Our reviews are 100% organic. We do not accept payment for reviews or bundle with advertising budgets. In most cases, the brand is providing the product to our reviewers free of charge. Nike generated a lot of buzz last fall with the relaunch of its ACG (All Conditions Gear) sub-brand, folding all of Nike’s existing trail running models into the new line. The ACG Ultrafly Trail is the successor to the original shoe with the same namesake and serves as the high-performance model in the ACG lineup. Nike claims this particular shoe is the most race-tested model among the ACG athlete team over the past three years and was clearly designed for podium potential.
Upper & Fit
The two-layer upper is composed of Nike’s Breathable VaporMesh which looks tough and holds up well to penetration, but we did experience slight ripping of the outer layer during some off-trail adventuring. Breathability was underwhelming on warm days, and the shoes soaked up water and drained slowly through creek crossings and puddles. The traditional tongue design is well-cushioned, however, we’d prefer a touch more length for lace coverage. Lacing hardware and setup felt conventional and uninspired for the price point; we would love to see something comparable to higher performance laces like Brooks uses on the Cascadia Elite or Norda 005 Dyneema laces.
Built on the new ACG last, which is wider than previous trail models, we found this shoe to have a comfortably wide toe box. Our primary tester has a standard width foot and experienced ample room upfront in the toe box with a narrowed and more secure midfoot and heel area; the fit of the foot feels comfortable while providing the toes with room to wiggle. Plush padding in the heel provides additional comfort but can make lockdown slightly insecure on climbs where our testers felt some shifting.
Midsole & Ride
As we have come to expect from Nike, midsole technology is where the ACG Ultrafly Trail shines. Our testers incurred a slight break-in period (roughly 10 miles) before the ZoomX Foam midsole and carbon flyplate settled in. The shoe eventually offered strong propulsion, stability and responsiveness, with a dual-density midsole that includes two different formulations of ZoomX. At its core is a softer compound, while the larger external layer is firm. After 80-plus miles of testing, the midsole foam remained remarkably unscathed despite the amount of rock and branch hits. Sandwiched between the foam is a full-length carbon fiber flyplate that is less rigid than those on previous Ultrafly models, and has a longitudinal flex groove for torsional support.
The combination of plate and midsole compounds provides some of the best trail protection we have experienced, allowing us to confidently traverse over sharp rocks and scree, even during high mileage. It cruises exceptionally well at steady paces and accelerates with minimal effort. We tested the ride quality at conservative paces during loaded run-commutes where the miles rolled by comfortably, as well as on milder trails, gravel, fire roads and pavement where the combination becomes fast and efficient. One noteworthy exception is on highly technical, rock or root-strewn single-track, where the plate makes the shoe feel a bit stiff and hard to manipulate, especially on steep or twisty sections.
Outsole & Traction
Nike uses Vibram Megagrip on this model, and the directional arrow-like lug pattern and 3mm depth deliver confident, predictable traction across wet roots, mud and sand. The modest lug height allows the shoes to roll smoothly on asphalt but still provides impressive confidence on looser and muddier sections of trail. It doesn’t have a typical trail shoe feel on pavement, which is a real advantage for mixed-surface runners, and is optimal for trail ultras with periodic sections of road mixed in.
Verdict
The ACG Ultrafly Trail is a compelling, fast and comfortable hybrid trail racer for runners who spend most miles on milder trails, gravel and fire roads and asphalt or concrete. Nike designed this shoe for athletes to wear from start line to podium at the biggest trail races in the world, and it has attributes that front-of-the-pack racers and competitive mid-pack runners will love.
The design favors courses that aren’t too steep or technical, so in terms of high profile ultramarathons, it’s better suited for Western States or Leadville 100.
Pros
- Lively, propulsive ride from ZoomX and carbon plate
- Excellent mixed-surface traction from Vibram Megagrip
- Durable-looking upper; outer layer resists full penetration from snags
- Comfortable tongue and overall cushioning for long miles
Cons
- Sub-par breathability and slow water drainage
- Heel lockdown can be inconsistent
- Too stiff on very technical, rooty and rocky trails
- Conventional lacing hardware feels minimal for the price
The Nike ACG Ultrafly Trail is available in unisex sizing version at www.nike.com.
Features and Specs:
- Weight: 10.12oz men’s / 7.93oz women’s
- Stack Height (heel/toe, in mm): 37mm / 28.5mm
- Heel-Toe Drop (mm): 8.5mm
- Upper: Nike VaporMesh
- Midsole: Nike ZoomX foam
- Full length carbon flyplate
- Outsole: Vibram Megagrip
- Four Color Options
- MSRP: $260