Our verdict

With its feather-like build and ultra-plush confines, it's safe to say that there's no more appropriate name for the NXIS Speed than what it's been given. This kick from KEEN gives each of our steps extra tenacity and vigour, translating to extended rides with nimbleness in tow. And when it comes to forefoot roominess, we discovered that it's hard not to flock to it like bees around honey.

Pros

  • Top-level comfort
  • Immensely breathable
  • Sticks to various terrain
  • Extremely durable outsole
  • Quite lightweight
  • Incredible support
  • Relaxed forefoot fit
  • Accommodating toebox
  • Greatly flexible
  • Locks the heel in place

Cons

  • Unruly shoestrings
  • Too airy for cold winters
  • Not ideal for backpacking

Audience verdict

84
Good!

Who should buy

We recommend the Keen NXIS Speed as a great option for: 

  • Hikers who prioritise comfort looking for a generously padded and well-cushioned shoe
  • Those living in warmer climates in need of an airy, well-ventilated shoe to avoid stuffy and stinky feet
  • Experienced hikers in the market for a lightweight and agile shoe for tearing swiftly across the trails 
  • Hikers with a preference for flexible shoes that still provide good stability and support underfoot. 

KEEN NXIS Speed hjkbj

Who should NOT buy

The NXIS Speed's plush midsole isn't ideal for schlepping heavy payloads across long distances. we recommend a firmer option like the similarly lightweight Adidas Terrex Trailmaker instead for those multi-day hikes. 

Despite performing quite well in our freezer tests, the NXIS Speed is definitely more of a fair-weather friend. For those planning arduous winter expeditions, we recommend the truly weatherproof Salomon X Ultra 4 GTX instead. 

KEEN NXIS Speed hjvj

While this may come off as more of a nitpick, the NXIS Speed's finicky default laces were probably the biggest frustration we had to contend with while testing the shoe. This can be solved either by replacing them or considering the more secure Salomon Outpulse instead. 

Breathability

To get a visual idea of how well-ventilated the NXIS Speed is, we pumped the shoe full of smoke in our breathability test. The result is a rather mesmerising image of plumes of smoke wafting through all areas of the shoe like snakes being charmed out of their baskets. This impeccable performance earns the NXIS Speed a perfect 5 out of 5 for breathability, making it a great choice for those warm summer hikes. With this level of airflow, the shoe should dry up pretty quickly if submerged for one reason or another or after a particularly sweaty trek. As such, stinky feet won't be an issue with the NXIS Speed. 

Compare that to the more winter-oriented Adidas Terrex Swift R3 GTX which only allows smoke to escape in wisps through its perforated tongue. 

Contrary to our expectations, the NXIS Speed blocked out most of the light when we inspected a backlit cross-section of its upper. Only the perforated portions of the upper mesh allowed any sliver of light to peek through. This would ordinarily indicate below-average to mediocre breathability at best but goes to show that there are exceptions to all rules. 

Looking at the NXIS Speed's upper mesh under our microscope clears things up a little better.

KEEN NXIS Speed jkekr

While the braids are dense enough to block out the light, they are woven to form a pattern of gaps that reveal a much airier underlayer of mesh that clearly provides ample airflow throughout the shoe. 

KEEN NXIS Speed Breathability
Test results
NXIS Speed 5
Average 2.8
Compared to 21 hiking shoes
Number of shoes
1
Breathability
5

Durability

Toebox durability

Durability is key when it comes to hiking shoes and the NXIS Speed is equipped with overlays and a rubberized toe bumper to protect its upper mesh from hazards on the trails. We applied our Dremel to a partially protected portion of the toebox mesh to see just how hardy it is. 

After twelve seconds of seemingly brutalising the shoe, we found that our tool hadn't actually done much damage to the NXIS Speed's toebox. As a result, we give it a toebox durability score of 4 out of 5. This means that we can confidently traverse the trails without worrying about snagging and tearing through the upper mesh. 

Test results
NXIS Speed 4
Average 3.7
Compared to 15 hiking shoes
Number of shoes
1
Toebox durability
5

Heel padding durability

Next, we turn our attention to another vulnerable area of the shoe; the heel collar. Our Dremel makes quick work of the lining and kicks up a flurry of debris. 

