Our verdict

The Inov8 Trailfly stands out in numerous ways. We found it to deliver a flexible running experience on trails, suitable not only for running but also for hiking. We were thrilled by its spacious upper and anatomical toebox, which perfectly conforms to the feet for unparalleled comfort. And while we noticed its weight to be slightly heavy for its size, we believe it's an excellent option for those seeking a balance between maximalist and minimalist shoes.

Pros

  • Comfortable and plush insole
  • Anatomic, foot-shaped toebox
  • Versatile for all paces
  • Can double as a hiking shoe
  • Good durability
  • Reasonably priced
  • Great ground feel

Cons

  • Not ideal for heel strikers
  • Slightly heavy for its size
  • Excessive outsole thickness

Audience verdict

89
Great!

Who should buy

We think the Trailfly from Inov8 offers an excellent choice for:

  • Those appreciating the roominess of an anatomical toebox but prefer a shoe with some offset over a zero-drop like Altra.
  • Trail runners seeking a natural ride from a shoe that delivers flexibility, breathability, and moderate cushioning.
  • Adventurers needing a versatile and comfortable shoe suitable not just for trails but also for hiking and urban exploration, making it a superb travel companion.

Inov8 Trailfly

Who should NOT buy

We found that the Trailfly, weighing in at 9.9 oz, feels slightly heavy given its size, which may disappoint those prioritizing lightweight trail shoes. For a lighter alternative, we suggest considering the Hoka Torrent 3 or the Saucony Peregrine 14.

Additionally, we believe the Trailfly lacks the necessary cushioning for long-distance efforts. For those venturing into ultra distances, the Brooks Caldera 6 or the ASICS Trabuco Max 3 would be better choices, offering enhanced support and comfort for extended runs.

Inov8 Trailfly parts

Breathability

Despite being equipped with large protective MET-CRADLE strips at the midfoot and toe cap—which slightly reduce ventilation—the engineered mesh of the Trailfly still provides excellent breathability. After conducting our signature smoke test, we awarded it a 4/5.

Using a light on the cut-in-half upper, we could clearly see how Inov8 has meticulously designed the shoe to ensure both secure lockdown and optimal ventilation. It's quite apparent when observing how the light penetrates certain areas of the upper that the mesh is exceptionally thin.

To further verify this, we turned to the microscope.

Inov8 Trailfly microscope

This allowed us to closely examine the mesh, revealing that it is not only thin but also contains thousands of micro-ventilation holes, contributing to the high rating we assigned.

Inov8 Trailfly micro 2

Upon manually examining the mesh, we also found it to be stretchy and comfortable.

However, we observed that the Trailfly offers variable comfort across different areas—it features plush, pillow-like padding in the tongue but probably lacks a bit of cushioning in the midfoot and heel.

Test results
Trailfly 4
Average 3.3
Compared to 78 trail running shoes
Number of shoes
1
Breathability
5

Durability

Toebox durability

We've already established that the mesh on the Trailfly provides excellent ventilation. But how does it fare in terms of durability? To answer this, we conducted a test using our Dremel.

After applying the Dremel to the upper with a force of 3.2N at 5K RPM like we do in all running shoes, we gave it a durability rating of 3/5.

While this score is good, it's not exceptional. However, given the mesh's ultra-thin construction, we can confidently say that this is an impressive result.

Inov8 Trailfly Toebox durability
Test results
Trailfly 3
Average 3
Compared to 58 trail running shoes
Number of shoes
1
Toebox durability
5

Heel padding durability

With the Dremel already in action, we proceeded to our next test—this time focusing on the heel padding of the Trailfly.

The TF performed admirably, earning a commendable 4/5 for its toughness. This enhanced durability in the heel padding is a significant asset for those who often wear shoes in this area.

Inov8 Trailfly Heel padding durability
Test results
Trailfly 4
Average 2.8
Compared to 56 trail running shoes
Number of shoes
1
Heel padding durability
5

Outsole hardness

After completing our assessments of the upper, we turned our attention to the outsole—one of the crucial components of any trail running shoe.

