propel was notably less harsh as a result with the 21 also more flexible, always a good thing.

Ride

Jeff: The Nimbus 21 is a very smooth daily trainer that you can put a lot of miles into. The firm cushioning makes for a responsive and upbeat ride, though it felt a little cumbersome when I picked up the pace. That said, I have a substantial gripe about this shoe - it beats me up. It really picks on me like the neighborhood bully. Every time I ran in the Nimbus the run itself went great. The shoe felt good underfoot, I didn't have any heat issues, and everything felt fine. It may sound like a negative, but if you've had issue with shoes you know that boring runs are good things and the best shoes are usually the ones that disappear underneath your foot. My issue showed up the following morning, in the form of intense leg and hip pain. Seven easy miles in the Nimbus 21 did more damage to my legs than intervals in New Balance 1400v6 or Altra Escalante Racer, two shoes with substantially less cushioning. I had one run in the Nimbus that left me feeling like it should, but all the rest just wrecked my legs. Not to say that this is an expected result of running in this shoe, but no matter how much I like the Nimbus, it definitely does not like me.

Hope: All things considered, the Nimbus 21 is a pretty smooth operator. The heel transitions quickly for a shoe of this bulk. I think forefoot stability could be improved by employing a firmer rubber compound. I had the thought “it’s like running in sand” in these, and while it’s not that extreme, the squish is very noticeable. If you love a soft feeling shoe, you’ll love the Nimbus 21.

Sam: Not my ideal ride but an improved one over the 19 which was firm and stiff while still well cushioned. There is still to much overall rigid support towards the rear of the shoe for me combined with a dense wide mid foot feel getting in the way of ideal transitions. I don’t agree with Hope that the forefoot is to soft or there are any stability issues up front. The softness she felt could also be in part due to the softer Propel layer just above the outsole.

I am a heel striker and all my runs in the Nimbus were at slower paces and decently enjoyable and certainly way more enjoyable than runs in the 19, my “foot therapy” shoe. It is just not a shoe I would run for anything fast in, so I didn’t. They were well cushioned, transitioned well enough even at slow paces, and unlike Jeff I was none the worse for wear after any run.

Conclusions & Scores

Conclusions

Jeff: The ASICS Nimbus 21 is a well cushioned shoe, if on the more firm side of the spectrum designed to be a heavy duty daily trainer. If you are looking for one shoe to handle most of your runs, or just slot in for long easy miles or a recovery run, the Nimbus 21 will work for you. The toe box is substantial, and the rest of the upper works well to keep the foot in place. The midsole has lots of cushioning, albeit saddled with their Trusstic system to give it possibly too much support to fit into the neutral category. The rubber outsole has more traction than you can shake a stick at, if you are in the stick shaking mood, and provided that the shoe doesn't beat you up, you will get a lot of miles out of this shoe. ASICS FlyteFoam has a nice ride to it, and I could see it being used in other applications successfully.

Jeff's Score 8.75 out of 10

-1 for leaving me beat up after easy runs

-.25 for heavy weight

Hope: My impression of the midsole foam was very different from Jeff’s, but I am also new to the Nimbus line. I felt that the Nimbus 21 delivered softness in every aspect. (Where else have you heard someone describe laces as “huggable?!”) I prefer a lighter, firmer style of shoe that lets me feel more connected with the ground, so this kind of ride it’s definitely not my preference. For runners who appreciate a comfortable workhorse shoe that doesn’t try to reinvent the wheel, the Nimbus 21 would be a good choice.

Hope’s Score 8.5 out of 10

-.25 for no reflectivity (or very limited reflectivity -- my camera flash test didn’t make it clear)

-.5 for fast-wearing, overly soft forefoot rubber

-.75 for weight

Sam: Nimbus fans looking for more of the promised cush should be pleased with this update. It is somewhat softer upper to sole with a bouncier ride and with more forefoot comfort. The upper is state of the art, no catch up this time for ASICS in that department. It is by no means a fast shoe but a steady, supportive trainer which both neutral and mild pronators could run. It should be a great shoe for beginner runners, heavier runners, and now given 2 wide fits and now also a roomier standard fit for hard to fit more problematic feet.

Sam’s Score  9.3/10

-.4 for weight. At least for me 10.8 oz in a trainer is too much for daily use if the weight does not provide a fun lively ride which while improved Nimbus struggles to do. Those who pound hard, aren’t pushing pace or need the support will not be as concerned.

-.3 for overly complex under foot design and feel. Lots going on here and it is felt between GEL, Flytefoams, and Trussic. It all works but just isn’t elegant or as satisfying as it could be. For sure more fun to run than 19 but not as inspiring as many other recent trainers.

Astute readers will see I scored the 19 higher back in mid 2017. While having a state of the art upper and improved ride and feel  the competition in the class has livelier underfoot rides and/or lower weights.

Comparisons

ASICS GEL-Nimbus 21 vs ASICS GEL-Nimbus 19 (RTR review)

For all the reasons mentioned above without changing the basic formula of cushioned and supportive ASICS has improved the Nimbus with a superior and more comfortable upper and a slightly softer and livelier ride.

ASICS GEL-Nimbus 21 vs New Balance 1080v9 (RTR review)

Jeff: This is the most natural comparison I can come up with, but it heavily favors the 1080. Both shoes have lots of firm cushioning, a dense midsole with a very durable rubber outsole, but the New Balance feels better at faster and slower paces. The Nimbus holds the foot better, and has a bigger toe box, but I still favor the 1080.

Hope: The 1080v9 is a faster, more fun shoe. It is in the same class as the Nimbus 21 due to its weight, but that’s where their similarities end. I was able to push the pace a bit in the Nimbus 21, but the 1080v9 is much more capable at speed.