However, with the NXIS Speed's heel counter being as robust as it is, we found that there was still quite a fair amount of padding left over after the four-second test was up. This leads us to give the NXIS Speed a heel padding durability score of 3 out of 5. An average performance like this doesn't give us much cause for concern with normal use over the lifetime of this shoe. 

KEEN NXIS Speed Heel padding durability
Test results
NXIS Speed 3
Average 3
Compared to 14 hiking shoes
Number of shoes
1
Heel padding durability
5

Outsole hardness

Pressing our durometer against the NXIS Speed's outsole yields a slightly softer-than-average reading of 80.5 HC. This should still be hard enough to provide a good balance of durability and grip. 

KEEN NXIS Speed Outsole hardness
Test results
NXIS Speed 80.5 HC
Average 84.6 HC
We use an average of four tests. The photo shows one of those tests.
Compared to 21 hiking shoes
Number of shoes
65.0 HC
Outsole hardness
94.1 HC

Outsole durability

We fired up our Dremel one last time to 10K RPM and applied it to one of the NXIS Speed's lugs with 3.2N of force. This seems to have little effect on the shoe as our tool's grinding element isn't able to bite into the rubber very well over the course of the twenty-second test. 

Using a tyre tread gauge to assess the damage, we found that only 0.5 mm of material was shaved off the lug. This is less than half of what the average hiking shoe loses, making the NXIS Speed's outsole extremely durable even in the face of extreme wear and tear. With a total of 7 mm of rubber to go through, we expect the NXIS Speed to last well beyond 500 miles of hiking before showing any real signs of damage on the outsole. 

KEEN NXIS Speed Outsole durability
Test results
NXIS Speed 0.5 mm
Average 1.0 mm
Compared to 14 hiking shoes
Number of shoes
0.0 mm
Outsole wear
2.0 mm

Outsole thickness

With 3 mm of rubber making up the outsole according to our caliper measurements, the NXIS Speed falls in line with our current lab average. 

KEEN NXIS Speed Outsole thickness
Test results
NXIS Speed 3.0 mm
Average 2.6 mm
Compared to 21 hiking shoes
Number of shoes
1.6 mm
Outsole thickness
4.0 mm

Weight

A big factor in how the shoe lives up to its speedy name is how incredibly light it feels underfoot. This allows us to be swift on our feet as we tackle tricky ascents and keeps us from plodding down heavily on quick descents. 

This feathery disposition is borne out on our scale, with the NXIS Speed coming in at a significantly lighter-than-average 11.8 oz (335g). 

KEEN NXIS Speed Weight
Test results
NXIS Speed 11.82 oz (335g)
Average 13.19 oz (374g)
Compared to 21 hiking shoes
Number of shoes
6.49 oz (184g)
Weight
17.14 oz (486g)

Cushioning

Heel stack

We measured the NXIS Speed's stack with our caliper to be 30.4 mm thick at the heel. This is right on par with our current lab average, giving us a healthy amount of foam underfoot to adequately dampen our landings and keep us feeling safe from any hazards below. 

KEEN NXIS Speed Heel stack
Test results
NXIS Speed 30.7 mm
Average 31.4 mm
Compared to 21 hiking shoes
Number of shoes
9.9 mm
Heel stack
39.0 mm

Forefoot stack

The NXIS Speed's stack also falls in line with our current lab average at the forefoot at 20.3 mm thick according to our caliper measurements. This gives us enough foam to feel well-cushioned while still providing a good level of ground feel which allows us to nimbly and intuitively navigate the trails. 

KEEN NXIS Speed Forefoot stack
Test results
NXIS Speed 20.3 mm
Average 20.9 mm
Compared to 21 hiking shoes
Number of shoes
10.7 mm
Forefoot stack
31.0 mm

Drop

With a 10.4 mm offset in its stack, the NXIS Speed shouldn't feel too different from the average hiking shoe. 

KEEN NXIS Speed Drop
Test results
NXIS Speed 10.4 mm
Average 10.5 mm
Compared to 21 hiking shoes
Number of shoes
-0.8 mm
Drop
15.9 mm

Midsole softness

Note: a low durometer measurement equals a soft material, whereas a high measurement means it's firm.

We pressed our durometer against the NXIS Speed's midsole and got a softer-than-average reading of 20.9 HA. 

KEEN NXIS Speed iuvh

This level of softness provides us with incredibly well-cushioned landings and keeps our feet feeling fresh and easy even during our longer and more gruelling test hikes. 

