Fresh off his stunning victory at the Western States 100, where he clocked one of the fastest times in the event’s history, American ultrarunner Caleb Olsen has become a central figure in the trail running world. We met with him in Chamonix to discuss his record-breaking run and future ambitions. While we had his ear, we discussed the groundbreaking new gear from Nike and their ACG brand.
Interview by Alex Filiti
A New Approach To Western States for Caleb Olsen
Caleb, thank you so much for being here with us today in Chamonix. You’re the very recent winner of Western States 100 in a fantastic time of 14 hours and 11 minutes. Can you talk us through that day? What did you go through to achieve one of the greatest runs ever on that course?
Caleb Olsen: Yeah, thanks for having me. That was an amazing day. I had done Western States the previous year and got fifth. It was a great debut but felt like I’d still left a lot of room for improvement. This time, I wanted to go back, try again and see how much time I could knock off. I went into it with this mindset of wanting to break through a barrier, mentally and physically.
On this run, I wanted to get myself to a point earlier in the race where I felt like I was really pushing through a challenge. So I went out harder than I had the previous year, went out fast, and decided to just go for it. At this race, I wanted to see what it felt like to get into that tough spot earlier in the day. It worked out really well. I had a day that I’m super proud of. It seems like going out faster and harder is what made the difference.
Was that a deliberate strategy or something you decided on the day?
Caleb Olsen: No, going into it, my strategy was to go out harder. There were a lot of factors that were different. I showed up fitter and with a bit more confidence. Earlier in the year at Trans Grand Canaria, I had a good race and proved to myself that I belonged more up at the front of these big races. I took that confidence, the better fitness, the experience on the course, and the fact that it wasn’t my first 100-miler this year. All of that together let me feel more comfortable pushing the pace hard, feeling like it was something I could sustain the whole day. I just raced a lot harder.
Caleb Olsen’s Preparation and Planning for Western States and Future Aspirations
Western States is one of the fastest 100-mile races on the planet. How do you get fit for it specifically? What’s the key advice you’d give?
Caleb Olsen: It’s funny because Western States is one of the faster 100-mile races, but it still isn’t that fast really. I averaged around 8:30 pace. So while it’s fast compared to a race like UTMB, you can still get away with training that focuses more on all-day endurance than top-end speed. A lot of my key sessions were focused on uphill, trying to get the legs strong, beating up the quads on downhills. A little bit of speed work, but that was definitely not the key focus. It was more about being able to maintain a good effort on back-to-back long runs and keep up that muscular endurance.
Now that you’ve achieved a race like this, what can you dream of? Are you tempted to try again next year and improve, or are there other challenges?
Caleb Olsen: I’m a little tempted to try again next year because it’s a race I feel I can do well at. It’s appealing to go back multiple times and see what your limit is. But I also feel like I’ve gotten what I wanted out of that race. Maybe I could shave some more minutes off, but I want to keep my schedule fresh and exciting. I’m surrounded by the Mont-Blanc energy here in Chamonix, and it’s pretty appealing to maybe focus all my effort on coming back and doing UTMB next year.
Nike’s New Trail Tech and Merger With ACG
That’s very interesting news. In between this year’s UTMB and next year’s, there’s a big change happening for your main sponsor, Nike. Nike Trail is transitioning to ACG. Can you explain what ACG stands for and what it means to you?
Caleb Olsen: Sure. ACG stands for All Conditions Gear. The main difference is I feel like I’m getting a higher level of support. ACG seems like the team is united around making gear that can handle all kinds of different conditions. Nike Trail was focused on high-quality, fast shoes for races like Western States.
As I get more excited about races like UTMB and off-trail adventures, ACG brings more of a wild spirit to it. The team is bigger, there are greater resources, more innovation and customization. We can design gear specifically meant for objectives that excite me, like playing in the mountains, doing Mont-Blanc, or scrambling.
That’s a perfect segue. You just teased the new gear. Can you talk about the shoe right behind you?
Caleb Olsen: This is the Nike ACG Ultra Fly. I love it because I’ve had a real influence in helping design it. Since early on, I’ve been involved wear-testing and giving feedback. I wore a version of this shoe at Western States in 2024 and ended up changing shoes twice because the foam felt packed down after 40 miles. When I gave that feedback, they sent me updated foams, and we went in a new direction. This year, I wore the same shoe the whole 100 miles and it felt great, responsive, and bouncy. To see that huge improvement in one year was really cool.
Can you show us a detail that came directly from your feedback?
Caleb Olsen: One thing that’s important to me is being able to use these shoes on more than just fast courses; I want to use them on technical, mountainous races. So they needed a grip I could trust. I like the Vibram outsole and the lug pattern.
My main feedback on the previous version was that I didn’t feel stable on technical terrain. A priority for this ACG iteration was trust and stability. The upper holds your forefoot securely, there’s a beefy heel cup that locks you in. It’s a super shoe on a big, bouncy foam, but it also feels stable and secure.
Caleb Olsen’s Secret Weapon: ACG Radical Airflow
What blew up the internet wasn’t necessarily the shoe, it was your top. Can you explain what it is and what it did for you?
Caleb Olsen: This is the ACG Radical Airflow Top. I wore a prototype for the first time in 2024 and remember just walking around and feeling the air going through all the holes. It felt colder than not wearing a shirt. I tested it in an 80-degree heat chamber on the Nike campus and gave feedback on things like extra fabric in the armpit that was blocking airflow. We fine-tuned it for Western States. It’s rare to see breakthrough innovation in apparel. This felt like it gave me an edge. When this fabric is wet, it stays wet for a long time and accelerates evaporation, maximizing your cooling.
How did it feel against your skin?
Caleb Olsen: I’m not a scientist, but I know the feeling. At mile 80, over 100 degrees in the canyons, my crew would dump water on me. The initial ice bath sensation was perpetuated by the shirt; it extended that cooling feeling. It felt like remaining in a fridge after being covered in water. Between the sun protection and what felt like a constant cooling effect, I think it took time off my day.
If you could keep only one piece of equipment, the Ultra Fly or the shirt, which one would it be?
Caleb Olsen: That’s a tough question. I think I would maybe go for the shirt, but not just for the performance benefits. It stood out enough that it helped me feel like I had a secret weapon. Everybody has good running shoes. I probably could have run close to as fast in another top shoe. But this made me feel like I had something no one else did. It was a fun, crazy thing that let me stand out. Even during the race, other racers would come up and say, ‘Dude, can I feel your arm? What are you wearing?’ I’d get my arm petted. I’d go with the top because it’s so different from anything we’d seen before.
Did you hear or read any funny comments about the shirt?
Caleb Olsen: I don’t think I’ve ever gotten so many comments. Some of my favorites were people finding the little wrappers for the Asian pears at the grocery store—the plastic mesh that looks like this fabric. People would put those on their arms saying, ‘Just a few more and we’ll have built out the full shirt.’ There were a lot of them that made me laugh.
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