Monday, August 14, 2023

Nike InfinityRN 4 Multi Tester Review: 8 Comparisons

Article by Dominique Winebaum, Jeff Beck and Sam Winebaum

Nike InfinityRN 4 ($160)


Sam: With the InfinityRN 4 Nike focuses on comfort top to bottom with a big 39mm heel 30mm forefoot stack of a new soft and bouncy React X foam and a Stretch Flyknit upper. Weight increases 18g over the prior Infinity to 11.16 oz / 316g in US9. 

The Infinity gets a new React X foam midsole and unlike the prior React in the Infinity, and in other Nike with Reactfaom  it is considerably softer on the run than any Nike I can recall (except maybe the more energetic Zoom X powered Invincible 1 and 2)  and has 13% more “energy return” according to Nike. Processed using direct injection instead of the previous compression molding, the midsole's carbon footprint is reduced 43%. 

Its milder (than prior Infinity) support is all inherent to the geometry without the long double sided plastic clip of prior versions.

Just trying them on it was clear the RN 4 represents a new direction for Nike towards softer riding and friendlier fitting shoes that attempt to bridge running and more mellow lifestyle and everyday wear uses. Let’s see what we found running them but upfront we can say comfort is king here!


Attractive design with option to design with your own colors: Dominique

Comfort top to bottom: Dominique/Sam/Jeff

High stack deeply cushioned soft midsole:Dominique/Sam/Jeff

Breathability: Dominique/Jeff

Upper support is secondary to its high comfort level, also a Con: Dominique/Sam/Jeff

Carbon footprint of React X foam is 43% lower than React foam: Sam


Shoe weight: Dominique/Sam/Jeff

Overly soft midsole with not enough support and slow rebound/response: Dominique/Sam/Jeff

Missed opportunity in not using Zoom X (lighter more responsive foam) as at least part of the midsole: Sam/Jeff

Upper lacks overall support for faster running: too stretchy in the toe box could use more heel counter: Dominique/Sam

Please find the testers run bios at the end of the article after Comparisons.


  Samples:  men’s  11.16 oz / 316g (US9), 12.76 oz / 362g (US11)

                  women’s: 10.65 oz / 300g US9

Stack Height: men’s 39mm heel / 30mm forefoot ( 9mm drop spec) 

$160.  Available now.

First Impressions, Fit and Upper

Dominique:  Last December, I reviewed the Nike React Pegasus Trail 4 GTX (RTR Review), which ended up being one of my favorite shoes of the year, a trail shoe with a hybrid trail and road platform designed with a Gore-Tex Invisible Fit upper.  In my early years of running Nikes were my go-to shoes and it is only recently (via my reviews for RTR) that I am rediscovering the brand.  Mind you, I am not worthy of the Vaporfly super shoes!  Indeed, I am excited for this second tester, the Infinity RN 4, a daily trainer with a super cushioned and comfortable platform.

As stated by Nike, it is advised to size up half a size due to the snug fit.  I received mine in a size 9.5 and the fit is perfect – my regular size is 9.  In addition to hitting the nail with the “up-sizing,” the fit is incredibly comfortable.  So, I am off to a great start after just stepping into the shoes.  

A model with a “brand-new take” that I am discovering for the first time, therefore I will let my colleagues delve into the differences between the ReactX Infinity RN4 and the predecessor Infinity models and React foam vs, React X foam.

The Nike Flyknit upper has been revamped with a knit that is supportive and breathable in its design, along with having an internal elastic Flyknit fit band that keeps the middle of the foot securely in place. In short, the internal elastic Flyknit fit band is a gusseted tongue to add another layer of support in lieu of overlays.  

Though the upper is distinctively comfortable and is supportive, the support level is secondary to the comfort level.  It is definitely the type of upper that is more adapted to cruising/easier paces than tempo.  Likewise, it is not as supportive as my  Diadora Atomo V7000 whose upper is reinforced with overlays. 

