Inov-8 TrailFly Speed Review

It’s time to sum up a bunch of miles off-road in our Inov-8 TrailFly Speed review. The Inov-8 TrailFly Speed is the latest addition to the range of new Inov-8 running shoes that are focussed on providing a more anatomical shape to the last and cushioning levels that allow for foot function. The TrailFly ‘Speed’ is designed to be used on hard-packed trails and unlike the regular TrailFly, has been stripped back to provide a good level of ground feel and flexibility that allows your feet and lower legs to propel you over the ground at a quicker speed than shoes that have less flex and more underfoot protection.

More Roomy Fit

The anatomical foot shape to the last is the same as that used for the Inov-8 Mudtalon and Inov-8 Mudtalon Speed. This has a snug fitting heel, a good fit through the midfoot and then the upper opens out into a broader rounded toe box. The upper is designed to hold the foot onto the midsole even when running on a camber or over rough, uneven terrain, but at the same time have enough room in the forefoot for the foot to spread on impact. This allows your feet to function inside the shoes, keeping you more nimble and able to negotiate tricky terrain. It’s a lot easier to maneuver than in a stiff, restrictive, or softly cushioned running shoe.

When your foot hits the floor midfoot first, your foot spreads out as nature intended. This stretches the planta fascia on the base of your foot, which cushions then recoils to spring you into your next step. This natural foot function only happens if you land on your midfoot and is further enhanced if there’s room in the shoes to allow your feet to expand. The other advantage of your feet being able to function inside the shoes is that you have much better balance. It helps tremendously on rough trails when you are skipping over obstacles and negotiating various cambers.

The heel fit is better than the heel fit in the Mudtalon and Mudtalon Speed, which although it held my heel fine, felt somewhat loose which cast some doubt about slippage on steep climbs etc. The TrailFly Speed fits lovely and snug around the heel and through the midfoot.

Currently the TrailFly Speed is only available in a wide fit option, yet isn’t super-wide. If you are used to wearing roomier running shoes, maybe even Altra’s or Topo Athletic running shoes then this won’t feel unusual. If you are used to the old Precision Fit last Inov-8 shoes, which were very snug, then the TrailFly Speed is going to feel roomy. If you have the widest of feet, give them a go, but you might end up swapping for something even wider because it’s got a snug and secure midfoot, the same as the Inov-8 Mudtalon and Inov-8 Mudtalon Speed in wide fit. At the end of the day, they need to be snug enough to hold the foot at the heel and through the midfoot to avoid slipping on camber and descents. It’s a tricky balance to nail!

BROWSE INOV-8 TRAILFLY SPEED RANGE

Upper, Heel & Tongue

The upper is made from a single piece of air mesh material to minimise seams. The heel has a half plastic cup to give it some structure but is still very flexible. When you lace the shoes up the heel cup pulls in around you and is capable of taking the shape of your heel. The heel cup and heel are lightly padded with a very soft material. The tongue has a good level of padding and is gusseted all the way up to almost the top of the laces, to help prevent debris getting inside. The laces thread through a tab on the tongue to help prevent the tongue from moving while running. There is an additional lace hole should you wish to butterfly lace the shoes for a snugger fit. The laces themselves are very thin and do tend to come untied unless you double knot them and pull them tight.

On the outside of the mesh upper is an overlay that runs around the base of the shoe to protect the upper from abrasion. This opens out in the toe to create a semi-stiffened toe bumper and big toe guard. The lace eyelets are reinforced with overlays. Tapes come down from these overlays and attach at the base of the upper. These tapes are what pulls the upper in around your midfoot when you lace up.

I found the fit very comfortable and akin to the Inov-8 TrailFly G270 which was 0mm drop. Plenty of room for my toes to wiggle just like in an Altra or Topo Athletic running shoe and real natural feel when running in them because of the flexibility in the midsole.

