Several Minnesota men just finished biking their way across 350 miles of rugged Alaskan wilderness on wide, knobby tires, having taken part in the frigid, grueling Iditarod Trail Invitational.
It's a route better known for sled dog racing — but the trail is a good test for fat bikes. They're basically modified mountain bikes with very low air pressure tires, making it easier to ride in difficult conditions like heavy snow.
"It's an incredibly hard, incredibly difficult, potentially very, very dangerous race with extreme weather and extreme temperatures," said Charly Tri of Rochester, Minn., who was one of about 40 racers.
Tri, 37, finished seventh. It was his second fat bike Iditarod, which has checkpoints about every 40 miles. But for the most part, riders are surrounded by snow, trees, mountains and the occasional moose or wolf.
"It's not like someone can drive out and pick you up," Tri said. "The Alaskan Air Force has to come out in helicopters to come get you, it's so extremely remote."
Iditarod racers get little to no sleep over the course of several days. 39-year-old Ben Doom of St. Cloud, Minn., who finished just ahead of Tri, took a brief respite after he found himself running into rocks and stumps.
"So I just went 20 feet off trail, threw down my sleeping pad and sleeping bag, and slept a solid two and a half hours," he said. "It (the race) took me two days and eight hours or so, and I slept probably about five hours."
This year was the fastest fat bike Iditarod in the race's 13-year history. Much of the race was done with temperatures above zero. Jayme Zylstra, who tracked her husband Ken's progress online this year, says in Ken's first race in 2013, temperatures dipped in the negative 30s.
"I'm worried every single day that he's out there, because I would say my nightmare would be to get that phone call that he's frozen somewhere," she said.
Ken Zylstra finished the race Wednesday. At the end of the 350-mile trail, racers gather at a lodge where they finally eat a real meal and exchange stories.
Why do the bikers do it? "I'm sure it's different for everyone, but the common denominator really is just pushing yourself to the limit and seeing what you're capable of," said Tri.