Wednesday, April 17, 2024

Inov-8 Trailfly Speed Multi Tester Review: 7 Comparisons

Article by Dom Layfield and Mike Postaski

Inov-8 Trailfly Speed ($160)


Dom: In January 2024, Inov-8 took the bold step of updating the lasts on which their shoes are built, changing from a traditional ‘shoe-shaped’ last to a more modern ‘foot-shaped’ last that better reflects actual foot anatomy.  

Other prominent brands, like Altra and Topo Athletic, have always focused on a more anatomical, rather than aesthetic, shape to their shoes.  However, Inov-8 is the first brand that I’m aware of (certainly the first of any significant size) that have made such a transition long after they have established their place in the market.   This is an incredibly bold and risky strategy, as the brand risks alienating loyal customers who are upset that their favorite shoes have changed shape.

Dom: The first shoe to be released under this new strategy is the Trailfly Speed.  The shoe is available in both wide and regular variants, although both follow the new anatomical last.  This shoe follows in the footsteps of Inov8’s highly successful zero drop Trailfly G 270, which was hugely popular with RTR reviewers (RTR Review).   Before we get into the specifics of this particular shoe, the first question is ‘what is the new shape like?’

Dom: I’m delighted to report that – for my feet at least – the new last is wonderful.  It really does feel a much better match to my foot.  And it is roomy in all the right ways without compromising on foothold. 


  • New anatomically-based shoe last (shape) is excellent   [Dom, Mike P]
  • Great grip from ‘graphene-grip’ rubber outsole   [Dom, Mike P]
  • Outstanding stability and ground feel   [Dom, Mike P]
  • Beautiful shoe  [Dom]


  • With no rocker, shoe can feel flat underfoot  [Dom, Mike P]
  • Could do with a little more protection under forefoot  [Dom, Mike P]
  • On the heavy side for a stripped-down shoe with ‘Speed’ in the name.  [Dom, Mike P]
  • Heel retention adequate, not excellent  [Dom, Mike P]
  • Rides almost like a zero drop shoe [Mike P]

Please find Dom and Mike's full run bio at the end of the article after Comparisons.


Approx. Weight: men's 9.6 oz  / 272g (US9)

Samples: 10.0 oz / 284 g US M10, 9.9 oz / 280 g US M10

Stack Height: men’s 22 mm heel / 18 mm forefoot ( 4mm drop spec) 

$ 160 Available now

Most comparable shoes 

Inov-8 Trailfly G270 (Mike P)

Altra Superior 6 (Mike P)

Topo Runventure 4 (Mike P)

NNormal Kjerag (Mike P)

First Impressions

Dom:  Right out the box, my first thought was that this is a really pretty shoe.  I usually pay little attention to the appearance of a shoe, but found myself beguiled by the ‘Swedish flag’ colorway and streamlined look.  It looks both stylish and fast!  

On the foot, Inov8’s new last/shape/fit is really nice.  This feels like a shoe that is designed around a real foot, not a shoe that is shaped like the consumer expects a shoe to be shaped.  Apart from that, this is a pared-down shoe: all business, no extraneous anything.  The transparent overlays, barely visible, are minimal and functional.  The upper is smooth and uncomplicated.  Outsole is full coverage, nicely lugged.  The footbed is Inov8’s boomerang style, with TPU beads, tweaked for the new foot shape.

Footbeds from TrailFly Speed (top), in ‘wide’ variant, compared to Trailfly G 270 v2 (below).  While both employ similar TPU-beaded construction, this shows the change in shape with Inov8’s new shoe last.

Mike P: First off - the shoe looks so very simplistic, as Dom says - “pared-down”. You don’t get the sense that there are any extraneous elements around the upper, tongue, lacing areas, collars, inner liner, etc. The upper almost looks like one single element of material that wraps around the foot. Secondly, the weight of the shoe is notable, given the stripped down look and nature of the shoe. At 9.9 oz, it’s not objectively heavy, but does seem high relative to the look and feel of the shoe, as well as the low stack. Perhaps the new wider last and associated extra material bumps up the weight.

