13.1 generally refers to the Half Marathon distance in running, exactly 13.1 miles, half of the full 26.2 mile marathon distance. 13.1 miles is also the standard running distance in a Half Ironman, also known as 70.3. Triathletes complete the 13.1 run at the end of the race after having first swam 1.2 miles and cycled 56 miles.
Take on one of the toughest cycling challenges in the world! Can you get to Vegas in 24 hours?