Article by Dom Layfield
Inov8 Trailfly Zero ( £140 / $160 / €160)
Introduction
Dom: The Inov8 Trailfly Zero follows a storied lineage of shoes. Its progenitor was the Terraultra G 260, which in 2019 introduced Inov-8’s “graphene-enhanced” outsole material, along with a bulletproof upper and zero-drop stack. RTR reviewers found a lot to like with this shoe, but thought it a little too firm and lacking in cushion for our American tastes. Next was the Terraultra G 270 that added 3 mm more midsole height and introduced Inov8’s TPU-beaded ‘boomerang’ footbed. This was such a hit at RTR that we voted it our 2020 “Trail Shoe of the Year”. In early 2023, we reviewed the Trailfly G 270 v2 update (The ‘Terraultra’ → ‘Trailfly’ renaming was apparently related to a trademark dispute.) Given the accolades awarded to the original G270, Inov-8 wisely didn’t change much, and RTR reviewers were similarly enthusiastic.
New TrailFly Zero (left) and its predecessor, Trailfly G 270 v2 (right).
Dom: This brings us to the new Trailfly Zero. In the intervening two years, ‘Inov-8’ became ‘Inov8’ and made the bold move to tweak the last they use across their entire range of shoes to make it more natural, more similar in shape to a real human foot. I’m very happy about this, and liked the Trailfly Speed, the first Inov8 shoe I tested built on the new last, so much that I recently purchased my third pair. However, the Trailfly Speed is likely too minimal a shoe for many runners, and not well-suited to high-volume training. Consequently I was very excited to receive a pair of Trailfly Zero, hoping for a similar shoe with more cushion.
Dom: The new Trailfly Zero boasts a 23/23 mm zero-drop stack (up very slightly from 22/22 in previous Trailfly G 270 v2 shoe) with full-coverage outsole (G 270 was only partial coverage), and 12 mm of FLYSPEED PRO midsole foam (supercritical, nitrogen-infused EVA). And, of course, all of this with Inov8’s new anatomical foot last.
Pros:
Dom: Excellent forefoot: Great balance of bounce, protection and ground feel.
Dom: Outsole grip
Dom: Durability expected to be excellent.
Dom: Comes in two widths, regular and wide.
Dom: Inov8’s new ‘natural’ last is a clear win for my feet.
Cons:
Dom: Heel retention is a major disappointment.
Dom: Zero drop shoes are not to everyone’s liking. Even I think I would have liked a few mm.
Dom: Flat (even slightly concave) underfoot profile.
Dom: Weight not competitive with lightest shoes, but reasonable for a daily trainer.
Most comparable shoes
Dom: Inov8 Trailfly Speed, Altra Superior, Altra Lone Peak. Topo Pursuit. Hoka Torrent. Nike Terra Kiger.
Stats
Spec Weight: 270 g (size UK 8.5 / US M 9.5 / EU 42.5) according to Inov8 specs
Sample Weight: 293 g / 10.3 oz (US M10, regular width)
Stack Height: men’s 23mm heel / 23mm forefoot (mm drop spec)
Estimated stack of sample shoes: 25 mm
First Impressions, Fit and Upper
Dom: Out the box, my first thought was that the new orange-blue colorway was a little loud. The previous G 270 v2 was also orange-blue, but with a more muted orange confined to the midsole foam. But hey, at least the Trailfly Zero is easy to recognize at a glance. I noticed immediately also the new, anatomical last, making the toe-box less pointy.
Dom: On the foot, what stands out above all else – and no doubt I’ll end up repeating myself here – is that there really feels to be something awry with the heel: it’s low and loose, and doesn’t feel reassuring at all. When I think of Inov8 shoes, I imagine gnarly fell-runners racing over steep, muddy, slippery hills. This shoe feels like it would get sucked off immediately in sticky mud.