Cushion

The insole is Inov-8’s high energy returning Boomerang insole, a 6mm thick nitrogen infused insole that essentially means that the air bubbles in the insole have been sealed. When you land on the insole, as the air can’t escape, you get sprung back with a lot more energy. It gives a slight bounce to the feel of the shoes and as the insole is only 6mm thick, there isn’t any noticeable compression and it doesn’t take away your awareness of the ground. Your foot still ‘knows’ it has touched the floor and functions well inside the shoes.

The midsole is made from Inov-8’s Powerflow Pro, which is cushioned yet responsive foam designed to absorb shock without too much compression so you can still be light and nimble on your feet. Below the midsole is a very flexible rockplate. This is designed to protect the foot from thorns or sharp rocks that might pierce the shoes and bruise your feet. The midsole is 11mm thick in the heel and 7mm thick in the forefoot, which in this day and age of oversized midsoles, seems thin. However, with a 6mm thick insole and a rubber outsole this gives a total stack height of 22mm or so in the heel. The effectiveness of the insole means that they don’t feel hard on impact.

Graphene ‘G-Grip’

The sticky rubber outsole has been Graphene-infused to increase the durability and the stretch and flex of the rubber. Inov-8 claim that the rubber used is stickier than the one previously used on TrailFly models. It’s hard to test this as the TrailFly Speed is so flexible that is moulds to the shape of the ground much more effectively than other Inov-8 running shoes. This means that there is more rubber in contact with the surface you are running on, which gives you better traction. What I can say is that it has been very wet for the few months I have been running my review miles in the TrailFly Speed and I haven’t questioned the grip on anything but really soft, sticky muddy ground. After all, the shoes aren’t designed for the worst mud and the 4mm lug isn’t designed for that terrain. On silt covered hard packed trails, which are slippery in other trail shoes at the moment, there hasn’t been an issue in the Inov-8 TrailFly Speed.

No Rocker, Carbon Plate or Jet Pack?

The 4mm heel to forefoot drop, broad rounded toe box, good level of ground feel and high level of flexibility makes the Inov-8 TrailFly Speed a very natural ride. In the current climate, so many running shoes are built to do some of the work for you. Inov-8 have taken a different view, and avoided all the technology that prevents your feet from functioning. You can get that extra bit of propulsion from your feet working as nature intended. This suits trail running in the UK, where we are lucky enough to be able to get onto unsurfaced trails and run freely over the countryside. For shoes with carbon plates or super critical foams, you need a hard and even surface for them to work and return that energy. Trail running tends not to provide this hard even surface continuously.

The buzz that you get from trail running is from exploring the trails that have more broken ground. The single tracks through the woods or down by the river. The Inov-8 TrailFly Speed is a great option for this type of running. The midsole flexes in all directions, so even on the trickiest ground or the most rutted you can still make forward progress without worrying about the shoe flipping you over and twisting an ankle.

If you aren’t used to running in shoes that allow your feet to function, then it’s a good idea to gradually increase the time you spend in the shoes, alternating with your current shoes. This will allow your feet, ankles, and lower legs the chance to get used to functioning and get stronger without getting overloaded.

—

Rather than supply a weight for an individual size e.g. UK8, Inov-8 state an average for each of their shoes across the size run. The average weight of the Inov-8 TrailFly Speed is 270g.

Inov-8’s are similar in length to Hoka, New Balance, La Sportiva and Karhu. Try half a size larger in Inov-8 to get a similar length to something like Brooks, Saucony, NNormal, Topo Athletic or Altra.

Summary

I have had the Inov-8 TrailFly Speed in my running shoe review rotation for a few months. They have done all types of running, from speed work on a wet cinder track, to 2-hour-plus long runs on mixed terrain. Over short parts on the tarmac I found them cushioned enough, but the outsole does slap a little bit and make a little bit of a noise, similar to VJ Shoes. Once off the road, none of these things are noticeable and they ride great. I haven’t been running in this type of shoe recently, as most shoes that I get to review have rockers. The feeling with a rocker is of ‘riding the shoes’, rather than running, as the rocker guides your legs back. It therefore took me a few runs to get used to running in the TrailFly Speed.  Once I did, I really enjoyed the feel of more natural speed and the ease that you can run over rutted grass fields or dive down steep descents. I could feel that I was working my glutes and hamstrings more than normal, particularly on longer runs, because you’re really running.