The toebox is quite roomy and is lined as a targeted and minimalist approach to help feet stay dry in wet weather. The padding around the collar is very soft and supportive adding to the all-around comfort. The heel is reinforced via an external “heal accent” strap that does a good job at keeping the heel in place.  To be noted, this edition features a heel tab, something that was “missing” in the React Infinity 3.   

You can customize the colorways of your ReactX Infinity RN4 via the “design your own” option using 8 different colors for 12 different parts of the shoe – upper, shoelaces, midsole, and Swoosh… and that is before the option to personalize both right and left shoe with text on the heel accent strap.  The design your own option will cost you an additional $30 with a 4 week delivery time frame.  

I received mine in Guava Ice/Viving Purple and I hope they will keep their fresh look with wear. 

Sam: The words "comfort stretch" are key. This Flyknit is very stretchy and foot shape adaptive, maybe to a fault for low volume feet but likely will be a joy for wider higher volume ones. Again, as with the midsole, Nike is going a new direction with a far more easy going and comfort focused upper and a sharp contrast to the Invincible Run 3’s upper or any prior Nike I can recall.

The mesh is stretchy with raised tufts whose thickness I am guessing helping with support. 

The toe box for sure is stretchy and broad and has no toe bumper stiffening beyond the raised outsole up front. I had good hold but the stretch started to be noticeable at faster paces with some lockdown there starting to go. A bit of toe bumper stiffening may be in order.

Wisely, Nike includes a gusset tongue and midfoot hold is excellent but I do notice a bit of lace bite as I have to cinch the laces quite tight for my lower volume feet to take up the stretch. I doubt higher volume feet will have this issue.

The heel counter is not particularly rigid with rigid heel counters often seen in “support” shoes. The red rear strap provides most of its structure along with the raised midsole side walls further forward.

Nike sent me a half size up from my normal US8.5 and I think it is mostly the right call although I wonder if the slight sense of not enough toe box hold at faster paces would be reduced at true to size. At half size up I will say length is correct at about a thumb's width but with such a soft upper and no real toe bumper getting closer to the front might not be an issue.

I do think I could go true to size with my narrower lower volume foot but those with higher volume feet should try the half size up. 

Jeff: I won’t rehash the specs, but I also was sent half-size up from standard (11 instead of 10.5), and that’s the right call. It fits like many other shoes at 10.5, which is how Nike used to do it ~5 years ago, so maybe they’re going back to that.

The toebox stretch is appreciated, since it’s only adequately wide natively, the stretch makes it much more accommodating. I also appreciate that they put in an extra eyelet for a runner’s loop - something early versions of Infinity Run didn’t have and desperately needed and which is why I now own a leather punch.

The upper is largely great, and I don’t have any real complaints other than the material and color get very dirty very easily. My white pair has lots of gray patches, and only after ~20 miles.

The heel pull tab is well executed, and the tongue has a stretchiness that resembles the last couple of ASICS Nimbus tongues. It’s a little thing, but I definitely appreciate it.


We have a giant 39mm heel / 30 mm forefoot full stack height. The stack height is the same as the Invincible Run 3 and is 5mm more at the heel and 4 mm more at the forefoot than the Infinity Run 3. Compared to the Infinity 3 we do gain 0.7 oz / 20g which can be explained by this increased stack height.


The big stack height and React X foam translates to a super cushioned ride with the extensive well segmented outsole providing some mild response, at the ground stability and decent flexibility.  It also means the RN4 is not a light shoe as my US9 sample checks in at 11.16 oz / 316g. I will say it runs lighter than its weight due to its energetic if soft midsole and 9mm drop geometry.

The RN4 clearly has inherent stability features but I would call them of the most mild variety compared to any I have run recently (Brooks Glycerin GTS, and even Kayano 30 and Puma ForeverRun among others).

The stability starts with the broad platform, 90mm wide at the heel, a moderate 70mm at the midfoot (to help with transitions) and a giant 120mm upfront, the widest I can recall and I think essential to keeping the soft foam up front just stable enough.

