Sunday, January 24, 2021

Nike React Infinity Run Flyknit 2 Review

Article by Michael Ellenberger

Nike React Infinity Run Flyknit 2 ($160)


Black, brown, grey and green, the Nike React Infinity Run Flyknit 2 is here! While Sam took on last year’s model, I’ve been tasked with loading the NRIRF2 (fine, fine, we’ll go with “Infinity Run 2”) with miles, and lending my review. The slick, $160 offering undoubtedly looks cool - slightly more rugged looking than last year’s offering, especially in my Ridgerock/Black/Green Glow/Chile Red colorway - but how does it run? Can it help you, as Nike’s website proclaims, “Leave Injury Behind”?


  • Midsole comfort and ride - even from aging React

  • Heel collar and lacing lock-down

  • Versatility and transition


  • Midsole support and “clip” at arch

  • Upper is slightly baggy in places (“patchwork effect”)



Review Pair (M8.5): 9.6 oz. (272g)

Men’s 10: 10.6 oz. (302g) 

Women’s 8:  8.6 oz. (244g)

Stack heights:

Men’s 10: Forefoot 24mm, Heel 33mm

Women's 8.5: Forefoot 23.4mm, Heel 32.2mm

Tester Profile

Michael is a 2019 graduate of Northwestern University Law School in Chicago, with an interest in patent and intellectual property law. Prior to law school, he competed collegiately at Washington University in St. Louis (10,000m PR of 30:21). He recently finished 2nd at the Chicago Half-Marathon in a PR of 67:43, and was the top Illinois finisher in the 2017 Boston Marathon (2:33:03, 82nd overall). He recently secured a 2:31 marathon PR at the Austin Marathon. 

First Impressions and Fit

Compared to last year’s Infinity Run, the Infinity Run 2 doesn’t have the same svelte, almost minimalist appearance to it - and in the launch colors offered (including my seemingly desert-themed colorway), the shoe doesn’t quite seem to be targeting the same crowd. That’s not to say this isn’t an iterative update over v1 - it is - or that it isn’t bringing back much of the same marketing as the last generation - it is - but simply to say that while last year’s model looked, visually, like an extension of the Epic React or Nike Free line, this looks like a shoe all its own.

That “patchwork” (my word, not Nike’s) Flyknit stood out to me - last year, we had a homogeneous upper, but this year there are all sorts of bits here and pieces there to improve fit. I’ll spoil the “Upper” section by saying it works, mostly - but besides that, much of the shoe is unchanged over 2020’s offering, 


Let’s get on with this upper. There are several tweaks that Nike made to specifically address runner concerns over the previous iteration. In sum, I found the upper here to be comfortable and supportive (especially in the rear-third - a joy, after dealing with several shoes lately with mediocre lockdown!), but slightly voluminous compared to the Flyknit of old.

Nike claims to have updated the Flyknit upper for increased strength and support in the toe, eye-stay and foxing (where runners need it most) - I suspect this is where a bit of that added volume comes in - while still maintaining breathability across the midfoot. In cold weather runs, and some warmer treadmill sessions, I found the upper adequately breathable, even though it does sort of look like a thicker, denser Flyknit material. No complaints there.  

Nike also added Flywire cables through the midfoot (you can see them protruding around the lace eyelets) further increasing lockdown and helping with cornering.  

Most importantly, Nike has tweaked the heel collar - primarily by beefing it up, and adding an execution (similar to what we’ve seen from them before) to reduce some achilles tension. It works splendidly, and I didn’t have any ankle or heel irritation across several different runs and sock lengths.  


As the name suggests, the React Infinity Run Flyknit 2 packs React foam in the midsole - a light, middle-class density foam that, while not Nike’s softest or fastest that would be ZoomX, has become something of a workhorse in Nike’s lineup. In the Infinity Run 2, I think it works splendidly - as I’ll address below, I was consistently impressed with this shoe’s ability to ramp up in paces without feeling clunky - while React has some weird sensitivities (I think it’s less reactive, excuse the pun, in cold weather), it really is a nimble material that never feels sloppy - fast, or slow - and provides some good energy return. 

