Nike Free RN NN review

We recommend the Nike Free RN NN as an excellent choice for: 

• Runners with a neutral stride who prefer lightweight and agile daily trainers with a bare-there ride
• forefoot/midfoot striking runners who want a flexible mid-drop road shoe that can bend it like Beckham
• Those in cooler climates looking for a warm shoe that performs well in frigid conditions
• Active individuals in the market for a shoe that can take on other fitness activities and gym days

The shoe's Flyknit upper demonstrates lackluster breathability in our smoke test which makes it a less than ideal choice for warm weather runs. The Allbirds Tree Dasher 2.0 is a more breezy option that also has a sock-like fit.

While the feathery nature of the Free RN NN does allow us to push the pace to a certain extent, it lacks the responsiveness to be a dedicated tempo shoe. We recommend checking out the Saucony Kinvara 14 as a better speedy alternative. 

Additionally, long-distance runners will benefit from a shoe with more protective cushioning underfoot like the Puma Magnify Nitro 2 instead. 

Runners with narrow feet will find themselves floating around in the Free RN NN's spacious toebox. We recommend checking out the Skechers Go RUN Ride 11 for a more snug fit. 

The Free RN NN is a neutral shoe with a ride that's not at all supportive for those with overpronating strides. The Nike Structure 25 is a stability shoe that promotes a more neutral gait that will suit those runners better as daily trainers. 

The Free RN NN has quite a low profile, with its stack measuring only 25.6 mm thick according to our caliper. This is still a good amount of foam underfoot to protect our feet from the harsh impact of landings while keeping us stable and low to the ground. 

We measured the forefoot stack to be 18.7 mm thick which is also quite a bit short of our current lab average. This also affords forefoot strikers a decent amount of impact dampening but a lot more ground feel. 

For forefoot strikers who prefer having more protective foam at the forefoot, the Brooks Levitate Stealthfit 6 is another sock-like shoe that we recommend looking into. 

The difference in our stack measurements leaves the Free RN NN with a heel drop of 6.9 mm, thus classifying it as a mid-drop shoe. This offset is quite versatile as it will suit the stride of most runners whether forefoot, midfoot, or heel striking. 

For a better understanding of drop heights, check out this in-depth guide that thoroughly explores the matter. 

Using our caliper again, we measured the Free RN NN's insole to be 5 mm thick. This is ever so slightly thicker than average and leaves us with a nice and cushy footbed to sink into during our landings in this shoe. 

Pressing our durometer against the midsole yields a reading of 26 HA. While this is slightly firmer than average, it still provides a balanced level of cushioning to our landings. 

This somewhat firm nature means that the midsole is keen to retain its shape and has a pretty good rebound as our weight shifts forward in the shoe. As such, the midsole doesn't feel dull by any means. 

That said, while the shoe can handle quick paces, especially by virtue of its featherweight stature, it doesn't have the snappiness or springiness we expect from a speedy shoe that will crack PRs. We recommend looking into the similarly low-profile and sock-like Brooks Levitate Stealthfit 6 for those afflicted with a need for speed.

We placed the Free RN NN in our freezer to observe the effects of cold conditions on the midsole. After twenty minutes, we took another durometer reading of the midsole and found that it only became 10.1% firmer once appropriately chilled. As such, the Free RN NN's midsole is much more consistent than average which means that the shoe's ride won't be compromised by frigid weather. 

Using our caliper, we measured the Free RN NN's toebox to be 104.9 mm wide at its widest point. This is much wider than average and means that broad-footed runners will enjoy an accommodating and comfy fit while those with normal-width feet have a little wiggle room to spare. 

Runners with narrow feet, however, will definitely find this a little too roomy to achieve a secure lockdown at the forefoot. We recommend checking out the Brooks Glycerin Stealthfit 20 as a much more snug alternative. 

The toebox tapers to 80.3 mm wide in the area around the big toe according to our caliper measurements. This is also wider than our current lab average and means that we have plenty of room to splay out naturally within the shoe without butting up against the walls and risking hotspots or blisters.

The Free RN NN's tongue is integrated into the upper as one solid piece, giving the shoe a sock-like fit. As such, we didn't have to worry about slippage and enjoyed a nice and snug lockdown with the shoe essentially wrapping itself around our foot and virtually disappearing from our minds as we started testing it. 

The Free RN NN does very little to mitigate the lateral movements of our stride, making its ride not particularly stable. While this shouldn't be much of an issue for those with a neutral gait, we recommend that overpronators look into a shoe with more corrective features like the Nike Structure 25 or the Brooks Hyperion GTS to avoid injury. 

The Free RN NN put up almost no resistance to our manual manipulations, with us basically able to wring the shoe out in our hands. This earns the shoe the lowest torsional rigidity score of 1 out of 5 on our subjective scale. As such, the shoe is able to contort and twist along with the natural movements of the foot which, while unstable, translates to an extremely comfy and forgiving ride when we are running on level roads. 

The heel is similarly pliable, with no structure to it apart from a pillow of padding that gives the rearfoot some shape. This also contributes to the shoe's barely-there sensation underfoot as it puts no pressure on our tendons and does nothing to mitigate lateral rolling of our heels. 