The mild support guidance continues with high rear midsole side walls of the same foam as the midsole, so soft and in no way the quite harsh glued in extended plastic clips of prior Infinity. The Infinity was a shoe I just struggled to transition off the heel in due to the clips' rigid nature and strangely they were on both sides of the shoe with the lateral the one that bothered most. The foam walls rise to the same height on both sides of the shoe with the foot sitting down as much as about 15mm into the walls to the top of the insole. Not to worry, the walls are soft and adaptive. Overall I would say the RN 4 is considerably more neutral in ride type than its predecessors with their firmer foam and noticed plastic clips. 

On the lateral side (top below) we have a concave shaping of the side walls to create a lateral crash pad and aid decoupling. It is clearly felt, effective but could be toned down to increase the stability and decrease the compression of the soft foam.

On the medial side (bottom above) the shaping is convex for some stability. Also clearly felt as a touch of additional support but as the foam is soft the support is adaptive to my more neutral strike. It is in no way felt as any additional medial firmness or a sharper edge (as with plastic clips) at the top of the midsole such as in the Infinity 1-3..

Dominique:  The midsole has a new foam made of Nike ReactX, which in the previous Infinity was React foam.  Sam has described at length the midsole, which has an impressive stack height - 39 mm heel/ 30 mm in the forefoot - with the height stabilized via the geometry of the foam.  Despite the stated 13% more energy return of the new foam, the overall feel is on the soft side with not enough energy return rebound for me.  I would also prefer a lower drop with more foam in the forefoot.  

Jeff: ReactX is the latest midsole update we’ve seen, and unlike others (namely Saucony’s PWRRUN+) this update seems to change so much it’s less update and much more a whole new thing. It’s been a couple years since I’ve run in the old React, but I’ve logged hundreds of miles across a few different shoes, and none of them were remotely this soft and squishy. 

The midsole width is truly substantial, which obviously plays a huge part in the massive weight of the shoe. There’s just so much of the dense midsole, and physics still comes into play, so there was no way we were ever going to hit 10oz or less.The support elements are much more subtle than previous versions - which were also fairly subtle except for the plastic clip that always dug into my arch.

I’m with Sam, this is the most neutral this line has been, with seemingly zero support if it’s not needed by the runner's strike type.


Dominique:  We have a waffle rubber outsole for durability with a wide platform underfoot for added stability.  

Jeff: The full rubber coverage (sure, there’s gaps that let you see the midsole, but they’re pretty insignificant) helps give the shoe a bulletproof durability feeling, but that much rubber has to also play a part in the heft of the shoe. For a pretty standard block pattern, it has really impressive traction. 

And the dotted lines that run across the shoe underneath the forefoot illustrates that apparently I have a slightly different foot strike with each foot. Not consequential, but interesting for those of us who geek out on wear patterns.

Sam: Copious durable outsole coverage with plenty of grip. I do wonder if fewer holes or longer bars instead of waffle shapes in the forefoot are in order? This might give the forefoot more response and pop given the soft foam above although, on the other hand, fewer holes might stiffen the shoe some, maybe also not a bad thing

Ride, Conclusions and Recommendations

Dominique:  After a half a dozen runs (4 milers) and a couple of walks, I find that the ride is enjoyable, however it is too much on the soft side and with not enough rebound. The high drop, rocker and flex help propel you forward and keep the foot rolling. 

While my initial positive first impressions have faded quite a bit even though by all means this is a very comfortable shoe.  In comparison to my Diadora Atomo V7000, which I tested back in January, the foothold is not as supportive.  Though the Flyknit upper provides both support and breathability, too much of the support relies on the internal elastic Flyknit band in the midfoot.  I would prefer a tighter hold of the entire foot, as the React Pegasus Trail 4 GTX and the Diadora Atomo V7000 deliver.  