In terms of fit, I did go with the WIDE version - this time I’m properly sized in a US 10.0. That’s a half size up for me from true-to-size, but matches what I’ve always worn for Inov-8. In my “regular” Trailfly review, I noted how my sample US 9.5 was way too tight for me, hindering my testing. The Trailfly Speed feels exceptionally spacious in my US 10. I’d be curious  to try on the “regular” Trailfly in a 10 to see if it feels similarly spacious, or if it’s just a difference between models.

That being said, the wide fit is effectively Topo or Altra-esque in nature. If you’re looking for those types of footshaped toeboxes, this model definitely joins that category. Right away, I also noticed a pretty minimal feel underfoot. I’ll get to that more in the midsole/ride sections below. It gives me NNormal Kjerag vibes in terms of its minimalistic feel. Speaking of the Kjerag, the Trailfly Speed differs in that it does use an insole. The TPU beaded Boomerang insole has been updated, which I discussed in detail in my Trailfly review.


Dom:  The Trailfly Speed has a strikingly clean upper, made of a single piece of fabric with uniform weave.  The lightweight overlays (also once piece) are transparent and barely visible: notably, the whole perimeter of the shoe (rand) is fully covered, which bodes well for durability.

Dom:  The tongue is uniformly and lightly padded, with a bootie-type (connecting to the sole) gusset.  Laces are flat, and slide very smoothly through the eyelets and across the tongue, making the shoe very smooth to tighten.  Almost too smooth, in fact: the super slick laces came untied unexpectedly a couple of times.  However, I expect this to improve with time, as wear/abrasion roughens things up.

Dom:  If I had to nitpick the excellent upper, I’m not overly enthusiastic about the heel.  The heel counter is low and flexible, which I like, but above that the scalloped upper is almost like the ‘pixie heel’ found on several recent Hoka shoes.  This makes sliding into the shoe even easier, but there’s not much of a bulge at the top to hold your heel down securely.  It hasn’t proved to be a problem in testing, but might be more of an issue if I often encountered mud.  I should mention also that my heels are narrow, so likely less noticeable for most runners. 

Dom:  I also need to point out that I tested the ‘wide’ (as opposed to the also available ‘precision’) fit version of the shoe.  Plenty of width up front (I could wear toe spacers and still run comfortably).  But the heel is also probably wider than the ‘precision’ version.  I.e. shoe expanded from front to back.  This will work well for runners with generally stout feet, but is not quite as nice for people who (like me) have a wide forefoot and narrow heels.  

Mike P: Dom covers the details, so I don’t have much to add on top. I also agree with his assessment of the heel area. If you look at my closeup pic below, you’ll see that there’s not much bolstering or padding along the interior. On the interior, it just feels a bit too vertical for me - as in, it doesn’t wrap around/above the heel bone.

With that being the case, I do notice some pressure horizontally against the back of my heel. It’s almost as if the tension of the ankle lacing presses the rear of the shoe into the rear of my heel, as opposed to the more typical feeling of having the heel area of the shoe wrapping over the heel bone. I have not gotten any blisters from this, but it is a bit of a different feeling

Midsole & Platform

Dom:  Obviously, it depends on what shoes you’re used to, and what surfaces you run on, but for me – running on dry California trails – midsole thickness felt a bit meager.  Official stack height from Inov8 is 22/18 mm.  Once you account for ~6 mm of TPU-beaded footbed, ~1 mm of strobel board under the footbed, and about ~6 mm of outsole, midsole thickness must be in the ballpark of 9/5 mm.  

I had no issue with the heel cushioning, but I felt rocks pretty sharply through the sole in the forefoot.  A couple more mm of midsole would be appreciated.  The outgoing (and much-lauded) Trailfly G 270 has 22 mm (zero drop) overall stack, with 12 mm of midsole, and personally, I find this a more comfortable thickness.  YMMV.

