Article by Sam Winebaum
We all saw Caleb Olson’wild Western States running shirt and something new on his feet as he flew to victory at the 2025 Western States 100 in the 2nd fastest time in history (14:11:25) and only 2 minutes off the record.
Now we know more as Nike announces the ACG Ultrafly and Radical AirFlow kit coming Spring 2026.
In a related development Nike also rebranded its elite trail running gear to ACG and brought its elite trail athletes under a new team umbrella “The All Conditions Racing Department” with 22 athletes representing 22 countries and 5 US states.
ACG Ultrafly (pricing TBD)
The ACG Ultrafly is an evolution of the original Ultrafly Trail (RTR Review). The original Ultrafly was basically a road super shoe with a Zoom X midsole, a very stiff full length carbon plate and in a very welcome first for Nike, a Vibram Megagrip outsole.
The new ACG Ultrafly went through 13 rounds of testing and trdy 30,000 miles, the most ever for a Nike shoe with Racing Department athletes (of course) and other athletes participating.
The result is a 37mm heel / 28.5mm forefoot (slightly less the UF 1’s 38.5 mm / 30 mm) trail supershoe with:
a dual density ZoomX newly tuned midsole foam with top trail (or likely for any road shoe as well) energy return of 85%,
a ⅞ length carbon plate split down the middle to better conform to terrain and with some flexibility (we asked to Nike to show us the flex during the media call).
The Vibram MegaGrip Litebase with 3mm lugs outsole continues.
The outsole pattern shows broader longer contact surface lugs in a simpler layout with less multi angular lug shaping (see UF1 pic below).
ACG Ultrafly
Ultrafly Trail 1
We expect the new design, along with many small holes through to the midsole, will show improved smooth terrain feel and assist with more technical terrain feel and overall flexibility if maybe with a bit less loose terrain grip.
In Nike spec US M 10 the weight is 10.12 oz / 287g with the women’s 228g US8. Our US men’s 10 test samples of the Ultrafly 1 were 10.6 oz/ 304g so we see a welcome weight drop to a competitive weight for a shoe in its class.
We have fewer details on the upper (although the muddy pairs in the PR pictures look quite a bit like Matryx but with thin overlays and not woven in support) but Nike tells us the UF 2 is on a wider yet last than v1 (and v1 was very broad and not exactly secure) especially at the toe box so we hope hold is not impacted.
The upper is said to be faster-draining and more breathable. A good thing as V1’s ripstop-like material wasn’t that good in that department Everything points to a state of the art trail racing shoe for elites with a more accessible design for the rest of us and great versatility. In fact Nike tells us Eliud Kipchoge is also a big fan (and tested)for his runs in Kenya, mostly on dirt roads.
Radical AirFlow
While Caleb’s shoes were a bit hard to see his top was not. Holy Holes!
Nike and its labs, again joined by much testing by athletes set out to create a top that effectively cooled athletes with a focus initially on the always super hot Western States conditions.
The 100% recycled knit is built into a system of essentially air ducts to direct the flow of air to the body and accelerate evaporative cooling. Athletes report a “breezy sensation” and that it is like “stepping into a fridge”. I imagine especially if dosed with some ice water along the way!
The arm openings are of course designed for motion but also assist in increasing air flow.
I tend to run hot and don’t care about looks and think the combination of a loose fit and all the air moving holes can really assist in cooling on the go. I also think when worn under a shell in wet or cooler conditions the evaporation may make those runs yet more comfortable. Nike is also working on how the technology might be applied to other sports.
These innovative new products, their recent success at Western States, and the formation of the All Conditions Department for sure point to Nike’s now far better defined and we hope executed commitment to off road running.
RoadTrailRun will be updating this article and will have a video after we see both in person and do a demo run in the ACG Ultrafly Sept. 28 at UTMB
Sam is the Editor and Founder of Road Trail Run. He is in his 60’s with 2025 Sam’s 54th year of running roads and trails. He has a decades old 2:28 marathon PR. These days he runs halves in the just sub 1:43 range if he gets very, very lucky. Sam trains 30-40 miles per week mostly at moderate paces on the roads and trails of New Hampshire and Utah be it on the run, hiking or on nordic skis. He is 5’9” tall and weighs about 160 lbs, if he is not enjoying too many fine New England IPA’s.
1 comment:
Amazing..."a breezy sensation"...that's some in depth testing to figure that out from that shirt.;)
Post a Comment