We found the Free RN NN's midsole to be slightly wider than average at 115.9 mm wide at the forefoot. This gives us more than enough of a base for surefooted landings and toe-offs as forefoot strikers. 

Meanwhile, back at the heel, the Free RN NN's midsole is on par with our current lab average, measuring 90.3 mm wide according to our caliper. This also afforded heel strikers a good landing platform that shouldn't feel unsteady. 

We secured the Free RN NN to our workbench and found that only 6.2N of force is needed to bend the shoe 90 degrees. This is one of the most flexible results we've come across in the lab and means that a brisk breeze could essentially bend the shoe to the desired point. 

This further contributes to the shoe's natural feeling ride that really had us feeling like we were running around barefoot while testing this shoe as it puts up no resistance to the flexion of our foot throughout our gait. 

We also repeated the flex test after leaving the Free RN NN in our freezer for twenty minutes and found that it got 23.4% stiffer. However, it could become 200% and still be much more flexible than the average shoe at room temperature. As such, the Free RN NN will feel consistently flexible and forgiving on the foot all year round no matter how low the temperatures drop. The combination of the shoe's performances in our freezer tests plus its warm upper makes it an excellent wintertime companion. 

As alluded to in the previous section, the Free RN NN is incredibly lightweight. Tipping our scale at only 6.9 oz (197g), it's truly a barely-there running shoe. When combined with its snug, sock-like fit, we had to keep checking our feet during our test runs to make sure they were still on. 

We pumped the Free RN NN full of smoke to get an idea of how breathable it is. As we can see from the footage of the test, it takes quite some time before smoke is finally able to start filtering out the shoe. It struggles its way through the Flyknit upper in wisps that seem to escape haphazardly throughout the shoe. 

The Saucony Triumph 20, meanwhile, is a true smoke show in this test earning it a perfect 5 out of 5. 

This lackluster performance earns the Free RN NN a breathability score of 2 out of 5 which confirms its warm and insulated nature. While this may not be ideal for hot days, it's certainly beneficial as the mercury drops during the cooler months. 

While the light is visible through a cross-section of its upper, the Free RN NN doesn't allow any of it to peek through any pores in the material. This serves to illuminate the shoe's below-average breathability to a certain extent. 

Our microscope provides further clarification as it shows how dense woven the shoe's Flyknit upper really is; with only barely perceptible little gaps that allow any kind of airflow through the Free RN NN. 

For what it lacks in breathability the Free RN NN Flyknit upper makes up for in strength. Firing up our Dremel to 5K RPM to simulate some extreme wear and tear, we set it against the shoe's toebox with 3.2N of force. 

Upon inspecting the damage in the aftermath of the test, we found that our tool had merely frayed some of the outer material and failed to penetrate the toebox all the way. This earns the Free RN NN a toebox durability score of 4 out of 5 which is very respectable for a daily trainer with no protective overlays. 

Next, we set our sights on the heel collar and set our Dremel against the Free RN NN once more. 

It proved to be even more resistant to the abrasive force of our tool's grinding element as after four seconds it was barely left with a scuff. This leads us to give the Free RN NN a well-earned perfect score for heel padding durability. We therefore don't believe that wearing a hole in the heel from excessive rubbing will be the cause of retiring this shoe early.

Pressing our durometer against the Free RN NN's outsole gives us a reading of 79 HC. This is about as hard as our current lab average which usually indicate a good mix of grip and durability. 

To test that last claim, we got the Dremel spinning at 10 K RPM and set it against the Free RN NN one last time. 

After twenty-two seconds of punishment, we found that we had lopped off 0.8 mm of rubber from the outsole. This makes the Free RN NN's outsole about as durable as average and leads us to predict that the shoe should last a good 400 to 500 miles before the tread starts giving out significantly. 

At 2.5 mm thick according to our caliper measurements, the Free RN NN's outsole is a little shy of our current lab average. This is a good amount of rubber to wear through without weighing the shoe down, especially considering the rubber's performance in our last test. However, with the shoe so lightweight already, a touch more rubber would definitely add to the shoe's longevity. 

Nike's approach with the Free RN NN's outsole is unorthodox. They minimized coverage as much as possible to save on weight, while also scoring the rubber and the midsole to form a very minimal tread pattern (as well as to facilitate bending easily as we saw in the previous section). This, surprisingly, provided us with good traction on asphalt roads where the outsole had an almost sandpaper-like quality. However, more slick or wet surfaces did cause us to wobble a bit during our test runs. 

The Free RN NN features a little reflective streak at the lateral side of the toebox. While this provides at least a minimal level of nighttime visibility, we recommend using additional high-vis gear when going for nocturnal runs along dimly lit roads. 

With no tongue per se, we measured the area of the upper above the instep and found it to be only 2 mm thick. As such, the laces still felt quite present across our instep once our foot was locked in and ready to go, however, it wasn't a source of great discomfort once we started running. 

With sock-like shoes notoriously difficult to put on, especially those from Nike, the Free RN NN has, fortunately, furnished us with not one but two finger loops. One at the and another at the top of the tongue. 

Yanking on these two in tandem did make the shoe slightly easier to squeeze into/ 

The insole is fully removable so replacing it with an aftermarket one or a custom orthotic for added arch support is possible if necessary.