In addition, the foam is too soft and lacks support.  This is impacting the stability of the shoe given the high stack height.  

Also, let's mention the weight of the shoe as a negative.  My tester weighs 10.65 oz / 300g, which is 2 ounces more than my Diadora Atomo V7000 which has yet more stack height of foam. .  

I conclude the RN 4 is a shoe for runners who are looking for a comfortable running shoe with a high stack and high drop for cruiser runs.  

Dominique’s Score: 8.8 /10


Sam: Lots of very friendly cushioning here of the very, very soft and bouncy variety. The ride is all about a pleasant experience and not so much about performance.  The combination of mild rear stability elements and 9mm drop had me easily transitioning forward at any pace, even slow ones and I would say without both the drop and stability it would be a harder shoe to actually run. Often soft high stack shoes (Endorphin Shift 3, Fresh Foam More) can be ponderous at slow paces but not so here. 

At faster paces, due to the upper and the softness of the foam, things were not quite as locked down and got a bit more bouncy of the overly soft variety but, as I focused on hitting the 30mm forefoot squarely I moved along with smiles.  At 11.16 oz weight is up there and I wish it were closer to 10 oz but the lively ride had me mostly forget the weight. Same shoe with Zoom X I say!

If I could suggest improvements it would be slightly firmer foam to give the RN 4 more decisive response and pop, lower weight potentially by using Zoom X, and a bit more dialed in upper with less toe box stretch and a stouter heel counter hold.

There is not as much of the wild Zoom X fun and relative instability of the Invincible Run 1/2 and none of the over prescriptive “guidance” from the plastic rails of the Infinity 1-3 here. And if you are a Pegasus fan with its traditional React and Air, the RN 4 is far more cushioned and not as firm but not as responsive or as fast moving a shoe. Save the Pegs for tempo work and light trails. Compared to the Invincible Run 3, we have more flex and a more sophisticated geometry, easier slower paces manners but not as dynamic faster paced ones or as much cushion protection due to the softness, and while not quite as locked down way up front, a better more comfortable heel hold and more comfort focused upper overall than the latest Invincible. 

For the faster higher mileage runner I see the RN4 as a good easy easy days, recovery miles, and for some long run shoe given its soft mellow ride with plenty of upper room and a touch of mellow guidance to help direct the softness. 

For the more recreational runner or beginner, walker, and those on their feet long hours seeking a soft, highly cushioned, easy to turn over and pleasing experience-top to bottom, the InfinityRN 4 is a new more mellow softer option than React foam shoes.

Sam’s Score: 8.93 /10 

Ride (50%): 8.8 Too soft and not responsive enough for my tastes

Fit (30%): 9.1 Extremely comfortable but front and heel area could use more lock down

Value (15%): 8.9 Should prove durable and outside of running a great casual on feet all day shoe.

Style (5%): 9.3 Modern, cheery, just bold enough


Jeff: Dominique is spot on, it’s very soft and not very responsive. Similarly, I wore the shoe during a number of runs and a few walks, and found it to be a much better walking shoe than a running shoe . There’s a ton of squish which makes for a comfortable experience, but not really a great performing experience.

I think Nike has done the midsole a disservice with the name, for me it doesn’t resemble React in any way. React fans may find themselves upset that it’s so different, but as long as they go into it knowing that the midsole is much much softer than the previous iteration they shouldn’t be surprised.

The massive stack, both in height and width, is obviously the main culprit of the massive heft of the shoe. That said, it doesn’t feel *that* heavy on foot, but the number on the scale is going to keep some runners away from a very comfortable shoe that’ll work well for your easiest days. The upper is similarly comfortable, and while there’s some stretch, I didn’t find them to be insecure - but I have a wider foot than Sam does.

The outsole’s durability/traction ratio is fantastic on both sides, and while I don’t have specs on the type of rubber, I hope Nike continues to use it, especially on some of their trail shoes.

