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inov8 Trailfly Review
By Matthew Klein 

Inov8 has been making some big changes recently. From the debut of a maximalist shoe (Ultra G 280) to some updated TPU foams, the company traditionally known for being more minimalist was clearly trying some other things. The only weird part about a more minimally/naturally inspired company is that the toe boxes were not the most anatomic and the shoes often ran on the narrow side. Beyond this company, wide-footed trail runners have always struggled given that most trail shoes tend to be narrow and snug. Outside of Altra and Topo, wide-toe box trail shoes are rare, making it challenging for wide-footed runners to find their Goldilocks fit. Two new options for them have now entered the market from Inov8. The Trailfly and Trailfly Speed both come in wide options, providing not only anatomic toe box but a ample fit throughout to accommodate those with wider feet or those who experience swelling over a variety of distances. 

INOV8 Trailfly
Price: $150 at INOV8
Weight: 9.8 oz, 280 g (men's size 9/women's size 10.5)
Stack Height: 29 mm / 23 mm
Drop: 6mm
Shoe Purpose: Moderate Stack Height Daily Training/Long Distance Trail Racing Shoe

Pros: Lightweight, nimble, anatomic toe box, flexible forefoot, great grip, durable
Cons: Narrow midfoot


The Inov8 Trailfly is an anatomic, moderate stack height trail training/long-distance race shoe for those who want a slightly firmer but bouncy ride with excellent traction and durability. The wide fit of the model is spacious throughout with a large anatomic toe box, creating a uniquely ample-fitting trail shoe for those who crave more room than the average snug trail shoe. The grip is great on a variety of surfaces from road to soft dirt while maintaining some ground feel and snappiness. While Inov8 maintains their form with a bit lower stack height than the current standard, they finally have a shoe with a anatomic toe box, fitting their natural tendencies and improving accessibility on the trail for those with wide feet. 

: Topo Terraventure 4, Saucony Peregrine 13

(To learn how a shoe should fit, check out our full podcast on fit by Matt Klein.)

The Inov8 Trailfly fits me true to size length wise in my normal men's US size 10. I received the wide fit of the model. The width is quite wide throughout the length of the shoe. I had to really tie down the laces to get a secure fit as I normal width feet. Once I got a somewhat secure fit, I was treated to a comfortable and relaxed fit. The toe box is wide and rounded, creating a rare anatomic fit for Inov8. The volume is slightly low with the toe guard, which does a great job of providing protection and a tiny bit of security. This transitions into a wider midfoot with a gusseted, moderate to thin tongue. The gusset helps with security, but I still had to really tie down the laces to secure my foot.

The heel fits normal to slightly wide and I did have to lace lock the shoe to get a secure fit. There is a thin, flexible and low heel counter that did not bother me at all. However, the low amount of heel collar cushioning may be an issue for those sensitive to stiff counters. I did not run in this shoe sockless due the already wide fit, however there are some small seams so I would suggest socks regardless of foot size. The security will be good for those with truly wide feet, but those with normal feet wanting more room should do well as long as they tie down the laces. 

Typical Size: Men's US Size 10
Shoes that have fit Matt well: Saucony Guide 17, ASICS Kayano 30, Hoka Gaviota 5, Saucony Endorphin Elite, Nike Ultrafly
Shoes that have fit snug: Hoka Arahi 7, Saucony Kinvara 14
Shoes that have fit large: Salomon S/Lab Phantasm 2, Altra Timp 5

Doctors of Running Checklist

Is This a Good Shoe for Walking: Yes
Is This a Good Shoe for Standing: Somewhat
Is the Forefoot Flexible: Somewhat
How Flexible is the Shoe: Between stiff and flexible
Is This a Good Heel Bevel: Yes but centered
Recommended for Haglunds: No
Recommended for Sockless: 
Durability Expectation: Above Average


The Inov8 Trailfly is a moderate stack height trail training shoe/long distance racer. The midsole features a POWERFLOW PRO midsole, which feels like a slightly firmer but responsive TPU material. This is combined with a META-SHANK rock plate and a beaded TPU insole. This provides a slightly firmer but responsive ride that feels protective and nimble. The Trailfly feels lighter than its listed weight thanks to the snappiness of the sole unit. There is a 6mm drop listed and it feels exactly like this. The drop is not too high or low and feels right at 5-6 mm. The heel transition is oddly smooth for having a centered heel bevel. This transitions into a quick moving midfoot and into a moderately flexible forefoot.

Even with the rock plate, which stiffens up the midfoot, the forefoot has a moderate amount of flexibility. This is not an ultra flexible ride but it is definitely not stiff enough for those with stiffness problems at the toes. However, this extra bit of flex adds a faster and more natural transition that allows a little bit of pace versatility. While the Trailfly Speed is meant for faster efforts. the Trailfly Wide still has versatility into uptempo efforts thanks to the snappy midsole, moderate stack height and a bit of kick that occurs with the META-SHANK at faster speeds. I have done a fartlek and an uptempo tempo in this and the outsole grip combined with the snappier midsole makes it easy to get a little faster. It is not the lightest and faster shoe, which combined with the midsole makes it an excellent choice for longer efforts.

While not quite stable enough in the midfoot for me over longer runs, the POWERFLOW is excellent in this shoe despite only a moderate stack height. This adds a touch of ground feel while still being protective. The outsole lugs are quite good and durable. Despite over 30 miles with plenty of road running, the outsole has remained mostly untouched. The lugs grip will on a variety of surfaces, particularly wet ones. Even partially deep mud is something this outsole can handle, while still doing surprisingly well on road. So rather than being a one trick pony, the Trailfly can handle almost any surface you throw at it as long as you are okay with a moderate midsole, slightly more snappy midsole.