Dom:  Otherwise, the shoe is a delight to run in.  The relatively thin midsole and low stack height means that ground feel is excellent and stability is impeccable.  

Mike P: Along with the upper, the midsole has quite a minimal feel to it. Dom breaks down the different elements, and yes, it does feel pretty thin, particularly under the forefoot. With the wide, spacious forefoot, and the minimal stack, you definitely get a lot of ground feel, which is something to be aware of, and something you may in fact be looking for.

One shoe that immediately comes to mind is the Altra Superior, with a similar thin midsole, but of course zero drop. That’s just to give you an idea of the type of cushion that you’re working with here. There’s a big gap in cushion level between this model and the regular Trailfly model. Inov-8 did well to stay on opposite ends of the spectrum with the two new models, and not overlap too much. 

The regular Trailfly is listed at 29/23mm compared to 22/28mm here. That’s a massive difference, not just numbers-wise, but also in actual feel. 

The regular Trailfly’s forefoot cushion is much more substantial, and the heel cushion is also much softer. In the regular Trailfly, I noticed a “crash-pad”-like feeling at the lateral heel which absorbed impact much more comfortably during descents. The Speed version has no such “crash pad” and is much firmer under the heel. You’ll really want to keep your landings balanced in these.


Dom:  I’ve previously been somewhat underwhelmed by Inov8’s ‘graphene enhanced’ outsole rubber formulations.  The tech has always felt overhyped.  My own experience has been that grip is good, but not outstanding.  Similarly, durability has been good, but not stellar – and the gritty dry trails in Los Angeles tend to wear down outsoles quickly.   

Dom:  Is it my imagination, or have Inov8 improved the rubber?  I found the outsole traction of the Trailfly Speed was strikingly good.  On steep, sandy descents that are often hazardous in less grippy shoes, the Trailflys felt totally surefooted, giving me confidence to run at breakneck pace.

Mike P: Maybe I’ve been part of the hype train, but I’ve found Inov-8’s outsoles to be very good in my experience. Durability is definitely on the high side. I’ve found that Inov-8’s midsoles seemed to deaden long before the outsoles wore out. Dry traction is excellent, but I’ve found wet traction to be just ok - not as good as VJs or Vibram Megagrip.

I mentioned the Altra Superior as a comp earlier in the midsole section, but in terms of outsole, this is where the Trailfly Speed differentiates itself. It’s also an area where weight is likely added in comparison to other lightweight shoes. With full coverage upper, Inov-8 really wants to ensure that you get full grip and traction on top of so much ground feel.

The outsole works well, traction is excellent in the mostly dry terrain that I’ve been able to test. The Meta-flex groove spanning the ball of the foot allows the forefoot to flex freely. Typically, full coverage rubber adds a level of protection, but it’s not evident here with such a minimal stack. You still feel rocks pushing through and the shoe generally is not very protective. The outsole does not get in the way of ground feel.


Dom:  Is the ‘Speed’ in the name a misnomer?  After recently testing several carbon-plated trail shoes, the Trailfly Speed felt a little undersprung on pavement.  It is also lacking the rocker that has become prevalent in many shoes, and feels somewhat flat under the midfoot.  It’s not very competitive in terms of weight, either.  So: not really a race shoe.

The flipside is that this shoe is a beast on technical terrain: the combination of excellent grip, low stack height, and no secret doodads complexifying the ride results in a shoe that bounds from rock to rock with uncanny ability.

The low (4 mm) drop was not really noticeable for me.  I found it almost indistinguishable from a zero-drop shoe – in a good way.  But if you struggle with zero-drop shoes, you might find those few millimeters make all the difference.  I’m happy either way, but generally dislike trail shoes with high heel-to-toe drops.

Conclusions and Recommendations

DomSome shoes ultimately feel less than the sum of their parts: Despite having no egregious failings, they don’t excel anywhere and lack character.  Not so here: The Trailfly Speed is an instant classic.  Not only does it look splendid, but it is a tiger in technical terrain.  Inov8’s new foot shape is a huge win from my perspective: My feet are happier, with no apparent downside.