Jeff’s Score: 8.55/10

Ride: 8.5 (50%) Fit: 9 (30%) Value: 8 (15%) Style: 8 (5%)



Index to all RTR reviews: HERE

React Infinity 1-3 (RTR Review)

Jeff: I put some solid miles into the first iteration of the Infinity 1 until I realized that the long heel clip that dug into my arch was never going to go away. It also had a very wide forefoot platform, and a stretchy knit upper, but the much firmer OG React midsole didn’t have nearly the squish of the new flavor of ReactX. 

Sam: I was ever a fan of the first 3 Infinity due to their plastic clips weirdly extending way forward and on both sides. They didn’t dig into my arch but the clip was always present and in the way of transitions and especially so on the lateral side. It is a more “serious” trainer than the new version and a less pleasant one to wear and run and really a completely different shoe with a firmer ride and more stability. 

Invincible Run 3  (RTR Review)

Jeff: Another Nike shoe with phenomenal levels of midsole stack height/width, the Invincible Run 3 is loaded with their much more dynamic ZoomX midsole, and the differences between the two midsole materials are vast, especially when worn against each other. The Invincible is much softer; the ZoomX midsole lets you sink in and then gives a slight feeling of bouncing back - the ReactX in the Infinity 4 doesn’t have the second part. As a result, the Invincible is much more of a performance shoe, even if it’s just being used as a daily trainer.

Invincible Run 1 and 2  (RTR Review)

Jeff: Similar to the Invincible Run 3, the 1 was every bit as bouncy and dynamic, though I found the first version to be a little out of control, especially versus the third iteration. ZoomX allows you to sink in before the bounce back, ReactX just sinks in a little more slowly.

Puma ForeverRun Nitro  (RTR Review)

Jeff: One of the better surprises of the last year, the Forever Run has a pretty substantial high/wide stack of Puma’s excellent Nitro midsole, subtle-to-minimal support elements, and a super grippy outsole with their PumaGrip rubber. Sound familiar? What’s striking is when wearing the Forever Run against the Infinity Run 4, the Nike is softer, more comfortable, and the rubber is substantially more grippy. I didn’t expect that.

Puma Magnify Nitro 2  (RTR Review)

Sam: Puma’s big stack neutral shoe has1mm more heel stack height and the same forefoot stack.  It has a much more reactive yet highly cushioned supercritical Nitro foam midsole which clearly also leads to a weight that at 10 oz  / 284g makes it 32g / 1.13 oz lighter than the RN4 and this is clearly felt. Its upper is non stretch and more secure if a bit pointier and lower way up front but clearly more performance oriented. If you are looking for daily training versatility in a big stack shoe the Puma. If you are looking for soft easy going comfort for easy days, walking, and more casual use the Nike.

ASICS GEL-Kayano 30  (RTR Review)

Sam: Almost the same stack height at 40/30 and somewhat lighter the Kayano is more effective in its inherent stability than the Nike due to its geometric design and slightly firmer and quicker rebounding foam. The Nike has a more mellow easy going vibe (and looks) while the Kayano is a better choice if you need more stability without it getting in your way.

ASICS GEL-Nimbus 25 (RTR Review)

Jeff: ASICS made a big change with the 25th iteration of the Nimbus, and I’ve been one of many runners continuing to enjoy it. This was another on foot surprise - mostly because the Nimbus 25 and the Infinity Run 4 are so similar. I find the ASICS upper a little more comfortable, and the Nike outsole much grippier, but their midsoles and overall underfoot experience are very comparable. The Nimbus is definitely a more dynamic performer, but it isn't like the Infinity vs Invincible.

Sam: I found the Nimbus 25 midsole plenty soft and plenty deep but not nearly as soft as the Nike’s. The Nimbus is clearly a higher performing trainer but for me as a heel striker suffers from an over blocky heel and a harder to toe off less flexible forefoot especially at slower paces where the Nike shines brighter. The ASICS has a similar comfortable and similar fitting upper with a somewhat more secure fit.