It’s also very wide through the forefoot, which is not a change from the previous version, but is worth mentioning in its ability to provide stability and help the shoe always feel under control, even when cornering at speed, and despite its relatively high stack height.

But - the midsole holds a bit of a dark secret (or, perhaps open secret) when it comes to stability. The dreaded clip. 

Yes, the Infinity Run 2 is a stability shoe, and while it forgoes the classic medial posting, it adds a medially and laterally-mounted, and long, plastic clip and arch insert that, stability or not, are just plain noticeable. The clip is intended to stabilize the knees, the source of many runner issues more than “prevent” pronation per say. Especially when walking or standing, but in my experience while running, too, you can tell exactly where the Infinity Run 2’s medial stability is built, because it so prominently pressures the arch. It’s not painful - it’s not even necessarily bad, in that it didn’t blister, irritate, or otherwise inhibit my running - but it’s there, and you’ll notice it.


Nike has rounded out the outsole here with some strategically-placed rubber, and it’s plenty effective. While some of its React-based shoes’ outsoles have been slightly lackluster (I’m thinking of some of my particularly questionable icy Lakefront miles in the original Epic React), I’m impressed by what Nike has added here. Moreover, the outsole seems durable - I’ll continue to monitor this as it goes - with very minimal wear showing in my first several runs, even on some rougher (by Chicago standards) terrain. 

The added rubber also helps avoid the issue that’s plagued many of my React-based trainers, which is a sharp rock piercing into the outsole. There are exposed flex grooves here, so that issue may not be entirely alleviated, but know that the relatively soft and vulnerable React is well-covered here.


With React underfoot, it’s no surprise that the Infinity Run 2 is on the softer side, but it still packs a decent bounce, and notably has some energy run when turnover increases. It’s not a ride I would call “snappy,” but while some trainers get sloppier when turning over towards a tempo pace, I found the Infinity Run 2 to take it in stride, and allow for a quick turnover without much nonsense. That is, the toe-off here is clean and comfortable, even when accelerating or running faster. I closed out a treadmill session near tempo pace, and didn’t give a thought to whether I was wearing a 5 or a 10 oz. trainer. There’s some definite upside here.

As mentioned above, that medial clip is a bit intrusive, and noticeable in more situations than I’d like. As with anything in a running shoe, the harder you’re working, the less you notice the little things, but I did feel the narrowed and stiffened arch even when running medium paces. I’ll reiterate - it’s not a sensation that made me want to take off the shoe, or even stop to re-tie. Instead, it’s like feeling some firm feedback on the medial side “pushing” you towards the middle of the shoe. Noticeable, but not disruptive. Some runners may want to try on at their local running store (subject to COVID precautions)  before giving these the full sign-off, though. 

Conclusions and Recommendations

Let’s summarize. The Nike React Infinity Run Flyknit 2 is a lot of the same from last year, with some added tweaks - usually good (improved lockdown, improved heel fit) with a little bad (not quite as snug as I’d like in the upper). There isn’t a tweak where I’d hoped we’d see one (the arch/medial clip), but ultimately, it doesn’t doom the shoe.

Of course, there’s some Nike tax built in here, but Infinity Run 2 packs some awesome features (full React midsole, comfortable and cozy Flyknit upper, medial stability) into a well-rounded trainer. Still, it’s imperfect. At $120, I think this would be a no-brainer. At $160, I think it’s a bit more of a gamble, and I’d encourage those who are able to try it on before jumping into them feet first. 

I plan on keeping this shoe around for easy days and recovery runs, where I can appreciate a little extra stability - and with the knowledge that it can transition readily to quicker paces will be a nice trick in my back pocket (or for when I meet up with faster teammates). 

