Nike drops its new race shoe out of nowhere: the ACG Kigerfly

Didn’t see it coming. And yet it’s been hiding in plain sight. Nike has just made it official: its new trail weapon is called the Nike ACG Kigerfly. Built the hard way, it was forged over months on real mountain courses by athletes from the All Conditions Racing Department. No spec sheet yet, just photos caked in mud and one certainty: just weeks before UTMB, Nike is stepping out of the shadows with a shoe that’s going to make noise. It’s already getting unanimous approval from the brand’s elites, with podiums on the biggest races in the world, from Western States to the European Championships. Here’s what we know about a model that screams speed and pure Nike DNA.

A shoe stepping out of the shadows, literally covered in mud

This time, Nike went for something more authentic by putting the athlete at the heart of the campaign (not just the product). No polished studio render, no marketing beatdown about the shoe’s benefits: instead, Nike is showing the ACG Kigerfly as-is, still smeared with dried dirt, like it’s been yanked off an athlete’s feet right after the finish. The message is loud and proud: this pair wasn’t born in a lab on a treadmill. It was shaped out on the trails, on the climbs and the descents, by Nike athletes who pushed it to the limit and fed back what mattered. The story’s great. The shoe looks even better.

According to Nike, the ACG Kigerfly has logged more than 18,000 miles (around 29,000 km) of real-world testing with members of the All Conditions Racing Department. That number is dizzying. And we know Nike doesn’t do anything by halves. For the ACG Ultrafly launch, the shoe went through 13 test cycles and more than 30,000 miles before it hit the market.

Nike unveils the ACG Kigerfly, a trail prototype tested over 18,000 miles and already winning at Western States, ahead of UTMB and a 2027 reveal.

A big debut at Western States

The best part is that the shoe was already right there in front of us. It’s already raced and proven itself at the very top of the trail world, without anyone really clocking it. Last June at the legendary Western States 100, American Jenn Lichter was wearing a hybrid prototype: an aggressive-looking shoe, somewhere between the Kiger, the Zegama and the Ultrafly. She ran in it for a big chunk of the race, then switched back into the Ultrafly 2 to finish. The result: a runaway win and a course record, on her very first 100-miler. Unreal. Right behind her, Riley Brady ran the same prototype for the entire race. Two results that already back up what this prototype can do.

Naturally, it brings back 2025, when Caleb Olson won the same race in an Ultrafly prototype, a full year before the commercial release. This time, behind Lichter and Brady, a whole crew of ACG athletes has helped shape the Kigerfly on trails around the world: Cesare Maestri, Lauren Gregory, Christian Allen, Liam Meirow, Gabriela Lasalle, Takako Takamura, and Yao Miao, three-time UTMB winner.

Still a lot of mystery around the ACG Kigerfly

Nike has shared almost no numbers. We don’t know the weight, the drop, or even the stack height. There’s also no official confirmation of a carbon plate, even though the model name “Fly” strongly suggests it (every Nike Fly model uses a carbon Flyplate). What you can clearly see in the photos, though: ZoomX foam exposed along the full length of the midsole, a slim upper with reinforcements at the toes, heel and midfoot, an ankle collar that wraps the foot well, and a structured heel for stability. Underfoot, the lugs are low and not overly aggressive, more tuned for fast, runnable trails.

Nike says the technical details will land in early 2027, which leaves plenty of time to spot the shoe across the summer’s races.

Not quite Kiger, not quite Ultrafly

The name already gives away the play: “Kiger” for the light, snappy feel of the Terra Kiger, a fast and lightweight trail shoe, and “Fly” for the speed DNA, with its carbon plate and ZoomX foam. On paper and in the photos, it really does look like a mash-up of the two: lighter and clearly slimmer than the Ultrafly, but with the same rugged, aggressive silhouette. Enough to picture a sharper, racier alternative to the ACG Ultrafly for runners chasing pure performance on technical trails, with less weight and less stack than Nike’s current benchmark racer.

Alongside the Ultrafly, which has already proved itself, Nike is adding another arrow to its quiver in the brutally competitive trail racer category. What’s interesting is the direction: a lighter, more technical product that could pair perfectly with an Ultrafly, which is more protective and a touch heavier. Now we just need to see whether the Kigerfly can go the distance on demanding trails. But between the athletes’ enthusiasm and the Western States stamp of approval, Nike looks like it’s already hit the mark.

Key info

Name : Nike ACG Kigerfly (prototype)
Development : 18,000+ miles (~29,000 km) of testing with the All Conditions Racing Department
Spotted : Western States 100, June 2026, on the feet of Jenn Lichter and Riley Brady (1st and 2nd; course record for Lichter)
Confirmed : ZoomX foam
Assumed, not confirmed : carbon Flyplate
Unknown for now : weight, drop, stack, price, release date
Next step : technical presentation planned for early 2027

This ACG Kigerfly didn’t come out of nowhere. It’s been right under our noses, on the feet of Nike athletes who’ve been forging it for months. The ACG Department athletes have been at the center of the innovation, and the way this franchise is being built makes for a great story, in classic Nike fashion. There’s still plenty of mystery around the shoe, but the podiums don’t leave much room for doubt. It already looks like the next go-to weapon for Nike ACG trail runners at the upcoming races. Starting with the “little village race” in Chamonix at the end of the month.

✔ Explore the full Nike ACG range at nike.com