Saucony Triumph 21 (RTR Review)

Jeff: My current gold standard well-cushioned shoes, the Saucony doesn’t have nearly the midsole width the Infinity Run 4 has, but it’s similarly soft, while also having a more pronounced bounce back dynamic nature than the Nike. The Infinity midsole is much more dense, but the shoes have similar levels of grip.

Sam: Agreed with Jeff! Soft, dynamic and with no performance compromises for the Saucony.

Tester Profiles

Dominique has run for over 40 years, consistently about 25 miles per week at paces between 10 and 11 minute miles and once a week down in the mid 9 minute miles. She races rarely, but always surprises more hard core runners in her age group when she does. She has a 1985 marathon PR of 3:16 in her second marathon which at the time put her on the top 10 Swiss women’s lists. She is the mother of two grown children, both runners post college, and also enjoys nordic and alpine skiing, tennis, hiking and trekking, and gardening. 

Jeff Beck is the token slow runner of the RTR lineup, and as such his viewpoints on shoe and gear can differ from those who routinely finish marathons in three hours or less. Jeff runs 20 miles per week on roads and trails around Denver, CO (and sometimes on the treadmill when the weather gets too much for a Phoenix native). Jeff only got into running in his 30s, as a result his career PR's are 4:07 for the marathon and 5K at 23:39. Jeff has finished several ultra marathons, from 50K up to 50 miles, and is still debating if he wants to go down that road again.

Sam is the Editor and Founder of Road Trail Run. He is 66 with a 2018 3:40 Boston qualifier. 2022 was Sam’s 50th year of running. He has a decades old 2:28 marathon PR. These days he runs halves in the just sub 1:40 range if he gets very very lucky, training 30-40 miles per week mostly at moderate paces on the roads and trails of New Hampshire and Utah be it on the run, hiking or on nordic skis. He is 5’9” tall and weighs about 164 lbs, if he is not enjoying too many fine New England IPA’s.

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Anonymous said...

Nike shoes are like their target audience. Getting heavier and heavier. While a great company like Saucony is being disregarded by my public with bad sales numbers 🙄

Sam Winebaum said...

@anonymous I am not sure Saucony is the cause of Wolverine's issues. As with Deckers they have other lagging brands.
Sam, Editor

Jeff said...

What's more - if you look at the running community at large, more and more are flocking to Saucony. There was a poll yesterday in the Running Shoe Geeks subreddit asking runners which they'd pick if they could only run in one brand. Saucony had more than 50% of the votes, and there were ~8 options. A decade ago Saucony might not have made the list, and if so, they'd probably be sub 10%.

Anonymous said...
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Anonymous said...

I have always liked React going back to the Epic Reacts. They offered nice cushioning and didn't compact prematurely like EVA would. These seem like a possibility. I really want shoes that eat up easy miles, are gentle on my body and I don't need them to propel me. I have found that the new midsole compounds can be very harsh on the body especially when running easy or slow. The ability to run slowly in trainers was never a question in the past.

The newer ultra responsive midsoles are neat, great for faster running/racing, but they seem to be taking over the whole industry.

I like your thorough reviews, but there is an over the top obsession with adding super responsive foams to every application that doesnt really make much sense.

Sam Winebaum said...

Thanks @anonymous!
The fact is firm or softer, and some are quite firm, the new foams provide a more resilient dynamic ride than the older foams. And they lead to considerably lighter shoes if, often but not always more expensive ones, Puma and Skechers being notable exceptions. As far as runablity indeed some of the geometries and plates are not as slow running as older shoes. That is a function of design and I think especially in race shoes after the very very first Vaporfly in 2017 the trend has been towards more aggressive mainly fast paced run shoes. Again exceptions from Puma and Skechers and to a certain extent Saucony with latest Endorphin Speed 3. I think the trend will shift to more flexible race approaches again with propulsion from plates still in the mix.
Sam, Editor