If you've followed , you might have noticed a shift recently. They've rebranded the entire off-road family under the (All Conditions Gear) banner. A brand once known for cool, loose-fitting clothes is now becoming the most innovative brand in the trail market, backed by Nike's financial muscle.
I got my first look at the new during UTMB in 2025, and it didn't take long to realize this was the start of a whole new direction for Nike. ACG Ultrafly is designed to be Nike's absolute top model for ultramarathon running and has unique design features developed for elite runners, which surprisingly can be easily transferred to regular runners. It gives all runners the best feeling when they hit the trails.
The technical “cheat sheet”
For all the nerds out there like me – here are the specs:
| Nike ACG Ultrafly | |
|---|---|
| Heel drop | 8.5 mm |
| Weight | Men (US 10): 287 g |
| Midsole | Dual ZoomX midsole |
| Upper | Engineered mesh |
| Outsole | Vibram megagrip |
| Plate | Split full-length carbon Flyplate |
Why does the ACG Ultrafly have a textile wrap on the forefoot?
The construction of Ultrafly is basically the running shoe's answer to a “mullet.” The hairstyle that's neat and calm in front, but has a wilder side behind (business in the front, party in the back). That's how Nike ACG Ultrafly is constructed. The original Ultrafly also came with ZoomX and a textile wrap for more structure, but a textile wrap over the entire midsole made the shoe stiff and firm. In the new Nike ACG Ultrafly, Nike has kept the ZoomX foam but done something brilliant: they've only wrapped the forefoot, making it calm and stable.
Why does it matter? When you run in technical terrain (think rocky trails in the Alps or twisted roots), you usually land on the forefoot to stay agile. The textile wrap prevents the foam from giving too much, providing you with a stable and firm platform. You can handle the steepest descents and technical root sections much easier with a firmer forefoot.
But in the heel, the ZoomX foam is raw and unprotected. This is where the wild side of the "mullet" comes out. When you charge down a hill or cruise on a flat gravel road, the uncovered heel is springy, soft, bouncy, and both saves your legs and propels you forward at the same time.
Another textile detail is the upper, which is both high-tech and simple at the same time. It's thin, breathable, and designed to drain water faster than a colander, and it doesn't change shape when it gets wet. The fit is “true to size” (I wear a US 11, and it's perfect), but for me, it felt a bit too tight at first. However, it ended up not being a problem at all; the shoe adapts to your foot, and the tightness ended up being an almost perfect fit in the end.
ACG Ultrafly will guide you to a “flow state”
Running in Nike ACG Ultrafly is like having an elite athlete on your team, mastering all disciplines in a good way. The shoe is actually, despite a high sole, surprisingly good for technical running. Although it has a firmer forefoot, it is very comfortable to wear, and despite the comfort, it can be really fast if it wants to. It's a shoe that makes it even more fun to venture out on forest trails. And either gives you the feeling of being an elite athlete or emphasizes that you are an elite athlete.
When you leave the technical forest trails and hit a gravel road, the shoe encourages you to take longer strides. You get a good “pop” from the heel, but unlike a competition shoe for asphalt, this shoe is more controlled, structured, and reliable. The split plate inside the midsole allows the shoe to twist a bit, absorbing the terrain while still pushing you forward. It makes it easier to just hit that “flow state” that most trail runners know. Where it's just you and the forest, you and the trail. The trees whiz by, and you're in a state of perfect trail harmony with a smile on your face, relaxed and fast. ACG Ultrafly is great at guiding you towards this state, so every run feels effortless, fun, and fast.
Not all runners will like having ZoomX in the midsole. It's a very lively foam, and some won't like having such a forgiving foam as the base for their shoes. If you're that type of runner, will be a versatile and stable shoe for everyday use and will be the faster and technical .
Versatile Megagrip
Just like in the first Nike Ultrafly, Nike has again chosen a Vibram Megagrip outsole. It's quite simple. Vibram is industry-leading and makes reliable outsoles that last long and grip well.
The lugs are about 3 mm deep. If you plan to wade through knee-high mud, 3 mm might not be enough – here you'll want 5 or 6 mm and a more aggressive pattern. But for 90% of all runners, 3 mm is the ideal point. Deep lugs feel like wearing football boots when you hit a hard road, but these 3 mm lugs feel great on everything from forest trails to pavements. Plus, the Litebase technology keeps the weight down (30% weight reduction compared to regular Vibram Megagrip), so you don't feel like you're running with bricks on your feet.
ACG Lava Loft jacket completes the set
You can't really talk about the “new ACG” without mentioning the Lava Loft jacket. They were released together, and they are like brown cheese and waffles. You can have one without the other, but they are best together.
Lava Loft is designed for the “in-between” weather we have so much of in Scandinavia. It's breathable, flexible, and surprisingly warm. It's the kind of jacket you put on when it's chilly, and the sun hasn't yet hit the forest floor. The best part? It's so light you don't notice it. Many running jackets feel stiff or make that “swish-swish” sound that ruins the forest's peace. This one moves with you. It's a specialist for winter and late autumn, but it's probably not ideal when the temperature goes above 10 degrees. However, it takes up no space and is easy to bring along if you're staying out overnight or just need something to take the wind on a mountaintop.
Here's why Nike ACG Ultrafly isn't just for the elite!
Nike ACG Ultrafly is the most tested Nike shoe ever. It is made in collaboration with amazing athletes who need the best of the best when they are out innature. But does that mean the ACG Ultrafly isn't really made for the average consumer? I would argue the opposite.
All trail runners need the same as an elite runner. They need a durable shoe, a stable shoe, an efficient shoe, a fun shoe, a versatile shoe, and a comfortable shoe. You get that in the Nike ACG Ultrafly. If you want something more specialized, there are other options. But looking at the overall package, you'll likely search long for something that performance-wise comes close to the Nike ACG Ultrafly.
Read more about Nike ACG's trail shoes