Comparison between heel of new TrailFly Zero (left) and predecessor, Trailfly G 270 v2 (right). TF Zero heel hold area is lower and more vertical; G270 cups the heel much more.
The heel collar is too low and too vertical, not cupping around the heel to hold it down, with almost no padding.
Dom: Otherwise, everything else is good news in terms of upper construction and fit. The primary upper fabric is a multi-layer mesh very similar to the fabric used in the G 270 v2. The Trailfly Zero upper feels slightly thicker, with a more slippery fabric facing inward. Durability of the G270 durability has always been a strength, so I have high hopes for the Zero.
Another positive in this regard is that the overlay wraps fully around the forefoot, forming an almost complete rand, protecting the base fabric from abrasion in the high-wear area at either side of the toe crease.
Dom: Personally, I’m very happy with Inov8’s new foot-shaped last, which is not a seismic change, but a useful step in the right direction. The sample shoes that I received were ‘regular’ width, and I was initially disappointed not to have received the ‘wide’ version (as I did with the Trailfly Speed). However, I’m happy to report that even the ‘regular’ width version is still moderately wide, and I had no issues of discomfort or my feet feeling restricted. This made me happy as I feel pretty strongly that too many people squash their feet into narrow shoes, and have got accustomed to this sensation. Some brands that sell shoes in multiple widths end up making their ‘regular’ width narrower: not so with Inov8, it seems.
Dom: With the egregious exception of the heel, the Trailfly Zero feels similar to the outgoing G 270 v2. That shoe managed to do pretty much everything well and the Zero retains these strengths: breathability, comfort, foot hold are all very sound.
Midsole & Platform
Dom: One area where the previous G 270 v2 was not quite as strong as expected was in the midsole. I used that shoe in a couple of 100 km races, and found myself wanting just a little more protection underfoot. Additionally, in my review I grouched that Inov8 hadn’t employed a shiny new bouncy superfoam, but stuck with tried-and-tested “Powerflow Max”.
With the Trailfly Zero, Inov8 have switched in their supercritical “FlySpeed Pro” foam, and stack is nominally up just 1 mm from 22 to 23 mm (although I hand-measured at 25 mm). This change makes the new shoe feel bouncier and more cushioned. Combined with a full coverage outsole that stiffens the forefoot, rock protection is noticeably and usefully improved.
Dom: With most shoes the footbed barely warrants a mention. However, Inov8 have had a trick up their sleeve for the last five years. Their ‘Boomerang’ footbeds have embedded eTPU beads that provide enough bounce to significantly change the feel of a shoe.
Additionally, this construction results in a footbed that can keep its shape over years of use. Nor do they retain water, helping trail shoes dry quickly after water crossings.
Other manufacturers are starting to catch on (Topo Athletic, for example, use a similar footbed in their Pursuit.) RTR reviewers have long appreciated these footbeds and often transplant them to other shoes in order to add a little more cushion and bounce. Personally, I last ran UTMB in a pair of Hoka Tecton X2’s with the Inov8 Boomerang footbed replacing the factory one.
Outsole
Dom: The new generation of Trailfly shoes have full coverage outsoles of Inov8’s in-house G-Grip rubber. This likely increases overall weight slightly (the Trailfly Zero has gained about 17 g / 0.6 oz) but improves grip and avoids regions of exposed midsole where pointy rocks can stab your foot.
Outsole of new TrailFly Zero (above) and predecessor, Trailfly G 270 v2 (below). TF Zero has full coverage outsole, improving grip and rock protection, but is heavier.
The outsole on the Trailfly Zero looks to be identical to that used in the Trailfly Speed, with which I have extensive experience with in all conditions, and have found to be unambiguously excellent.
Dom: That said, there’s nothing other-worldly about this rubber. Don’t get me wrong, it’s great stuff that compares well with other top outsoles. I just don’t find myself dazzled by its freakish grip or shocking durability. We’re talking magna cum laude performance, not summa cum laude.
