Inov-8 Trailfly Ultra – 150 Miles Later

This shoe has a lot of pressure on it’s metaphorical shoulders. Inov-8 have boasted that it’s Trailfly Ultra G 300 Max has 25% better energy return than other shoes, is the first max cushioned shoe that adapts & reacts to terrain and has the world’s toughest grip. Bold claims but cutting through the buzz words and sound bites does the shoes with the world’s longest name live up to the PR hype?

Graphene has been inov-8’s innovation (pardon the pun) golden goose since 2017 when it started working with Manchester University on bringing the material to the running world. Honestly, when I first learned about Graphene back in 2010 it sounded like something out of science fiction, too good to be true. It is the thinnest material known to man at one atom thick, and also incredibly strong – about 200 times stronger than steel – and it’s applications are astounding and endless. It always sounded like something that should be wielded by Wolverine not laced up for a long run along the Thames Path. Inov-8 introduced the miracle material in it’s outsole and created it’s ultra sticky rubber that made their Terraulta G 270 so award winning. Now with the Trailfly they have enhanced the midsole foam with Graphene and this has led to the shoe being able to boast sector leading grip, durability and energy return. Too good to be true? Well after 150 miles, two ultra distance runs and a variety of terrains I can confidently say it is not just marketing gumpf. Let’s start with at the top and work our way down this lime green mile munching machine.


The upper has a racey feel to it with a thin sculptured tongue and highly breathable mesh. The mesh allows water to escape with ease so boggy environments can be bounded through with confidence. My first run out of the box was along an incredibly water logged path and despite instantly being covered in mud from ankle to crotch I was seriously impressed with how the shoe coped with expelling the water from the shoe considering the sizeable overlays. The overlays give structure and support to the shoe and the large toe bumper has been useful more times than I care to admit during the past 150 miles.

With that type of thin mesh I am always instantly weary of wear. I had a pair of Brooks Divide with a woven mesh and it lasted only 50 miles before my big and little toe had burrowed to freedom out through the upper. I did suspect that the same might happen with the Trailfly given how thin it feels but after 150 miles there is no visible signs of wear at all.

Cushion vs Speed

The max cushion, which has upset some inov-8 traditionalist will undoubtably bring new runners to the brand. Being a larger runner myself as soon as I saw these shoes at the press launch I was instantly intrigued to see how that felt on the trails, more so than any trail shoe before.

The stack is 25mm at the heel and 19mm in the forefoot giving a 6mm drop. Which makes it up their with Hoka for stack height and you can see some style inspirations that inov-8 have taken from Hoka including the slight rocker and heel kick out, which are all welcome additions from my point of view. Even though the stack height is pretty high rise I never felt like it was during my runs, even during technical sections of my ultra. The shoe very much felt like a natural shoe to run in which is the key to a good trail shoe in my books; enhances the run but doesn’t become the focus of it.

The graphene enhanced foam strikes a near perfect balance of comfort and responsiveness and even in the final miles of my 50km ultramarathon I felt the shoe had my back. When I picked up the pace I felt the jab of pace returned from the shoe akin to a raceday road shoe. Inov 8 boast a 25% greater energy return than traditional foams and while I cannot quantify the difference I have never felt energy return like it in any trail shoe before, far out classing the Brooks Catamount with that incredible DNA Flash. For my legs to feel even slightly fresh coming to the end of an ultra wasn’t surprising it was a bloody miracle! It also seems to adapt to the terrain you are on and on the road there is a noticeable kick of pace from the shoe, like it wants to play with the carbon plated boys in the class even though its just come in from eating mud with the other trail kids.

Grip and Durability

Durability is where the Trailfly becomes the stuff of legends. Most running shoes have a lifespan of about 300-400 miles, some a lot less (cough, Nike, cough). During the extensive real world tests the Trailfly was still performing at it’s best at 700-800 miles and beyond. With only a meagre 150 miles logged I can’t really back up these claims but despite being mud stained mine look and feel brand new, the outer especially show no sign of wear and I have run on both road and trail during my runs.

The grip is again where the Graphene stands head and shoulder above anything on the market. Many reviewers have echoed my sentiments so I am not alone in thinking this. I have felt nervous on steep descents thanks to absolutely stacking it during a race which made it look like I was taking part in cheese rolling rather than trail running. But in these shoes I have regained that confidence, knowing the 4mm lugs will cut through the soft ground and that graphene outer will grip on to all terrains you might throw at it.

While all that graphene is grippy and durable it is also pretty inflexible. In a trail shoe you need to have a shoe that can flex and adapt to the varied terrain you’ll be running on. So to counter that inflexibility inov-8 have come up with a simple but effective innovation, aptly called ADAPTER-FLEX (inov-8 love capitalising things!). It is a huge crevasse like cut out through the midfoot width-wise. This 10mm wedge allows the shoe to pitch and twist to cope with trails and it never felt ridged or unbalanced despite the rocky and tree root filled terrain I have run on.

The Cost of Innovation

All this innovation comes at a price and it is on both the scales and on your wallet. At 420 grams in a men’s 12 it is the heaviest trail shoe I own by a massive 100 grams. For a larger runner like me, I didn’t notice the extra weight and saw it as more cushion for pushing when the miles mount up. I do think if you were a lighter, more nimble runner then I think the weight would be a huge turn off instead looking at the more traditional inov-8 line up. Another big turn off is the price. At £170 they are the second most expensive trail shoes on the market, behind the carbon plated North Face Flight Vectiv. Inov-8 would argue that innovation comes at a cost but I would argue that while these shoes might be expensive they could last twice as long as traditional trail shoes, the maths on that pound per mile is pretty straight forward.

Final thoughts

After 150 miles, two FKTs and a 50km race I can confidently say that the Trailfly is not just a PR stunt dressed in lime green marketing, it might just be the best trail shoe ever made. But at the end of the day my words might not do much to convince you but how about the fact that I ran almost two hours faster in the 50km distance than I ever have before and I put a large part of that down to having laced up the Trailfly Ultra G 300 Max.

To learn more about the shoe and Graphene head over the inov-8’s website.

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