Dom:  Despite its name, I’m not clear that I would wear the Trailfly Speed to race.  It feels under cushioned for ultras and for shorter distance races, there are shoes where I would trade comfort and/or grip in exchange for a much lighter weight (e.g. Salomon Pulsar, Hoka Zinal 2).  It also might lose out to carbon-plated supershoes.  But I don’t think that matters:  The TrailFly Speed is just such a pleasure to run in that I already choose it as my daily training shoe.

Dom:  To be clear, this is not for everyone.  Compared to most trail shoes (particularly the ones that are popular in the US), the Trailfly Speed is unusually soft and lightly cushioned, with a distinctly minimal feel to it.  But I enjoyed its idiosyncratic character.  Like driving a small convertible like the Mazda Miata (MX-5 overseas) or BMW Z3, there’s no rational argument that this shoe makes sense or is quantitatively better than mainstream choices.  It’s just fun and beautiful.  And for some of us, that’s all that matters.

Mike P: Dom pretty much sums up everything that I think about the Trailfly speed.. exactly. It’s not quite a race shoe, there’s not quite enough cushion for longer distances, yet it doesn’t feel dynamic enough as a short distance racer. I also concur with his opinion that it really does ride like a zero drop shoe. Probably the combination of low stack, and non-rocker geometry makes it feel that way. 

I do feel a bit of tension along the insides of my heels around the Achilles insertion area. It’s just one of those little bits of tightness that can show up when running in zero drop shoes. Typically I find 4-6mm drop to be the sweet spot for trail running, but these ride as if they’re in the range of 0-2mm. Yes, they are listed at 4mm, but Dom and I both got somewhat similar impressions about the drop.

Dom also appears to love them in technical terrain, and I think that’s because he has a wider foot than me. Differences in foot size really can make a difference in how a shoe feels - especially in terms of security if your foot really sizes well inside a shoe. For me, the wide fit is a bit too spacious for me, so I don’t have the same level of confidence in technical terrain. There’s just a touch too much space for me and too much movement to trust them at high speeds.

Going back to the regular Trailfly RTR Review, it does seem like these are relatively wider up front. I’d be better suited with the standard fit in these. If you don’t necessarily need the wide forefoot, I’d recommend going with the standard. If, like Dom, you like that amount of space, it’s a great option to have.

Mike P’s Score:  8.13 / 10

Ride: 7.5 - Great in terms of ground feel, but other than that, pretty minimal. I prefer the added cusion of the regular Trailfly model

Fit: 8 - Completely subjective, probably would have been better off with the standard fit personally. The heel area needs to be bolstered a bit and perhaps some comfort added.

Value: 8 - This again is highly subjective. But it’s not a racing shoe, not a shoe for long days

Style: 9 - It’s eye catching

Traction: 9.5 - Really great, enhanced by ground feel

Rock Protection: 8 - You’ll need to dance to avoid rock hits

Smiles 😊😊😊

7 Comparisons

Index to all RTR reviews: HERE

Inov-8 Trailfly  RTR Review

Mike P (10.0): *Note I’m listing my appropriate size here even though I tested a too-small 9.5* Detailed comparison is found throughout this review - the Speed flavor is much more minimal - thinner underfoot, more flexible, and rides somewhat like a zero drop shoe. It features a very wide toebox - noticeably wider than my sample Trailfly (Wide version, US 9.5). I’m not sure how different that would be if I had a proper for me US 10.0, but there’s a lot of space here. The Trailfly Speed seems to run wider. If you’re looking for something that’s closer to the G 270, go with the regular Trailfly. If you want/need toebox space, minimal cushion and enhanced ground feel, go with the Speed

Inov8 Trailfly G 270 v2 (RTR Review)

Although the Trailfly Speed continues the “Trailfly” branding, the two shoes have little in common.  In addition to the new “foot-shaped” last, the Trailfly Speed is a complete redesign, with different materials, construction, fit and feel.  They both share the always excellent “boomerang” TPU-beaded midsole, which provides bounce and long-lasting resilience without absorbing moisture.  Trailfly Speed, however, is lower stack, with less cushioning.  It also has full-coverage outsole, with improved grip.  