Ride
Dom: The ride of the outgoing Trailfly G 270 v2 was really nice. It was light, bouncy, flexible, nimble, and fun. The new Trailfly Zero uses an improved midsole foam and gains a hair of stack height, so on paper it ought to feel out of this world. Maybe I’m in grinch mode here, but I wasn’t as wowed by the Zero as I expected to be. Was I just distracted by the sloppy heel? Or is it that I’ve recently been running in heavily rockered race-oriented shoes that roll effortlessly forward?
New TrailFly Zero (above) is flatter underfoot than its predecessor, Trailfly G 270 v2 (below).
The Trailfly Zero feels very flat underfoot, and actually slightly concave when scrutinized closely. I’m sure this is useful when, for example, balancing on a wet log, but for everyday trail use – particularly on the harder surfaces that the ‘Trailfly’ line is aimed at – the lack of rocker makes the shoe feel slow. Additionally, I have no problems with zero-drop running shoes, but here I couldn’t help wondering if a few millimeters of drop might bring the shoe to the next level. The Trailfly Speed has a slight 4 mm drop, and I somewhat wish Inov8 had used that offset here.
Dom: I have to emphasize that I’m quibbling. Setting aside the disappointing heel fit – which can be remedied almost completely by lock-lacing – the Trailfly Zero is an excellent shoe to run in. In particular, I thought the forefoot was near perfect. Stability, grip, ground-feel, comfort, are all rock solid.
Conclusions and Recommendations
Dom: The Trailfly Zero ought to be an easy home run: Take a legendary shoe, and update it to improve on its minor weaknesses. More bounce? Check. More rock protection? Check. Improved grip? Check. Improved foot shape? Check. And make it available in multiple widths for good measure. Regrettably, the inexplicably sloppy fit of the heel forces me to deduct enough points to drop the shoe down from its top-of-the-class grade.
Dom: Otherwise, its strengths are really strong. This is a comfortable shoe that performs well in every condition: it is stable, grippy, nimble, sure-footed, bouncy, protective, and promises excellent durability.
Dom: I do struggle slightly with the “who is this for?” question. Personally, my running shoes tend to be either fairly minimal for daily training (e.g. the less cushioned Inov8 Trailfly Speed is one of my favorites) or maximal for racing ultras. For my taste, the Trailfly Zero is a little overbuilt for daily running, but not cushioned enough (or rockered enough) to work as a long-distance race shoe. Nor is it light enough to be competitive over short distances. On the other hand, if you want one shoe that can do pretty much anything, the Trailfly Zero fits the bill nicely.
Overall score 8.5/10. 😊😊😊😊
Ride: 9 - Stable, predictable, secure, but a little flat underfoot.
Fit: 8 - Forefoot is great, but heel feels loose.
Protection: 10 - Plenty for almost all uses. I stomped hard on rocks and felt no discomfort.
Style: 8 - The orange of my sample pair was a bit loud for my taste.
5 Comparisons
Inov-8 Trailfly G 270 v2 [RTR Review]
Dom: The differences between the new Trailfly Zero and its predecessor are discussed extensively above. To summarize, the Trailfly Zero is a little heavier (293 vs 275 g in US M10), gains a millimeter of stack height (nominally 23 mm vs 22) and is more protective. It is shaped to Inov8’s new anatomical foot last, and is also available in regular and wide width options.
Both shoes are zero-drop, and use Inov8’s TPU-beaded footbed. Trailfly Zero midsole foam is updated to ‘FLYSPEED PRO’ with the outsole upgraded from partial coverage to full coverage graphene-enhanced rubber.
On the foot, the Trailfly Zero feels more substantial and protective than the G 270 v2, but also a little flatter and less fun. Personally, I thought the heel of the Trailfly Zero felt loose and insecure and had to use lock-lacking to secure it properly.
