Inov8 Trailfly Max review

The Inov8 Trailfly Max should be on your radar if:

• you are after a foot-shaped trail shoe with plenty of wiggle room for toe splay and swelling
• you need a trail shoe with excellent impact protection for covering long distances on predominantly hard-packed terrain and rocks
• you want a highly regarded outsole with superior grip and durability

The Inov8 Trailfly Max feels most at home on hard trails, rocks, and moderate mixed terrain. If you need a well-cushioned shoe for tackling more technical routes and muddy patches, check out the Trailtalon Max instead.

Another reason to look away from the Trailfly Max is if you have flat feet/overpronation or prefer enhanced stability and support, particularly in the rearfoot. The Xodus Ultra 4 from Saucony matches that need perfectly.

We've come to associate Inov8 with down-to-earth profiles and dominant ground feel, but the brand turns that around with the Trailfly Max. It is a max-cushioned shoe that offers excellent impact protection for long distances on hard-packed and rocky terrain.

Recording its shock absorption at 125 SA in the heel and 114 SA in the forefoot, we found the shoe's cushioning to be on par with similarly stacked trail shoes like the HOKA Mafate Speed 4, Topo Trailventure 4, and Saucony Xodus Ultra 4.

The Trailfly Max is equipped with the brand's most advanced Flyspeed Pro foam (different from the Powerflow Pro used in the regular Trailfly). This is Inov8's take on a supercritical, nitrogen-infused EVA foam which promises 'superior energy return.'

And yet, our lab test showed pretty underwhelming and even slightly below-average measurements of 54.8% in the heel and 54.8% in the forefoot. But to be fair, it's not a dull compound per se, and when combined with the Boomerang insole, it does make the Trailfly Max's ride pleasantly responsive.

However, the Flyspeed Pro is still a far cry from Saucony's exceptionally reactive PWRRUN PB foam used in the Xodus Ultra 4 (and both shoes come at the same price point).

As a max-cushioned version of the standard Inov8 Trailfly, the Trailfly Max features the highest stack height in the brand's trail shoe lineup.

Measuring its heel stack with the insole and outsole included, our calliper showed a high reading of 37.1 mm. It is 7 mm taller than the Trailfly's 30.1 mm and is also notably taller than the average.

The shoe's forefoot stack comes very close to the 30-mm mark at 29.5 mm.

While it isn't the tallest we've measured (hello, ASICS Metafuji Trail at 34.4 mm), it does sit in the taller end of the trail shoe spectrum.

Subtracting the shoe's forefoot stack from the heel height gives us a moderate heel-to-toe drop of 7.6 mm. It deviates from the officially stated 6.0 mm but is still within the category average.

It doesn't change the fact that the Trailfly Max is a versatile shoe for various foot strike patterns.

Unlike most other supercritical foams we've tested in our lab, Inov8's Flyspeed Pro is not as soft as we expected.

The compression is pretty moderate here with an above-average durometer reading of 27.5 HA. In fact, it is on the edge of being firm (30 HA or more by our standards)!

But please note that firm doesn't necessarily mean poorly cushioned - you can see the shoe's high shock absorption scores above. What's more, the thick and squishy Boomerang insole on top of it is responsible for giving a pleasantly soft step-in feel.

Inov8 stays true to its natural approach to running, featuring a very moderate toe rocker and an even less pronounced heel bevel in the Trailfly Max.

However, those subtle curves still help make the shoe's towering stack a bit smoother and more agreeable for heel-to-toe transitions.

In 2024, Inov8 joined the ranks of foot-shaped footwear brands like Topo and Altra with its new NaturalFit upper design.

But let's see if the Trailfly Max's actual dimensions live up to the claim.

Having created a one-to-one gel mould of the shoe's interiors, we were able to measure the widest part of its forefoot with a digital calliper.

At 97.9 mm in a men's US size 9 (medium width), the shoe indeed falls into the wide range of trail shoes! And if you need even more space, the Trailfly Max is also available in the wide variant.

The shoe's toebox shape remains wide and rounded around the toes, with no tapering whatsoever.

Measuring its width around the big toe mark, we got another above-average reading of 79.0 mm. That way, the Trailfly Max offers plenty of wiggle room for all five toes, allowing them to spread easily for better ground control and accommodating their swelling on the longer runs.

Few max-cushioned trail shoes surpass the toebox dimensions of this Inov8 shoe, and one of them is the Topo Ultraventure 4 (99.0 mm in the widest part and 83.0 mm in the big toe).

We had concerns about the shoe's wide moulded midguard restricting the toebox fit, but luckily, that's not the case!

Its vertical space proved to be on par with the average, with a toebox height of 27.1 mm. We experienced no pressure on the top of our toes or toenails.

Even though the Trailfly Max is primarily designed for flatter, hard-packed terrain, you want to feel prepared for facing some smooth and wet surfaces like rocks, boulders, or wood.

And we are delighted that the brand's Graphene Grip outsole lives up to the hype in that respect!

Recording the shoe's forefoot friction coefficient at 0.65 on wet concrete, we can confirm that the Trailfly Max will keep you surefooted on those tricky patches.

With a calliper measurement of 3.4 mm, the Trailfly Max's lug depth was only slightly short of the stated 4 mm.

It's a perfect middle-ground for mixed terrain with occasional rocks, grass, moss, and light mud. But if you need a more aggressive and spaced-out tread pattern for deep mud, you are better off with the Inov8 Trailtalon Max (if you want an equally max-cushioned shoe but with 6 mm lugs).

The difference in shoe purpose becomes particularly apparent when putting the Trailfly and the Trailtalon outsole designs side-by-side.

The wider, smoother, and more closely spaced lugs on the Trailfly Max are more suitable for hard-packed terrain.