We began by employing a Shore C durometer to measure the hardness of the GRAPHENE-GRIP rubber. Despite its cool marketing name, the rubber's hardness registered at an average 85.4 HC, which aligns with the standard traction we experienced during our test runs.

Inov8 Trailfly Outsole hardness
Test results
Trailfly 85.4 HC
Average 85.3 HC
We use an average of four tests. The photo shows one of those tests.
Compared to 101 trail running shoes
Number of shoes
72.5 HC
Outsole hardness
95.0 HC

Outsole durability

For our final test with the Dremel, we ramped up the speed up to 10K RPM to really challenge the outsole rubber and assess its durability.

We observed a 0.8-mm indentation after the Dremel had done its work on the outsole, which aligns with our expectations for a compound of average hardness. Consequently, we are not concerned about premature wear and tear, which is reassuring!

Inov8 Trailfly Outsole durability
Test results
Trailfly 0.8 mm
Average 0.9 mm
Compared to 51 trail running shoes
Number of shoes
0.0 mm
Outsole wear
2.0 mm

Outsole thickness

In our lab, we measured the outsole—excluding the lugs—to be 3.2-mm thick, a finding that came as a surprise.

We believe that opting for slightly thinner rubber, perhaps around 1.5 or 2.0-mm, would have been prudent to reduce weight without compromising the outsole's sufficient durability.

Inov8 Trailfly Outsole thickness
Test results
Trailfly 3.2 mm
Average 2.4 mm
Compared to 101 trail running shoes
Number of shoes
0.9 mm
Outsole thickness
6.5 mm

Weight

Our concerns about the weight, as highlighted in the previous section, are significant.

The Trailfly tips the scales at 9.9 oz or 282g. While this might seem reasonable on paper, given the stack height and overall size of the shoe, we believe it should shed at least one ounce for v2.

Inov8 Trailfly Weight
Test results
Trailfly 9.95 oz (282g)
Average 10.34 oz (293g)
Compared to 101 trail running shoes
Number of shoes
7.51 oz (213g)
Weight
13.37 oz (379g)

Cushioning

Heel stack

The Trailfly moves away from the maximalist trend, which is something we appreciate—store shelves are overflowing with bulky shoes, making a more streamlined, natural-running alternative a breath of fresh air.

Despite its departure from maximalism, the Trailfly is by no means a minimalist shoe. With a heel stack of 30.1 mm, it offers substantial cushioning yet manages to avoid the clunky feel typical of other trail shoes.

Inov8 Trailfly Heel stack
Test results
Trailfly 30.1 mm
Average 32.2 mm
Compared to 101 trail running shoes
Number of shoes
16.1 mm
Heel stack
42.4 mm

Forefoot stack

We conducted another measurement in the forefoot, which registered at 24.1 mm.

Although this might appear to be adequate cushioning, it's important to note that the Trailfly has a 3.2-mm outsole, substantial lugs, and a thick insole. These factors together leave just slightly over 10 mm of actual foam in this area.

Inov8 Trailfly Forefoot stack
Test results
Trailfly 24.1 mm
Average 24.4 mm
Compared to 101 trail running shoes
Number of shoes
15.2 mm
Forefoot stack
33.9 mm

Drop

Again, this is certainly not a minimalist shoe, and the heel-to-toe drop is a key reason why.

With a 6.0-mm drop, we can highlight two significant findings: first, it's rare for us to measure an offset that perfectly matches the brand's advertised specifications—this accuracy occurs in less than 1% of our reviews! Second, this balanced drop effectively supports most footstrikes, though it particularly benefits midfoot and forefoot strikers.

Inov8 Trailfly Drop
Test results
Trailfly 6.0 mm
Average 7.8 mm
Compared to 100 trail running shoes
Number of shoes
-0.1 mm
Drop
17.3 mm

Insole thickness

The BOOMERANG (another interesting name...) insole is far from average. At 6.3 mm, it's substantially thicker and is made from small TPU pellets, akin to Adidas' Boost technology. This feature enhances underfoot cushioning significantly, and we can guarantee that you'll definitely feel the difference if you switch the stock footbed for a thinner insole.