Michael’s Score: 9.0/10


Nike Zoom Fly Flyknit   (RTR Review

I liked the Zoom Fly Flyknit (now a generation old, over the v3) for its speed and responsiveness, but noted its lack of stability and outsole tack, with its tricky cornering making it a questionable winter pick. Undoubtedly the Infinity Run 2 has improved on those stability mishaps, but at the cost of a more nimble platform. What’s more, I found the Zoom Fly Flyknit’s upper to be expertly snug and supportive - basically a second sock - which I prefer to the slightly looser and more “usual” structure of the Infinity Run 2. But ultimately, these shoes don’t necessarily compete. The Fly Flyknit is a great up-tempo trainer, and the Infinity Run 2 a great easy day option. Just beware the differences in their fit, especially with regards to the upper.

Nike Epic React Flyknit 2 (RTR Review)

I prefer the Infinity Run 2 for daily training - the outsole is more robust, and I appreciate the wider forefoot. Now a generation old as well, I believe the Epic React Flyknit 2 is going the way of the dodo (as we welcome in the ZoomX Invincible (RTR Review) - but the Infinity Run 2 is a better shoe, anyway.

Nike Zoom Pegasus 37 (RTR Review)

The Pegasus 37 brought React to Nike’s long-running line , but also is a bit of a misfire, with an uncomfortable forefoot experience and middling up-tempo performance. The Infinity Run 2 seems to be everything the Pegasus 37 was and then some, with the wider forefoot platform and added stability appealing to even more runners. The uncomfortable arch clip keeps it from getting a completely scot-free recommendation, but I think longtime Pegasus wearers turned off by the 37 may enjoy the Infinity Run 2.

ASICS GlideRide 2 (RTR Review)

ASICS pumped up the cushion in the GlideRide 2, while preserving that distinctive (and fun!) rocker sensation. Though both targeting everyday training, and each wider in the forefoot than your usual trainer, the Nike and ASICS present very different outlooks on midsole technology - Nike packing its novel cushioning technology, ASICS positioning its rocker system for more efficient footstriking. The results are disparate; while the ASICS is fun and fast, it’s also a bit less refined, and I found the ride harsher than its predecessor’s. The Nike doesn’t have quite the upside, but it’s a calmer and more controlled ride, and overall is more pleasant. Runners who want a faster trainer should look at the GR2; those seeking something more stable and consistent should lean towards the Nike.

Brooks Glycerin 19 GTS (RTR Review)

Brooks has brought its stability prowess to the Glycerin line with the Glycerin 19 GTS . The stability in the Brooks is much more muted, despite similarly-positioned technologies (Brooks’ GuideRail system is similar to Nike’s Infinity clip system). The Glycerin is more boring (less dynamic), but certainly more traditional. I’d take the Nike, but those who might be turned off by the Infinity Run 2’s arch element should give the G19 GTS a serious look.

Tested samples were provided at no charge for testing purposes. No other compensation was received for the review of Infinity React. The opinions herein are entirely the author's..

RTR Team's Best of 2020 Articles

Road Running Shoes HERE
Trail Running Shoes HERE
RTR Contributors Best of Run 2020, Year in Review Articles

Comments and Questions Welcome Below!
Please let us know mileage, paces, race distances, and current preferred shoes

RoadTrailRun receives a commission on purchases at the stores below.
Your purchases help support RoadTrailRun. Thanks!

Available Now!
USA  Men's & Women's SHOP HERE
FREE 2 Day Shipping EASY No Sweat Returns
EUROPE Men's & Women's SHOP HERE

Available Now!
Men's & Women's SHOP HERE
Join VIP Family, Get Free Shipping and 15% in VIP Benefits on every order, Details here

Men's & Women's  SHOP HERE

Men's & Women's SHOP HERE
FREE Shipping on most orders over $40

Men's & Women's SHOP HERE


Please Like and Follow RoadTrailRun
Facebook:  Instagram: @roadtrailrun
Twitter: @RoadTrailRun You Tube: @RoadTrailRun


Michael said...


Anonymous said...

Are you going to be reviewing the Infinity Flyknit 3? I’m wondering if the differences between 2 and 3 are enough to warrant an upgrade, or if I should look for the 2 at a discount. Appreciate your help!