On the other hand, we don't recommend this shoe for extended backpacking trips as lugging heavy loads with such a soft midsole underfoot can lead to foot fatigue and imbalance over time. For a shoe with a firmer midsole that's more conducive to being a beast of burden, check out the Adidas Terrex Trailmaker as an alternative. 

Test results
NXIS Speed 20.9 HA
Average 27.5 HA
We use an average of four tests. The photo shows one of those tests.
Compared to 21 hiking shoes
Number of shoes
13.5 HA
Midsole softness (soft to firm)
39.0 HA

Midsole softness in cold

Note: a low durometer measurement equals a soft material, whereas a high measurement means it's firm.
KEEN NXIS Speed Midsole softness in cold

Difference in midsole softness in cold

Despite being more well-suited to warm hikes, the NXIS Speed's midsole performs incredibly well in cold conditions. After leaving the shoe in our freezer to chill for twenty minutes, we found that its midsole only became 7.8% firmer; making it much more consistent than the average hiking shoe as the weather changes. Furthermore, with a durometer reading of 22.5 HA, the NXIS Speed's midsole remains softer than the average for hiking shoes at room temperature. As such, the NXIS Speed should feel just as well-cushioned and comfy underfoot during winter hikes, given it's paired with a pair of warm socks. 

Test results
NXIS Speed 7.8%
Average 17.3%
Compared to 21 hiking shoes
Number of shoes
0%
Difference in midsole softness in cold
100%

Insole thickness

Further contributing to the NXIS Speed's incredibly soft and forgiving ride is its chunky insole which we measured to be 8.2 mm thick. This gives us a luxuriously well-padded and supportive landing surface within the shoe that complements the midsole cushioning extremely well. Fallen arches were the furthest thing from our mind while testing this shoe. 

Test results
NXIS Speed 8.2 mm
Average 5.4 mm
Compared to 20 hiking shoes
Number of shoes
2.6 mm
Insole thickness
8.6 mm

Stability

Lateral stability test

While a soft midsole doesn't usually bode well regarding a shoe's stability, we were pleasantly surprised with how stable the NXIS Speed felt as we shifted our weight from side to side.

This feels balanced enough to take on easy to moderate trails, though we wouldn't recommend attempting anything too challenging or going too far off the beaten path with the NXIS Speed. 

Torsional rigidity

The NXIS Speed didn't put up much resistance as we bent and twisted the shoe in our hands, leading us to give it a torsional rigidity score of 2 out of 5. This doesn't contribute to the stability of the NXIS Speed as much as it helps make the shoe feel quite comfy and natural underfoot. 

Test results
NXIS Speed 2
Average 3.4
Compared to 21 hiking shoes
Number of shoes
1
Torsional rigidity
5

Heel counter stiffness

The heel counter, on the other hand, earns a perfect 5 out of 5 as we were barely able to get it to budge during our manual assessment. This serves to effectively lock our heels in place and mitigate any excessive rolling in our gait that might lead to instability in our stride. 

Test results
NXIS Speed 5
Average 3.6
Compared to 21 hiking shoes
Number of shoes
1
Heel counter stiffness
5

Midsole width in the forefoot

The NXIS Speed's midsole isn't quite as broad as our current lab average at only 103 mm wide at the forefoot. Nevertheless, it still provides a good surface area of grippy lugs to keep us feeling surefooted during our stride. 

Test results
NXIS Speed 103.0 mm
Average 110.3 mm
Compared to 21 hiking shoes
Number of shoes
103.0 mm
Midsole width in the forefoot
117.6 mm

Midsole width in the heel

The midsole is also a little shy of our lab average at the heel, measuring 84.8 mm wide according to our caliper. 

KEEN NXIS Speed Midsole width in the heel
Test results
NXIS Speed 84.8 mm
Average 86.7 mm
Compared to 21 hiking shoes
Number of shoes
64.2 mm
Midsole width in the heel
101.6 mm

Flexibility

Stiffness

We secured the NXIS Speed to our workbench and found that only 15.5N of force is needed to bend it 90 degrees. This is much more flexible than the average hiking shoe, allowing the NXIS Speed to conform with the natural flexion of our foot with ease throughout our stride. 

This further explains the NXIS Speed's natural and forgiving ride that feels easy on the foot for as long as we have the shoe on. 