Outsole comparison between new TrailFly Speed (top) and outgoing Trailfly G 270 v2.

Trailfly Speed also has 4 mm of drop, which may make it more appealing to runners who were deterred by zero-drop of outgoing 270.  Personally, I really enjoy both shoes.  I prefer the shape of the new Speed, but enjoy the extra forefoot cushioning of the 270, particularly for longer runs.

Mike P (10.0): The original G 270 was a great shoe for me, and I put lots of miles into them. This Speed version feels a bit too minimal underfoot for me to rack up that many miles in them. I do think the wider upper is more comfortable - I don’t get any big toe side or pinky side rubbing as I did at times with the G270. But I also don’t feel as secure in the wide fit Speed model. Perhaps the standard fit would be better for me. The G270 is clearly more comparable to the new “regular” Trailfly model.

Hoka Zinal 2 (RTR Review)

Dom: Given the name, I hoped the Trailfly Speed might be a worthy competitor to Hoka’s fast-and-light race-oriented trail shoe, the Zinal 2.  The Zinal, at 30/25 is higher, but on the foot, the two feel similar in terms of stack and cushioning.  The Inov8 definitely has better grip, and I far prefer the shape.   But the Zinal 2 is dramatically lighter 215 g vs 284 g (7.6 oz vs 10 oz) than Trailfly Speed (in size US M10).  So on race day, it's not even close.  The Speed is more appropriate for everyday running.

Altra Superior 6 (RTR Review)

Dom: The lightest trail shoe from Altra, the Superior has 21 mm zero-drop stack, compared to 22/18 for Trailfly Speed.  Weight is pretty much the same (both around 10 oz for US M10).  

I wanted the Trailfly Speed to have a little more midsole in the forefoot, and preferred the slightly better rock protection provided by the Superior.  Both are really excellent daily training shoes, but neither would be my pick to race (over any distance).  

Both are very comfortable shoes, particularly for runners liking a wider forefoot.  

The Trailfly does have better grip, but it’s worth noting that Altra’s historically mediocre ‘MaxTrac’ outsole rubber has recently been significantly upgraded, so this is no longer a weak point for Altra.  The choice here mostly comes down to whether you want zero-drop or low-drop.  I will say, however, that the Trailfly Speed clearly has the edge in looks!

Mike P (9.5): I’m a big fan of the Superior 6 - for me it’s the best Superior version. It has a bit snugger fit up front than the Wide fit Speed model. It fits my footshape just right, where as there’s a bit too much space in the TF speed. Both outsoles are comparable, but the Inov-8 will surely be more durable. While still minimal, the Superior’s midsole feels like a bit “more” underfoot than the Speed. Even though the Superior is zero drop, for some reason I feel a bit more strain around the Achilles with the TF Speed. Maybe something about the contouring of the cushion underfoot - it also hugs the bottom of my foot perfectly. My pick is the Superior 6.

Topo Runventure 4 (RTR Review)

Dom: The Runventure is the most minimal shoe in Topo’s tail line-up, with 20 mm of stack and zero drop.  A very similar shoe to the Trailfly Speed in many ways: similar weight, similar stack height, full-coverage outsole, even a similar last.  I didn’t get to test v4 of the Runventure, but really enjoyed previous versions as near-minimal everyday training shoes.  

The Runventure rides a little firmer and provides more protection in the forefoot.  The Trailfly is slightly softer and bouncier (probably due to TPU-beaded footbed).   

Both are excellent shoes, albeit with too little cushioning for truly mainstream appeal.  But if you feel that most trail shoes are overbuilt behemoths, you can’t go wrong either way.  That said, it looks like Topo are phasing out the Runventure 4, so you may only have one option in the future.