Sam: I agree with Hope and Jeff. While the Nimbus overall foothold and stability is a touch more secure due to its earlier and here maligned “heel clutching” and rear of shoe construction, underfoot the smoothness of the single slab of Fresh Foam and 1 oz less in weight wins out.

ASICS GEL-Nimbus 21 vs Topo Athletic UltraFly 2  Jeff: Another solid comparison, the Ultrafly 2 starts to straddle the line away from neutral and into a more stability shoe with a slightly more dense cushioning material on medial side, but Topo's stability is much more transparent. The Nimbus has more cushioning underneath, but the UltraFly 2 doesn't feel lacking in that department, the upper feels much better, and is more responsive when the pace picks up. I really need to talk Sam into letting me give the UF2 its own review, as it wins this comparison easily.

ASICS GEL-Nimbus 21 vs Brooks Glycerin 16 (RTR review)

Jeff: This feels like Coke vs Pepsi, and it could be a coin flip. The Glycerin is heavier, softer and smoother underfoot, with a more plush upper as well. The Nimbus has just as much cushioning (if not a touch more) but a firmer ride. Both toe boxes are really ample, but the Nimbus holds the foot better. Very similar shoes, and up to the runner who wants softer or firmer ride.

ASICS GEL-Nimbus 21 vs Brooks Levitate 2 (RTR review)

Jeff: The Levitate is heavier, but its midsole has a dense feel, very similar to the Nimbus. The knit upper of the Levitate has a more premium feel, but it doesn't hold the foot nearly as well, especially with the different in heel collars. The ASICS toe box is larger, and both have a lot of rubber underneath. I'd take the Nimbus.

Sam: Disagreeing with Jeff in a way the Levitate 2's ride is unusual and more fun in its smooth pneumatic feel from its single slab of PU foam while the Nimbus ride is complex and less of a piece with all its various midsole parts. This said if I had to pick one of the two for daily easier training and I wanted some support (upper and that complex construction), yet with lots of cushion, I would lean towards the Nimbus

ASICS GEL-Nimbus 21 vs UA HOVR Guardian and HOVR  Infinite (RTR review)

Sam: These two new Under Armour trainers coming February 2019 are clearly in the same class as the Nimbus. They share some design similarities with the UA having a soft bouncy HOVR layer (Olefin wrapped in a mesh web) under foot where Nimbus has Propel. After that the UA construction is simpler with a carrier of firmer foam up the sides and under the HOVR layer. Their uppers are yet softer and more comfortable if a touch less supportive, in a good way for me,  for easier runs. While the Infinite weighs a touch less than Nimbus, it is stiff and harder to transition than Nimbus or even the more than one ounce heavier Guardian which has a lower stack height than Nimbus at 26.5mm vs. 28 mm and a half millimeter more up front at 18.5. The stability Guardian also has a plastic mid foot support piece which is vertical and not really noticed. It runs a touch smoother and more fluidly than Nimbus but its additional ounce is felt so slight nod for me to Nimbus. The lighter higher stack Infinite is just too stiff for me and more awkward all around. Clear nod to Nimbus there. 

ASICS GEL-Nimbus 21 vs Nike Zoom Vomero 14 (RTR review)
Sam: The Vomero 14 was my 2018 Shoe of the Year and while a daily trainer like the Nimbus beyond some similarities in upper construction and fit, with Nimbus roomier in the top box and higher volume overall, there is are big differences under foot. The Vomero is far more flexible up front, and thinner there, so less cushioned with a considerably more responsive push off. They have some rear of the shoe stability features with the Vomero using midsole side walls and the Nimbus the Trussic plus the exoskeleton. The Nimbus is more cushioned at the heel and forefoot If you want a fast and responsive daily trainer close to an ounce lighter chose Vomero, if you want a steady protective and cushioned trainer for more moderate paces chose Nimbus.

ASICS GEL-Nimbus 21 vs Saucony Triumph ISO 5 (RTR review)

Jeff: The Nimbus is lighter than the hulking Saucony, but the Triumph has both a softer and more responsive ride. It's upper is almost unnervingly soft, and while others have had fit issues with Saucony's ISO system, I have not and think the upper holds just fine. As big as the Nimbus toe box is, the Triumph toe box is even bigger. Even though the Triumph is a long/slow/easy run staple for me, I'd pick it over the Nimbus for daily wear.

Hope: I’d pick the Triumph ISO 5 for its lively ride that belies its weight. Its combo Crystal Rubber and blown rubber outsole strikes me as more durable than the Nimbus 21’s outsole -- this matters in a daily trainer. I’ve been a fan of the ISO fit system since the original Triumph ISO and remain a fan.

Sam: The simpler single slab Everun midsole in the Triumph and well executed outsole is just more fun (bouncier) and smoother to run. I would pick the Nimbus upper for its more secure hold. Not a big fan of ISOFit as while it may help fit wider fee,t my narrower feet sometimes struggle to lock down.

Read reviewers full run bios here

Photo Credit: Jeff Beck and Sam Winebaum

The product reviewed in this article was provided at no cost. The opinions herein are entirely the authors'.

Comments and Questions  

Welcome Below!

Please Like and Follow RoadTrailRun

Facebook: RoadTrailRun.com  Instagram: @roadtrailrun

Twitter: @RoadTrailRun You Tube: @RoadTrailRun

RoadTrailRun receives a commission for purchases at the stores below. 

Your purchases help support RoadTrailRun. Thanks!

SHOP RUNNING WAREHOUSE FOR GEL NIMBUS 21
Nimbus 20 on clearance for $99.88!

USA  Men's HERE Women's HERE

FREE 2 Day Shipping EASY No Sweat Returns

Available Now!

EUROPE  Men's HERE Women's HERE

AUSTRALIA Men's HERE Women's HERE