The Inov8 Trailfly is a neutral shoe. There are some mild methods of guidance throughout the length of the shoe. The midfoot features decent-sized sidewalls that provide some pressure and centeredness on both sides of the foot. The forefoot is quite wide, making for an inherently stable front combined with some mild stiffness from the rock plate. The heel features a solid amount of medial and lateral sole flare (particularly medial) which provides mild resistance in both directions. The midfoot guidance is offset by how narrow the platform is at that point, making it a neutral but not unstable area. So those who want a wider platform for inherent stability at the front and some sole flare in the heel for mild centeredness will do best in the Inov8 Trailfly.

Thoughts as a DPT: Anatomic Toe Boxes and Forefoot Shock Absorption
By Matthew Klein

Trail shoes frequently have narrow fits and narrow toe boxes. While this is changing as more people request wider toe boxes due to comfort, many of these shoes were narrow to provide security with uneven terrain and for the quick reactions needed on slick/unstable terrain. While this often worked for those with narrow feet or over shorter distances, this can quickly become a problem for those with normal feet over longer distances (to accommodate swelling) and for those with wide feet. There is also a few biomechanical reasons why an anatomic toe box is better, especially on long runs and uneven terrain: the forefoot is already extremely adaptable and capable of shock absorption if appropriate motion is allowed for the toes. 

The front of your foot is made up of several bones: the metatarsals and phalanges. These have many joints that primarily move in the sagittal plane (flexion/extension) but also in the frontal (side to side) and a degree in the transverse plane. Most people know about your toes bending up and down but are less aware of the ability of your toes to spread (abduct) and narrow (adduct). This side-to-side motion, particularly the spreading of the toes, allows for shock absorption at the forefoot when the front of the foot hits the ground. Limiting it with a narrow or tapered toe box potentially inhibits this mechanism, which may not move a ton but still is important for adequate shock dispersion. The forefoot and these bones also (usually) have the ability to rotate and adapt to different angles of terrain when the toes are spread out a bit more. Although caution has to be taken as excessive twisting can cause sprains if things go too far (even up front), but the trade-off is the ability to adapt to varied terrain. 

This does not mean every single person needs a massive toe box, but Inov8's move to a more anatomic toe box in both their normal and wide versions is a great leap forward for the front of people's feet. To what degree of width is needed will depend on the unique person's feet, but a more rounded toe box is almost always a good thing. 


Neumann, D. A. (2016). Kinesiology of the Musculoskeletal System-E-Book: Kinesiology of the Musculoskeletal System-E-Book. Elsevier Health Sciences.


I have enjoyed my miles in the Trailfly. While the wide fit is a bit much for me, it is nice to see Inov8 with a more anatomic toe box. There are both wide and standard versions, which creates some great accessibility and a unique trail product for those with wider feet. My only suggestions center around the midfoot and heel. I think the midfoot is narrower than it needs to be and the geometry could be modified here to make an inherently stable ride in the center without comprising weight or ride. The heel bevel could also be positioned slightly more lateral to line up with normal heel transitions. Outside of that, this is a solid and unique option. 


The Inov8 Trailfly is a moderate stack height daily/long distance trail racing shoe for those who want a wider fit and more anatomic toe box. The anatomic fit provides plenty of toe room while a wider fit provides a good option for wide footed trail runners or those looking for a shoe that can accommodate swelling on longer efforts. The moderate stack height and slightly snappier midsole will work best for those who still want a touch of ground feel and a slightly firmer that has some pace versatility. It is a great compliment to the Trailfly Speed (review soon). The price is actually solid given the TPU-based foam, beaded insole, great grip and high durability. It has a place in the market as moderate stack height trail shoes are rare, but has common features that should make those looking for this unique fit feel right at home. 


Fit: A- (Good wide fit with anatomic toe box best for those with wider feet. Those with normal width feet will need to lock the laces down)
B+/A- (Versatile trail shoe for those who want a less maximal stacked shoe)
Stability: B [Neutral] (Wider forefoot and heel sole flare make for mild guidance in those areas. Midfoot squarely neutral due to combination of narrow width and sidewalls)
Value: A- (Good price for great versatility, grip, fit and durability)
Personal: B (I personally prefer more stack height given the longer distances I am going but appreciate the versatility onto road even if I can't take as far personally)
Overall Design: B+


INOV8 Trailfly
Price: $150 at Inov8

Shop Men | Shop Women

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Editor's Note: As always, the views presented on this website belong to myself or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your local running physical therapist. If you are in the Los Angeles, Santa Barbara, Danbury and Stevens Point areas, we am currently taking clients for running evaluations.

***Disclaimer: These shoes were provided free of charge in exchange for a review.  We thank the people at INOV8 for sending us a pair.  This in no way affected the honesty of this review. We systematically put each type of shoe through certain runs prior to review. For trainers and performance trainers, we take them on daily runs, workouts, recovery runs and a long run prior to review (often accumulating anywhere from 20-50 miles in the process). For racing flats we ensure that we have completed intervals, a tempo or steady state run as well as a warm-up and cool down in each pair prior to review. This systematic process is to ensure that we have experience with each shoe in a large variety of conditions to provide expansive and thorough reviews for the public and for companies. Our views are based on our extensive history in the footwear industry and years testing and developing footwear. If you are a footwear rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.

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