Mike P (9.5): This shoe feels really close to the TF Speed. Full coverage outsole with minimal stack, but shoes can feel a bit thin under the forefoot as the miles wear on. The Topo for me fits more securely, and the upper is more comfortable, especially the heel area. I really dislike the Topo Ortholite insoles though, so big edge to the new Boomerang insole in the TF Speed. I’d call it a pick-em between the two, with the tie-breaker actually being the Inov-8 insole as you can use it in other shoes.

Topo MT-5 (RTR Review)

Dom: The MT-5 has 28/23 stack height, so slightly more than Trailfly Speed.  Its ‘anatomical’ shape is very much like Inov8’s new last, and both are sublimely comfortable on my foot.  Both are soft and flexible.  MT-5 is more of a road-to-trail shoe, so feels slightly more at home on pavement.  On trail, the Trailfly Speed’s excellent full-coverage outsole has much better grip. MT-5 is slightly lighter, but the difference is insignificant for training or casual running. 

Salomon S/Lab Pulsar (RTR Review)

Dom: The Pulsar exploded out of nowhere a couple of years ago, being lighter by far, than anything on the market.  It remains a high water mark for how light a trail shoe can be.  But the fit is narrow and slightly strange, and the shoe feels flimsy.  The Pulsar, astonishingly, has more stack height (27/21 vs 22/18 for Trailfly Speed), but doesn’t provide more protection.  The Trailfly Speed is a much nicer shoe to run in, having better grip and comfort.

Mike P (9.5): Pulsar is the pinnacle of ultra-lightweight trail racing shoes. I don’t think there’s been anything even close to it in terms of weight. Sure, the fit is super snug, an with the platform a  bit narrow, but it allows Salomon to pack in a bit more stack, some dynamic rocker, with the low weight allowing the runner to be nimble and handle them. It’s definitely not a training shoe, but a racer for many distances (I’ve run a 50 miler in them). 

NNormal Kjerag (RTR Review)

Mike P (9.5): This shoe popped into my head right away due to its similar and surprising minimal feel under the forefoot. The Kjerag uses a supercritical foam though, and its ride does feel more dynamic. Its 6mm drop is also more comfortable and suitable for a wide variety of speeds and distances. In terms of fit - Kjerag has a similar level of wide forefoot space, but the laces extend a bit lower and I feel like I can get a much better fit with them. It has no insole either, so feel is different, but that does eliminate any foot movement. For me, the Kjerag is a more versatile shoe, although you pay a bit more for that versatility.

The Trailfly Speed is available now

Inov-8 HERE

Amazon HERE

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.

Mike Postaski currently focuses on long mountainous ultras - anywhere from 50K up to his favorite - 100M. 5'10", 138 lbs, midfoot/forefoot striker - he typically averages 70 mpw (mostly on trails), ramping up to 100+ mpw during race buildups. A recent 2:39 road marathoner, his easy running pace ranges from 7:30 - 9:00/mi. From 2022-23 Mike has won the Standhope 100M, IMTUF 100M, and Scout Mountain 100M trail ultras. He also set a CR of 123.74M at the Pulse Endurance Runs 24H and completed the Boise Trails Challenge on foot in 3 days 13 hours, besting the previous record by 7 hours. Mike's shoe preferences lean towards firmer, dense cushioning, and shoes with narrower profiles. He prefers extra forefoot space, especially for long ultras, and he strongly dislikes pointy toe boxes.

Samples were provided at no charge for review purposes. RoadTrail Run has affiliate partnerships and may earn commission on products purchased via shopping links in this article. These partnerships do not influence our editorial content. The opinions herein are entirely the authors'.

Comments and Questions Welcome Below! Please let us know mileage, paces, race distances, and current preferred shoes

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Anonymous said...

I've seen no mention anywhere for these new Inov8 shoes on what the PF Pro midsole is actually made of and the characteristics? Any ideas?

Anonymous said...

I asked them it's just a slab of cheap eva

Mike P said...

We were provided spec sheets by Inov-8 for both Trailfly versions - there are no details about the foam composition.