Inov8 Trailfly Insole thickness
Test results
Trailfly 6.3 mm
Average 4.7 mm
Compared to 101 trail running shoes
Number of shoes
2.7 mm
Insole thickness
9.8 mm

Midsole softness

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

Transitioning to the midsole, Inov8 incorporates POWERFLOW PRO foam—another catchy name for what is essentially standard EVA, providing typical energy return.

Nonetheless, this foam offers a well-balanced ride which delivers enough ground feel, measuring 18.0 HA in softness on our Shore A durometer.

Inov8 Trailfly Midsole softness
Test results
Trailfly 18.0 HA
Average 23.0 HA
We use an average of four tests. The photo shows one of those tests.
Compared to 77 trail running shoes
Number of shoes
9.1 HA
Midsole softness (soft to firm)
39.0 HA

Difference in midsole softness in cold

EVA foams generally struggle in cold temperatures, but this one manages quite well.

After 20 minutes in the freezer, our subsequent test with the Shore A durometer showed only a 22.9% increase, which is a favorable result.

Inov8 Trailfly Difference in midsole softness in cold
Test results
Trailfly 22.9%
Average 26.8%
Compared to 77 trail running shoes
Number of shoes
0%
Difference in midsole softness in cold
100%

Rocker

Although the Trailfly isn't a minimalist shoe due to its drop and stack height, we appreciate the natural ride it offers. A key factor in this is the absence of a remarkable rocker, resulting in a mostly flat silhouette.

Stability

Lateral stability test

If you're searching for a stability trail shoe, the Trailfly may not meet your needs. It is strictly a neutral shoe that requires proficient running technique, though its midsole sidewalls do offer slight guidance for runners with very mild stability issues.

Heel strikers might find stability really lacking in this model, whereas midfoot and forefoot strikers may experience a bit more forgiveness with lateral movement.

Torsional rigidity

We previously discussed how this Inov8 shoe promotes a natural ride, and another crucial factor is its exceptional flexibility.

Remarkably, we rated it at 1-out-of-5 for flexibility—a score typically seen in ultra-flat, minimalist shoes, which is unusual for a shoe with more than 30.0 mm of stack height in the heel. Best of both worlds?

Test results
Trailfly 1
Average 3.5
Compared to 95 trail running shoes
Number of shoes
1
Torsional rigidity
5

Heel counter stiffness

We found that the heel counter could be pushed and bent with almost no resistance, demonstrating that Inov8 has designed a shoe that fully accommodates natural movements, clearly indicating that stability was not a primary concern.

Test results
Trailfly 2
Average 3.2
Compared to 93 trail running shoes
Number of shoes
1
Heel counter stiffness
5

Midsole width in the forefoot

From our initial run, the Trailfly hit us as a nimble, streamlined shoe. We had previously mentioned that it deviates significantly from the maximalist, ultra-wide models, and we confirmed this with precise measurements of the sole.

In the lab, the first measurement, taken at the widest part of the forefoot, registered at 108.5 mm—that's narrow!

Inov8 Trailfly Midsole width in the forefoot
Test results
Trailfly 108.5 mm
Average 111.9 mm
Compared to 101 trail running shoes
Number of shoes
102.1 mm
Midsole width in the forefoot
126.0 mm

Midsole width in the heel

The heel is even narrower, distancing the Trailfly from heel strikers in our view, yet it also contributes to the shoe's exceptional agility. This part of the TF measured just 82.4 mm.

Inov8 Trailfly Midsole width in the heel
Test results
Trailfly 82.4 mm
Average 89.6 mm
Compared to 101 trail running shoes
Number of shoes
77.2 mm
Midsole width in the heel
109.3 mm

Flexibility

Stiffness

We easily bent the Trailfly with virtually no resistance, but we still had to do our standard 90-degree bend test, which we perform on every running shoe.

In this test, the TF required only 17.9N of force to bend, confirming that this shoe is highly flexible and not stiff at all. And remarkably, it does so with a rock plate integrated into its design.

