Specs and takeaways:
- Name: Nike InfinityRN 4 / Nike ReactX Infinity Run 4
- Weight (men’s size 11): 12.9 oz / 365 g
- Stack height: Forefoot – 30 mm // Heel – 39 mm // 9 mm heel-toe drop
- Sizing: Runs small – go up a half size for the best fit
- Pros: Fantastic Flyknit upper; wide supportive base
- Cons: A bit heavy
- Best for: Easy miles and long days
- Price: $
Where to buy
Now in its fourth iteration, Nike has evolved in its messaging around the Nike InfinityRN 4 to be less about the sustainability of a runner’s legs and more about the environmental impact of sustainability and its carbon footprint. Incorporating Nike ReactX midsole foam rather than Nike React foam, the RN 4 has a supposed “13% more energy return” than predecessors according to Nike. Along with that, the stretchy, Flyknit upper and durable construction makes running in the InfinityRN 4 one of those very solid and stable – though kind of tame – shoes for everyday miles.
Nike InfinityRN 4 Outsole
Laid out with an innie / outie oval waffle pattern, the rubber covering the outsole of the Nike Infinity Run 4 is full-coverage from the rocker in the heel to the toe spring. Under the big toe there is an additional, solid piece of rubber to prevent against wear on toe-off.
This shoe is made to handle the long, easy miles of any runner and the outsole is the first place we see that in this review. The oval cutaways seem to be a direct 50/50 inverse to the road-oriented lugs surrounding them. When it comes to traction, I think the InfinityRN 4 handles everything short of snow really well (and they even held their own on some packed snow – as long as I went super slow!). When it comes to durability, the RN 4 is in fantastic shape having not only handle the 35 running miles I’ve put into it but also in being one of my favorite everyday wear shoes.
Nike InfinityRN 4 Midsole
Foregoing any carbon plates or air bags, the midsole of the InfinityRN 4is simply a good hunk of Nike ReactX foam. This is also where the decrease in carbo footprint comes in by way of the injection molding process which in and of itself results in less waste though here, Nike has worked hard to maintain performance at the same time.
I’ll get into more of my take on the ride of the InfinityRN 4 below but here, let’s look at the base and stability of this shoe. I tend to have a pretty clean gait and am not one to roll my ankles very often – excuse me while I go knock on some wood. Here though, Nike has a very stable upper and the foam works to enhance the connection with the road.
Once the weight begins to shift up and away from the ground the new ReactX foam does indeed bring some good response to the game though nothing approaching ZoomX foam. On a scorecard between “pop” and cushion, cushion definitely comes out on top here though the response is nothing to laugh at.
Nike InfinityRN 4 Upper
Another aspect of a lower carbon footprint in the Nike Infinity RN 4 is in the upper. With the Flyknit material that many – including yours truly – really like for a comfortable fit, this shoe also saves on material waste in the manufacturing process. Laces are fairly standard though and the stretchy tongue becomes a part of a midfoot gusset. The midsole ReactX foam does come up into the domain of the upper in the rear half of the shoe, seemingly taking the place – around the heel – of the bit of plastic plastic found in the rear of the previous React Infinity 3.
I’ve gotta say, I have always loved a good Flyknit upper and this is no different – though sizing is something I’ll address below. In a shoe like this the close-fitting upper means that I don’t feel the need to over-tighten the shoelaces. It also adds a lot of influence to the ride of the shoe and belies the weight which is abundant here.
From a durability perspective, I’ve got zero complaints. With that said though, the color which Nike provided us with is basically sparkling white – with some “light lemon twist” thrown in for good measure – and I have a weird aversion to getting them dirty so it could just be that I’m extra careful (though I’m not)!
Nike InfinityRN 4 Fit
First, let’s talk about the sizing of the Nike InfinityRN 4. You need to go up a half size. Even Nike recommends going up half a size themselves. For me and my men’s size 11, I felt like my foot was always creeping forward in the shoe and while I could get it to shift wack toward the heel, that would mean hammering the laces for full lockdown which I definitely didn’t want to do. Apart from that, my very average-width foot felt at home in this shoe. Again though, this shoe is not going to run true to size for many people.
From the front of the shoe, the toe box has a good amount of room and the stretch inherent in the Flykint upper makes for good space. That said, if you haven’t heeded our advice (or that of Nike and many other reviewers) in going up half a size, the tip of the toe box is definitely where you’re going to notice.
Across the midfoot is where the inner sleeve and laces work together with the Flyknit upper for a comfortable and secure fit. In the past, some Flyknit shoes (particularly those in the Nike Free lineup) could feel a bit sloppy in the upper but Nike seems to have it dialed here.
Moving into the rear of the Nike InfinityRN 4 we find a really well defined heel cup beginning around the collar of the shoe with a great foam backing. Near the bottom, the upper brings some mildly rigid support for holding the heel in place. This is also where we see the most crossover between the soft and bouncy ReactX foam spilling upward into the heel counter to help keep the rear foot from sliding around when cornering.
Nike InfinityRN 4 Ride
Ah yes, the ride. First, is you’re looking for a speed shoe or something with midsole features like carbon plates or airbags, the InfinityRN 4 isn’t that shoe. Nor was it it Nike’s goal with this shoe even in Nike’s older React foam models. Rather, this is a shoe which is setup to handle lots of easy and recovery miles.
When I look at the InfinityRN 4 on paper, the weight is quite a turn off. However, it doesn’t actually feel like a heavy shoe. First, the ReactX foam midsole and its rockered shape make for a smooth and cushy ride. The response from the foam is very nice and does a great job staying away from the marshmallow-y feel that some shoes in this category have historically fallen into.
Second, the hold which the knit upper provides to the foot seamlessly ties it to the sole unit. I know what you’re thinking, “Duh, they’re sewn/glued/welded together dummy” and that’s true. However, I’ve seen countless shoes where the upper feels as though it’s a separate entity altogether from the rest of the shoe and my feet have been all over the place. But not in this shoe.
The ride of the Nike ReactX Infinity Run 4 is one that caters to it being a high mileage daily trainer albeit one which is going to be even better for recovery days. This redesign from late in 2023 sets aside prior React foam models for a quite good update in ReactX foam.
This is likely not going to be a shoe for your speed or tempo days. While the foam isn’t the softest thing on the market – and it does have some rather good response for what it is – those speedy days will probably need something with a plate or simply less cush.
Nike InfinityRN 4 Overall
The Nike InfinityRN 4 is a good, solid shoe. It’s not one which you’re going to love for picking up the pace but it is the type of shoe which tired legs and long steady miles are going to be right at home with. The snug upper and the way in which is works to dispel some of the weight of this shoe is impressive but you’ll still notice that this Nike shoe is not the lightest thing around.
Originally at $160 and now available around $112, this has gone from being pricey for what it is to a good deal. Keep in mind your sizing with this one and have a ball out there getting in the miles.
What are you running in on your easy and recovery run days? Have you tried this shoe?
Where to buy
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