Despite its substantial stack height, the Trailfly Max turned out to be notably more flexible than its counterparts with a similar design!

A deep flex groove in its outsole and a pliable material in the upper conspired to allow the shoe to bend quite effortlessly in the forefoot. Our shoe bending test revealed that this Inov8 shoe requires only 12.2N to bend by 30 degrees!

Tipping the scale at 10.2 oz (289g) in a men's US size 9, the Inov8 Trailfly Max has a fairly moderate weight for its build. Curiously, it's not that much heavier than the standard Trailfly shoe for daily runs (9.9 oz/282g).

It weighs similarly to its close competitors, the HOKA Mafate Speed 4 10.4 oz and the Topo Ultraventure 4 (10.1 oz).

Large panels of exposed mesh on top of the Trailfly Max suggest a good amount of airflow.

But taking the shoe through a series of breathability tests, we found that it is only moderately ventilated.

Although there is a steady, medium-thick billow of smoke coming out of the shoe's toebox...

...and the toebox material is quite transparent itself...

...we couldn't rate the Inov8 Trailfly Max's breathability any higher than 3/5, given how much more airy other trail shoes are.

Stability is definitely not this Inov8 shoe's forte, and we could feel the brand prioritising a more natural underfoot experience even in such a max-cushioned option.

With its high stack, narrower platform (particularly in the midfoot), and the absence of stabilising components, the Trailfly Max is a neutral shoe through and through.

In addition to its flexible forefoot, the shoe also proved to be fairly pliable torsionally. Our hands didn't face much resistance in a manual twisting test.

Thus, we lowered the Trailfly Max's torsional rigidity score to 3/5.

This is not the best news for runners looking for more support in their trail running shoes, but it is an advantage for athletes who find comfort in shoes that move along with their feet.

The Trailfly Max's heel counter has become a major stumbling block for us (and for many other runners, too!).

Having practically no rigidity to it, this part of the shoe received a very low stiffness score of 2/5 in our manual test. In addition to being super flexible, it is also very minimally padded and sits pretty low against the ankle. This is especially evident when comparing the shoe's silhouette to the Mafate Speed 4, where the collar extends high up the Achilles.

Heel strikers in particular may notice the lack of secure lockdown in this area.

Flipping the shoe upside down, we could see how narrow the shoe's midfoot and heel are in relation to the forefoot.

But at least the Trailfly Max grants some side-to-side stability through its decently wide forefoot base. Our calliper measured the width between its most extended contact points at 108.8 mm. This is slightly below the average but still sufficiently broad.

The heel, on the other hand, turned out to be quite slim at 83.0 mm, which is notably narrower than the average.

And if you put it against the other max-cushioned ultra shoes, you will be even more surprised: Topo Ultraventure 4 (87.8 mm), Saucony Xodus Ultra 4 (97.3 mm), and HOKA Mafate Speed 4 (101.1 mm).

The Inov8 Trailfly Max features a pretty wide and solid synthetic reinforcement around the toebox.

However, it doesn't cover the specific toebox area we test (we keep it consistent across all shoes), and so we tested the limits of the shoe's exposed mesh panel.

Curiously, the material refused to give in so easily, developing some scuffing but not a see-through hole! Because of that, we kept the shoe's toebox durability score at a decent 3/5. But we would stay away from rock edges and sharp vegetation if we wanted to help the shoe's upper last longer.

The mesh lining inside the Trailfly Max's collar didn't falter in our Dremel test, but it wasn't particularly impressive either.

That landed the shoe's heel padding durability score at an average of 3/5.

Infused with graphene, the world's strongest material to date, the rubber outsole of this Inov8 shoe did not disappoint!

After an 18-second standoff with our Dremel, the material developed less than a millimetre of damage (0.7 mm to be precise), confirming its hard-wearing nature.

But please note that the amount of rubber is not very abundant in this Inov8 shoe. It proved to be thinner than average at 1.4 mm, according to our calliper.

But this is what helps to make the Trailfly Max lighter and more flexible as a tradeoff.

Like all the recent shoe releases from Inov8, the Trailfly Max is equipped with the acclaimed Boomerang insole.

By now, we can instantly recognise this insole even in a blindfold test because it is so notably thicker and cushier than the vast majority of trail shoe insoles! Our calliper measured this one at 6.7 mm in the heel.

Comprised of expanded TPU beads, it feels a bit like Adidas Boost, offering a generous squish underfoot. We also believe that it contributes to the shoe's energy return!

The Boomerang insole is easily removable.

But if you intend to replace it with a custom orthotic, keep in mind that you will need a wide-shaped insert to match all that forefoot space!

For those considering the Trailfly Max for the chilly season, keep in mind that its moderately soft midsole tends to get 22% harder. Reaching a durometer reading of 33.5 HA in our freezer test, the shoe's cushioning made it into the firm range in 20 minutes.

The absence of reflective elements on the Trailfly Max makes you invisible in low-light running conditions.

Overall, Inov8 keeps internal padding at a minimum throughout the Trailfly Max's upper.

It features additional padding in the centre of the tongue, reaching 8.0 mm at its thickest point to reduce lace bites and pressure points.

Even though we have a knock on the shoe's rearfoot lockdown, we found its midfoot hold highly secure. This is thanks to the Met-Cradle overlays on the outside and a semi-gusseted tongue on the inside.

Overall, we believe that the Inov8 Trailfly Max is reasonably priced in relation to trail shoes from other brands with similar build and features. It is a £20 step-up from the standard Inov8 Trailfly (£150), offering more abundant cushioning for long distances up to an ultra.

A handy finger loop at the back of the shoe's collar helps with the on-and-off.