Nike ACG Ultrafly Trail Review

The Nike ACG Ultrafly Trail is for you if...

You want a surprisingly restrained, easy-to-trust trail race day option

You want the best grip for wet rock surfaces

You want a combination of an accommodating fit and a great lockdown 

What is the Nike ACG Ultrafly Trail made for?

The Nike ACG brand is having its moment right now. Obviously Nike isn't new to the game, but the ACG (All Conditions Gear) rebrand is giving Nike a chance to reestablish itself as the elite, all-weather outdoors brand to beat. After seeing their bright, unmissable orange colorway all over the Italian slopes this winter, across the floor at TRE, and everywhere else we've looked, the rebranding has been apparent and LOUD and exciting. But for us, Nike's latest trail super shoe, the ACG Ultrafly Trail, feels especially hit-or-miss for whether it justifies its place among that hype.

For this shoe, our word of the day is going to be "divisive."

The ACG Ultrafly Trail is meant to be a wildly fast trail racing shoe, with the cushioning needed to tackle long-distance events. With an exceptionally propulsive and energetic Zoom-X foam, a carbon fiber FlyPlate, and a Vibram outsole, there's no denying that the ACG Ultrafly Trail feels light and quick underfoot. But we had some questions over how far its performance can be stretched. The shoe seemed universally at home on easy-to-moderate trails where we could open up our strides and pick up our pace, but as trails got more technical and strides got choppier, our experiences started to polarize. The shoe's fit seems tailored for narrow, compact feet, and we think that runners who want a little more room in their toe boxes will want to look elsewhere.

Comfort

Across the board, we found the Nike ACG Ultrafly Trail to feel firmer underfoot, narrower in width, and surprisingly padded for a minimalistic upper. The heel collar seemed high on initial step-in, but created no Achilles issues or abrasion as we ran, with just enough padding provided in the shoe's tongue and around our ankles.

There was a sharp divide in our experience with this shoe. For most of us, this shoe hit the mark on comfort. A minimalist approach to an upper, paired with a firm, snappy feel, aligned with what we were expecting, comfort-wise, from an apex trail-racing super shoe.

But then there's the other side of the coin. One tester experienced a long break-in period before reaching a tolerable comfort level, even cutting their first run a few miles short, and still found the shoe to be too narrow and too firm for their liking. If the initially firm underfoot feel doesn't work for you, then its muscle-like density can undercut your comfort and enjoyment of the shoes throughout your introductory miles.

Performance

The shoe's performance provided a nice reconciliation point for our team. We collectively agreed that the shoe was fast, but best suited to well-groomed trails. We pushed the pace easily along fire roads, through fast hill repeats, and through other workouts and courses where traction wasn't a concern and speed was key.

It's light and responsive, facilitating quick toe-offs through its well-designed carbon plating. The decision to split the carbon plate into two separate halves (medial and lateral) allowed the shoe to adapt and flex as needed across uneven terrain. The plate is still fairly rigid overall, but it's more flexible than before.

As far as traction and footing, the ACG Ultrafly Trail felt immediately familiar and trustworthy on the well-manicured, moderately technical trails that it was designed for. Even when we challenged the shoes with more extreme terrain, our footing stayed confident, and the Vibram outsole handled wet and alternative terrain with ease, as always. We could have done with slightly deeper lugs, but the shoe meets its intended use case well as-is.

Fit

As it did in the Comfort section, the ACG Ultrafly Trail had us divided again when it came to fit.

For those of us with narrow feet, we had our Cinderella experience. We found that narrow-footed runners might want a touch more security around their metatarsal heads, but the tapered toe box was a non-issue, and we achieved a good, reliable lockdown easily.

For others, fit issues abounded and contributed to our overall discomfort in the shoe. For a unisex shoe, we expected a little more wiggle room in width and volume.

One tester with a wider forefoot and narrower heel found the shoe's dimensions to run completely counter to their own, which made getting a secure lockdown a challenge. The toebox and midfoot both felt "binding." Although things got better as the shoe broke in a bit, it never got "good," and the thinness of the tongue made it difficult to cinch things down or make adjustments.