inov-8 TrailFly Ultra G 300 review: durable trail shoes for hard surfaces

Tear up the trails in inov-8’s most cushioned and flexible shoe so far, the inov-8 TrailFly Ultra G

inov-8 TrailFly Ultra G 300 side view
(Image credit: Future)
Fit&Well Verdict

If you’re looking for a pair of trail shoes that will tackle most types of trails and take you comfortably along paved surfaces, the TrailFly Ultra G 300s will see you through both.

Reasons to buy
  • +

    Ideal for those running on a mix of trail and roads

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    Perfect if you want to feel closer to the trails

  • +

    Protective and breathable

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Reasons to avoid
  • -

    Slightly bulkier and wider than you may be used to

  • -

    Not designed for mud and gravel

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    At the higher end of the price range

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Find out all you need to know in this inov-8 TrailFly Ultra G review as we explain how the brand’s latest shoes performed.

Trail running experts inov-8 are constantly exploring new ways to push off-road running shoe technology forward. Based in England’s Lake District, the brand makes some of the best trail running shoes around as they know the hills like few others: with swathes of fells and England’s highest points surrounding them, they can test prototypes on some of the most challenging terrain on the planet. 

In 2018, inov-8 released the first groundbreaking shoe to feature a Graphene sole. The innovative Graphene material is created from graphite, and is renowned for its strength.

What this means for your running is that you’ll experience increased bounce and flexibility combined with never-before-seen durability and grip, so the sole will effectively never wear down, meaning you can run more miles before having to replace the shoes.

The company’s latest release, the TrailFly Ultra G 300, is the first to feature inov-8’s new Graphene-enhanced G-FLY foam (as well as the Graphene sole), which inov-8 says lasts longer without compressing the foam while providing 25% more energy return.

inov-8 TrailFly Ultra G 300 sole

(Image credit: Future)

inov-8 TrailFly Ultra G 300 review: price & features 

The inov-8 TrailFly Ultra G 300s retail for $190/£170(men’s and women’s). There is only one color available – neon green and black.

I tested the men’s shoe in UK size 11.5 by running on a variety of road and off-road terrain, including sand, hard-packed trails, wet mud, gravel, stones, and asphalt.

The heel-to-toe drop is 6mm, the lug depth is 4mm and both the men’s and women’s shoes weigh 300g but the main selling point is the fact that it’s the first shoe to feature Graphene-enhanced foam soles, designed to provide 25% greater energy return than widely used EVA foam, according to inov-8. The other innovative feature is the Adapter-Flex groove across the sole, engineered to bend when the terrain demands instant reaction and flexion.

inov-8 TrailFly Ultra G 300 review: design & technology 

The headline news on the inov-8 TrailFly Ultra G 300’s design front is the aforementioned Graphene foam, which is claimed to provide increased flexibility, cushioning, and longevity. This is combined with the shoe’s groundbreaking Adapter-Flex groove that splits the sole in half. Acting like a hinge, the idea is the front of the foot can bend independently to the rear, providing added flex and adaptability over technical trails. 

The idea with the TrailFlys is that they bring you closer to the trails, so even though the sole appears to be thick, they’re not hugely cushioned compared to other trainers available on the market. The brand has a reputation for creating shoes that bring you closer to the trails, so expect to feel bigger rocks and roots through the sole, meaning you can react rather than floating along on a pillow of foam. That feeling might not suit every runner, but I enjoyed the feeling of that connection to the trails which can be missing with some shoes.

inov-8 TrailFly Ultra G 300 trainer print

(Image credit: Future)

inov-8 TrailFly Ultra G 300 review: fit, feel & comfort 

The fit is snug and tighter than average – I’d recommend going at least half a size up from your regular size as they come up small, and that way you also have room for swelling when you run long distances.

The tongue is built of thin material and unpadded to reduce weight, in keeping with many other shoes. This means you can feel the laces if you do them up too tight. 

The breathable upper worked well – my feet never felt too hot during test runs, although I wasn’t running in peak summer heat. The toe box is designed to be wide to give your feet room, and it is also protected around the toe area to protect you when you whack your foot on protruding rocks.

inov-8 TrailFly Ultra G 300 review: support 

Support is as good as it gets – this is inov-8’s most cushioned shoe, meaning your feet will feel fresher for longer. The Adapter-Flex groove is a nifty addition, making the entire running experience feel a little less rigid. 

The unusual Boomerang insole also contains compressed beads underneath that spring back for a claimed 40% extra energy return. I can’t say that I noticed the beads at work, but it’s good to know they are working hard in tandem with you.

inov-8 TrailFly Ultra G 300

(Image credit: Future)

inov-8 TrailFly Ultra G 300 review: performance 

On testing, the shoes gripped well on harder trails with little to no slippage except on ultra-steep climbs on a gravel and pebbly surface. During my longest test run of 15km, they remained comfortable and tackled muddy terrain well. They felt light on the feet and a little clunky at first due to the wider soles (especially at the front), but I soon got used to that.

On asphalt, they are well-cushioned and you can feel the energy return from the Graphene soles. I have no doubt these shoes will last years of happy trail running. 

inov-8 TrailFly Ultra G 300 review: verdict 

In terms of sustainability, the inov-8 TrailFly Ultra G 300s do more miles than average as the Graphene sole and foam is designed to last longer, so you won’t need to replace your trainers as often. These shoes are also great for running on a variety of terrains and you'll also feel the ground beneath you. If you're looking for a budget pick, however, these are not your cheapest option and they are quite bulky.

Also consider

On CloudUltra

On Cloudultra trail running shoes shot from the site

(Image credit: Howard Calvert)

The On CloudUltra shoes are designed to take you seamlessly from the road into the wilderness. On CloudUltras also feature superb grip and a double layer of cushioning designed to help you run for longer.

Hoka Speedgoat 4

Hoka Speedgoat 4 shoes

(Image credit: Hoka)

The Hoka Speedgoat 4s put cushioning and grip at front and center but they also perform well on the roads if you’re running on mixed terrain. They really come into their own off-road, with advanced levels of grip and support, meaning you can tackle the most technical of trails with confidence. 

adidas Terrex Two Primeblue

Adidas Terrex

(Image credit: adidas)

The adidas Terrex Two Primeblue are designed to be lightweight and grip well on any surface. The Primeknit mesh upper fits to the foot snugly in a sock-like manner, while letting them breathe. The upper is also partly built from Parley Ocean Plastic, which is upcycled waste from the sea.

Howard Calvert

Howard is a freelance health and fitness journalist and copywriter. He has written for publications including ShortList, Runner’s World, Trail Running, Women’s Running, Red Bulletin, Wareable and Cycling Weekly. He enjoys nothing more than lacing up his trail shoes and heading out to explore new trails. He’s run ultramarathons everywhere from the French Alps and Canadian mountains to the Welsh coast and Peak District. When not running, he’s usually found hitting his local MTB singletrack trails or on a quest to find the country’s best cinnamon bun.