After 30,000 miles of testing and 13 rounds of prototyping, Nike’s second swing at a trail super shoe fixes everything wrong with the original while doubling down on what worked. Now placed in the brand’s outdoor-focused ACG line, the Ultrafly is a complete reimagining of how carbon-plated technology translates to unpredictable terrain.
A Carbon Plate That Actually Cooperates
Where the original Ultrafly felt like a road shoe masquerading as a trail runner, this new iteration embraces the unpredictability of off-road racing. The first version had an incredibly-stiff full-length carbon FlyPlate. This was great for road racing efficiency but less ideal when you’re navigating trail hazards. Nike’s solution here is elegantly simple: they split the plate down the spine and reduced its rigidity. The result is a 7/8-length plate that flexes with terrain rather than fighting it.
The original plate required significant force to compress, limiting its effectiveness for anyone under a certain weight threshold. The redesigned version democratizes the super shoe experience across body types.
ZoomX Gets an Upgrade
Nike’s signature foam returns in dual-density configuration, though they’re keeping the exact setup under wraps. Based on the lateral segmentation visible on the midsole, expect a firmer carrier foam below the plate with softer ZoomX directly underfoot. The addition of a ZoomX sockliner adds another layer of the bouncy foam while reducing overall weight.
The exposed midsole design allows the foam to deform naturally with terrain — a stark contrast to the textile-wrapped approach of the original. Nike has restricted this wrap to just the forefoot section, maintaining structure where you need it while allowing heel flexibility for varied strike patterns.
Breathing Room Where It Counts
Trail runners know the frustration of shoes that fit perfectly in the store but become absolutely unbearable after mile 20. The ACG Ultrafly addresses this with a wider last throughout, but particularly in the toe box. Your feet will thank you during those inevitable river crossings too, as the new mesh upper prioritizes drainage over the ripstop material of its predecessor.
The internal fit system includes a gusseted tongue and internal fit band, which help with dealing with debris, water, and the general unpredictability of trail surfaces.
Vibram Partnership Continues
The Litebase outsole carries over largely unchanged from the original, which isn’t necessarily a bad thing. Vibram’s lightest rubber compound strikes the right balance between grip and durability for race-day applications. At 3mm lug depth, it’s aggressive enough for technical terrain without becoming a mud magnet.
The Numbers Game
At 10.1oz for a men’s 10, the ACG Ultrafly shaves half an ounce from its predecessor while adding features. The 37mm heel and 28.5mm forefoot stack heights maintain the substantial cushioning platform, but with an 8.5mm drop that’s fairly standard for trail runners.
Spec Sheet
Model: Nike ACG Ultrafly
Weight: 10.1oz (men’s 10)
Stack Height: 37mm heel, 28.5mm forefoot
Drop: 8.5mm
Midsole: Dual-density ZoomX with ZoomX sockliner
Plate: 7/8-length split carbon fiber FlyPlate
Outsole: Vibram Litebase
Lug Height: 3mm
Upper: Unspecified
Pricing & Availability
Nike hasn’t announced official pricing yet, but the ACG Ultrafly should land somewhere in the $270-290 range when it releases in Spring 2026.
Recap
Nike ACG Ultrafly
Nike refines the Ultrafly trail runner by putting it in its ACG collection and fixing the original’s overly rigid carbon plate and narrow fit issues through 30,000 miles of testing.
