It can have some extreme aspects. The trail goes over two passes that are above 12,000 ft. It is also 40 mi long . The final bit of the race is a descent on narrow Nordic skis straight down Aspen ski area. Weather is iffy. I did it once in 2003 and the temperature dropped to -15F and many teams had to drop due to frostbite. In 2007 there was strong winds and white out conditions on Taylor pass causing difficult navigation.
What times are expected. The fastest racers may do the 40 mi in 7.5 to 8 hrs. My first year we finished in 15 hrs. Part of this was due to the cold weather. Our goal this year is to finish in under 11 hrs.