Topo Athletic Pursuit 2 [RTR Review]
Dom: I was initially a little tepid about the Topo Pursuit 2, but over time I found myself reaching for them for my daily training runs, particularly if I didn’t have a clear plan about distance or terrain. I knew that the Pursuit 2 would handle it all. That makes me wonder if I will end up feeling similarly about the Trailfly Zero. Both are immensely capable, go-anywhere, do-it-all shoes with no real weaknesses.
The Trailfly Zero stack is a little lower, giving it a slight edge in stability, and its stealth rockplate means that it provides no less rock protection at the lower height. The Trailfly Zero is a little lighter (at 293 g vs 317 g), but neither are featherweight race shoes. Both are zero drop, and both have similar, excellent TPU-beaded footbeds. If you have slim heels, the lack of heel security in the Trailfly Zero might be an issue, but otherwise, I think the Trailfly Zero wins by a nose.
Altra Superior 6 (RTR Review)
Dom: The zero-drop Superior 6 has 23 mm stack height, which is nominally the same as the Trailfly Zero, but is more flexible and less protective. As a daily runner, I personally prefer the Superior, as my taste leans toward more ground feel. But the Superior is much more limited in its capabilities: I wouldn’t consider racing in it, nor going longer than a few hours. The Trailfly Zero is considerably burlier and more protective. It’s also bouncier than the very neutral Superior. If you want one shoe that can do everything, the Inov8 wins handily. But if you have the luxury of keeping multiple shoes for different roles, then the swiss-army-knife nature of the Trailfly Zero feels like less of a win: “Jack of all trades is master of none.”
Altra Lone Peak 9 (RTR Review)
Dom: The Lone Peak stack height is 25 mm, slightly more than the Trailfly Zero (23 mm), but of the Altra line-up, this is the closest to the Trailfly Zero in underfoot feel. However, the shoe is very different in character, being wider (at least than the regular fit version of the Trailfly Zero), and more flexible. In a world of rockered trail shoes, both shoes are notably flat underfoot. Both land solidly in the middle of the range between light and heavy cushioning. Whether or not you see this as a happy ‘Goldilocks’ compromise is a matter of perspective: these are all-rounder shoes that can pretty much go anywhere and do anything. However, I feel that they are both overbuilt for daily running and underbuilt for ultradistance. Of the two, I prefer the bouncier ride of the Trailfly Zero.
Hoka Torrent 4 (RTR Review)
Dom: Hoka doesn’t have a zero-drop option. But the Torrent is the closest shoe in their line-up, with a 33/28 mm stack height, it offers moderate protection and cushioning. The Torrent is notably narrower and more rockered. It also lacks the anatomical toebox of the TFZ. At $130, it is also significantly cheaper, although durability of the Trailfly Zero is likely better.
Index to all RTR reviews: HERE
The Trailfly Zero is available at Inov8
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Tester Profile
Dom 51, trains and competes mainly on trails in Southern California. In 2017 he was 14th at Western States 100 and in 2018 finished 50th at UTMB and 32nd at the 2018 Los Angeles marathon in a time of 2:46. In 2019, his only notable finish was at the multi-day Dragon’s Back race in the UK. In 2022 Dom finished 4th in the Angeles Crest 100 and was 10th in his age group at UTMB. In 2025 Dom won the Ray Miller 50 Mile in California.
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4 comments:
Aligned with Don on preference for minimal-leaning low drop shoes but differ regarding rocker. My preference is for no rocker, so may give this new inov8 a run…
I'm going to be honest, mentioning the desire for a heel drop numerous times in a review for a shoe that is marketed as zero drop seems odd. They specifically have four models of shoe now (Zero, Speed, Standard, Max).
Interesting your findings with the heel slippage. In my wide fitting I have no problem at all, however in the TrailTalon it was so awful I had to sell them, having de-laminated the back of both heels on a long run, and I've never had that issue with any of the many pairs of Inov8s I have owned.
Thanks Don for the review. And how would you compare these to trailfly speed?
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