Leadville Trail 100 MTB is the race that arguably invented American endurance mountain biking. It grew out of the Leadville Trail 100 footrace, itself created by Ken Chlouber in 1983 as an attempt to give the town of Leadville an economic lifeline after the Climax Mine closed and gutted local employment.
2008–2010 were arguably the most pivotal years for the race's popularity, as Tour de France stars like Floyd Landis and, eventually, Lance Armstrong showed up to give it a go. The film Race Across the Sky, released in 2009, put the event on the map — in the years before social media, it was a DVD riders of that era watched over and over, and it kicked off the race's hockey-stick growth. After Life Time bought the race from its original owners, it gained national attention and has since established itself as the most prolific endurance MTB race in North America.
For amateurs, Leadville's appeal is that just finishing is an accomplishment in itself. But with a largely unchanged course over the years, riders come back year after year chasing their own personal best — the coveted sub-9-hour and sub-12-hour belt buckles are as iconic a symbol in American mountain biking as any jersey.
Now part of the Life Time Grand Prix, Leadville has become the race where the series' overall standings frequently get decided, given its late-summer slot and its reputation as the hardest single day on the LTGP calendar. Keegan Swenson's run of consecutive men's titles and Kate Courtney's sub-7-hour women's course record are the current benchmarks the field is chasing.
There's a single distance — the 100 miles is the entire identity of the race, along with the altitude that makes it brutal (the town of Leadville itself sits above 10,000 ft). There's no shorter 'entry' option at the flagship event itself; that role is filled by the separate LT100 qualifier races held around the country.
For 2027, in the wake of the Willow Fire's impact on course access, race directors have significantly altered the route. It remains to be seen whether that's a one-year fix or a lasting change.
Entry is primarily by lottery, which opened December 1–15, 2025 for the 2026 race and is notoriously hard to get into. Life Time also offers Training Camp + Entry packages (sold out for 2026 by early December), qualifier-coin entries earned at LT100 MTB qualifier races, and charity entries that bypass the lottery. Roughly 1,800 athletes take the start line each year; Life Time does not publicly disclose how many enter the lottery itself.