Test results
Trailfly 17.9N
Average 28.4N
We use an average of four tests. The video shows one of those tests.
Compared to 101 trail running shoes
Number of shoes
10.5N
Stiffness
54.5N

Difference in stiffness in cold

We also tested the shoe's flexibility in cold temperatures by repeating our standard 20-minute freezer stint. The results showed only a 15.8% reduction in flexibility, which is quite impressive. This ensures that the shoe will maintain a consistent feel even in the coldest winters!

Test results
Trailfly 15.8%
Average 35.3%
Compared to 98 trail running shoes
Number of shoes
0%
Difference in stiffness in cold
102%

Grip / Traction

Lug depth

The lugs on the Trailfly are substantial, measuring 3.9 mm, combined with the 3.2-mm outsole for a total of 7.1 mm of rubber underfoot. This thickness, however, tends to overly mute the ride, an aspect we believe should be addressed in the next version.

Inov8 Trailfly lugs

Turning to the lugs, we observed various patterns, predominantly chevron-shaped, interspersed with other shapes along the sole's perimeter. This design aims to boost lateral traction and enhance durability.

Inov8 Trailfly Lug depth
Test results
Trailfly 3.9 mm
Average 3.6 mm
Compared to 101 trail running shoes
Number of shoes
1.7 mm
Lug depth
5.8 mm

Size and fit

Toebox width at the widest part

The fit of the Trailfly is exceptionally spacious, offering ample room for your feet. Our measurements revealed a generous 100.2-mm width at the widest part of the toebox, ensuring that even those with wider feet will enjoy a comfy fit.

Inov8 Trailfly Toebox width at the widest part
Test results
Trailfly 100.2 mm
Average 98.7 mm
Compared to 101 trail running shoes
Number of shoes
92.0 mm
Toebox width at the widest part
104.9 mm

Toebox width at the big toe

However, it's our second measurement that truly showcases the unique design of the Trailfly.

Inov8 Trailfly Anatomic

This model features an anatomical toebox similar to Altra shoes, designed to follow the natural shape of the feet rather than tapering like a typical running shoe. That's why we measured a massive 86.8 mm in this part of the shoe, which also explains the distinct look of the Trailfly on this picture, right?

Inov8 Trailfly Toebox width at the big toe
Test results
Trailfly 86.8 mm
Average 79.0 mm
Compared to 63 trail running shoes
Number of shoes
70.5 mm
Toebox width at the big toe
92.1 mm

Tongue: gusset type

The tongue is semi-gusseted, which means it's partially attached to the sides.

As visible in the image below, the gusset extends toward the toebox—a notable feature that ideally should be standard in every shoe within the Trailfly's price range, yet is often absent.

Inov8 Trailfly Tongue: gusset type
Test results
Trailfly Both sides (semi)

Comfort

Tongue padding

While this shoe may not have a maximalist midsole, it certainly boasts a maximalist tongue! At 9.0 mm, it is exceptionally well-padded—perhaps even a bit too much for our taste.

Inov8 Trailfly tongue

The lacing system is effective, though the laces are somewhat long.

Although the padding provides outstanding comfort over the instep, we believe that a tongue 2 or 3 mm thinner could be more suitable for this shoe, helping to reduce its weight slightly.

Inov8 Trailfly Tongue padding
Test results
Trailfly 9.0 mm
Average 6.4 mm
Compared to 101 trail running shoes
Number of shoes
1.5 mm
Tongue padding
12.2 mm

Heel tab

The heel includes a finger-loop heel tab—a thoughtful and convenient feature added by Inov8.

Inov8 Trailfly Heel tab
Test results
Trailfly Finger loop

Removable insole

The perforated insole is not glued, allowing for the replacement with a third-party footbed. However, given its anatomically shaped toebox, finding a compatible insole for the Trailfly can be challenging.

Inov8 Trailfly Removable insole
Test results
Trailfly Yes

Misc

Reflective elements

The Trailfly lacks any reflective features, which is disappointing for a trail running shoe. This omission is surprising, given the importance of visibility for safety on trails!

Inov8 Trailfly Reflective elements
Test results
Trailfly No