The Inov-8 TrailFly Speed is a very flexible, natural feeling trail shoe designed for firmer tracks and trails.

Other Considerations

VJ Lightspeed: VJ like Inov-8 make trail shoes not road shoes in disguise. The Lightspeed has a similar feel for the ground and a sticky durable rubber outsole. The grip isn’t quite as good on greasy single track. The lugs are slightly shorter and just don’t bite quite as well. There is a plastic plate to give some propulsion. This doesn’t have much effect on soft ground but does push you a long a bit on firmer, smoother tracks. The last shape has a straight big toe line but isn’t as anatomical as the TrailFly last.
https://www.northernrunner.com/blog/vj-sport-lightspeed-review/

VJ MAXx2: These have a similar level of traction. Less ground feel but little more bounce. The Maxx 2 is stiffer than the TrailFly Speed, so you don’t get the natural feel to the ride and the shoe isn’t as flexible, so it doesn’t take the curvature of the ground as easily. https://www.northernrunner.com/blog/vj-sport-maxx2-review/

Altra Mont Blanc Carbon: A very flexible shoe for a carbon shoe. The toe box is rounded to not as broad and roomy as the TrailFly. There is a lot more cushioning which gives a lot softer ride but takes away from the ground feel and doesn’t stimulate foot function as well. The traction isn’t as good once you step off dry hard packed tracks.
https://www.northernrunner.com/blog/altra-mont-blanc-carbon-review/

Altra Lone Peak 8: Similar fit and feel a little stiffer and a little less forgiving on the harder ground. Mainly due to not having the Boomerang insole that the TrailFly has. The grip of the TrailFly is better on softer ground. https://www.northernrunner.com/blog/altra-lone-peak-8-review/

Brooks Catamount 3: The forefoot plate that is in the Catamount take away the ground feel and makes the shoes feel less nimble. They cruise well on dry, hard packed trails. https://www.northernrunner.com/blog/brooks-catamount-3-review/

Topo Athletic Pursuit: A zero drop shoe with a good level of responsive cushioning. The grip level is similar as is the width. The pursuit doesn’t have quite the same natural feel as it is slightly stiffer shoe like the Altra Lone Peak. https://www.northernrunner.com/blog/topo-athletic-pursuit-review/

Altra Superior 6: The cushioning level and flexibility is similar to the TrailFly Speed. Although the Superior doesn’t have the same level of traction on anything but hard packed trails. It also feels less cushioned as it doesn’t have the Boomerang insole. https://www.northernrunner.com/blog/altra-superior-6-review/

Hoka Tecton x2: A carbon plated shoe that is much stiffer with a lot less ground feel and traction. On hard dry, hard packed trails the carbon plate would provide some propulsion but get off the forest roads and they aren’t flexible enough with enough ground feel to flow over the ground as effectively as the TrailFly Speed. https://www.northernrunner.com/blog/hoka-tecton-x-2-review/

NNormal Kjerag: Designed to be used on everything from short trail events to 100 miles the Kjerag does have more cushion than the TrailFly Speed. However, it is stiffer and doesn’t have the same ground feel or traction.

Scott Supertrac RC 2: A similar nimble shoe. The 6mm lugs gives the shoe more traction on softer ground yet it rides well on hard packed tracks and trails. The ride isn’t as natural and there is less foot function as the last is narrower and there is a rocker in the shoes. https://www.northernrunner.com/blog/scott-supertrac-rc-2-0-review-trail-fell-running-shoes/

Hoka Speedgoat 5: A much softer feel to the cushioning and a rocker. There is very little ground feel and the rocker takes over the gait cycle so you aren’t as nimble. https://www.northernrunner.com/blog/hoka-speedgoat-5-gtx-review/