KEEN NXIS Speed Stiffness
Test results
NXIS Speed 15.5N
Average 29.4N
We use an average of four tests. The video shows one of those tests.
Compared to 21 hiking shoes
Number of shoes
1.8N
Stiffness
54.0N

Difference in stiffness in cold

As with our previous freezer test, the NXIS Speed performed more consistently than average when we repeated the stiffness test, becoming only 25% stiffer once the shoe was appropriately chilled. With 19.4N now needed to bend the shoe to the desired point, it's more flexible than the average hiking shoe at room temperature. While we still wouldn't recommend it for brutally cold or very wet/snowy expeditions, the NXIS Speed will do just fine during brisk winter hikes. 

Test results
NXIS Speed 25%
Average 29.6%
Compared to 21 hiking shoes
Number of shoes
0%
Difference in stiffness in cold
100%

Grip / Traction

Lug depth

Using our calliper, we measured the NXIS Speed's multi-directional, chevron-shaped lugs to be 4 mm thick, putting them on par with our current lab average.

KEEN NXIS Speed vh

These are aggressive and grippy enough to bite into and provide excellent traction over a variety of surfaces, wet or dry. 

KEEN NXIS Speed Lug depth
Test results
NXIS Speed 4.0 mm
Average 3.9 mm
Compared to 21 hiking shoes
Number of shoes
2.1 mm
Lug depth
5.0 mm

Size and fit

Toebox width at the widest part

We measured the NXIS Speed's toebox to be 103 mm wide at its widest point. This is slightly roomier than average and means that the shoe should accommodate most foot shapes comfortably while still providing a secure fit. Only those with very broad feet might experience hotspots during longer hikes as the feet start to sell up from repeated impact. 

KEEN NXIS Speed Midsole width in the forefoot
Test results
NXIS Speed 103.0 mm
Average 100.6 mm
Compared to 21 hiking shoes
Number of shoes
94.6 mm
Toebox width at the widest part
107.7 mm

Toebox width at the big toe

The NXIS Speed's toebox doesn't taper as much as the average hiking shoe does at 89.6 mm wide in the area around the big toe. This is much wider than our current lab average and gives the NXIS Speed a more natural foot-shaped silhouette that gives us plenty of real estate for our toes to splay our comfortably during our test hikes. 

KEEN NXIS Speed Toebox width at the big toe
Test results
NXIS Speed 89.6 mm
Average 81.7 mm
Compared to 21 hiking shoes
Number of shoes
68.8 mm
Toebox width at the big toe
108.6 mm

Tongue: gusset type

The NXIS Speed's tongue is non-gusseted. On the one hand, the omission of a gusset does serve to keep some weight off the shoe, it does, on the other, mean that we did have to contend with the occasional bit of debris making its way into the shoe during our test hikes. 

Test results
NXIS Speed None

Comfort

Tongue padding

We measured the NXIS Speed's tongue to be 8.5 mm thick according to our caliper. While this is a little shy of our current lab average, it still provided us with excellent comfort across the instep and effectively protected us from lace bite no matter how tightly we laced up the shoe. 

KEEN NXIS Speed Tongue padding
Test results
NXIS Speed 8.5 mm
Average 9.5 mm
Compared to 21 hiking shoes
Number of shoes
5.0 mm
Tongue padding
17.0 mm

Laces

This brings us to one of the main bugbears we faced when testing this shoe; namely the laces. We found the default set to be a little too long to lack some form of lace garage that keeps them in place. What's more, they're frustratingly easy to come undone, leading to frequent re-lacing pitstops while testing the NXIS Speed. 

KEEN NXIS Speed Laces

Heel tab

The NXIS Speed features a handy finger loop at the heel to facilitate sliding the shoe on quickly and smoothly. 

KEEN NXIS Speed Heel tab
Test results
NXIS Speed Finger loop

Removable insole

The NXIS Speed's chunky insole is removable, so those in need of custom orthotics can use them with this shoe. 

KEEN NXIS Speed Removable insole
Test results
NXIS Speed Yes

Misc

Reflective elements

With no reflective elements to be found on the shoe whatsoever, we don't recommend hiking along badly-lit roads at night in the NXIS Speed without using additional high-vis gear. 

KEEN NXIS Speed Reflective elements
Test results
NXIS Speed No