The Iditarod Trail Invitational (ITI) is the world’s longest winter ultramarathon by mountain bike, foot and ski. It follows the historic Iditarod Trail from Knik, Alaska, over the Alaska Range to McGrath and on to Nome. If you like to run and ride in severe winter conditions and sleep outside in the frozen tundra, this is the race for you. The question then becomes how much you can endure. The ITI offers two options: (1) a leisurely 350-mile journey, in which the middle of the pack finishes in five days; or (2) if you’ve managed to survive the 350-mile race in previous years, you’re eligible for an extended trip of 1,000 miles — in which case, good luck. Since the inaugural race in 2000, only 42 people have finished the 1,000-mile race to Nome. There’s one final catch. The ITI is completely unsupported, so all racers need to ship their food to designated post offices and make sure their bike is in top-notch shape (not to mention be one hell of a mechanic) because a technical on this route could add days to your trip. These photos, by endurance mountain biking legend and former ITI winner Mike Curiak, tell the story.