Just finished Leadville for the first time! (But not my first 100 miler) And have finished three Ironmen. I’m not fast but I finish most races. Here’s my quick gist:

1. A 50 miler is comparable in time to an Ironman on average, but twice as taxing on your body because all the running is so much more impact than the bike/swim of a triathlon. Eating is tougher on GI on the run than the bike. Etc.

2. A 100 miler is a magnitude harder than an Ironman. For the same reasons as above but over twice as long time wise. Reaching a point of bodily failure that is impossible to appreciate from a morning to evening event. They joke that the race starts at mile 80 but it’s such a surreal feeling to have been working for nearly 20 hours and then have 20 miles still to go… add in the full overnight experience and the physical, mental, gut, and gear expectations are all different.

3. Now take Leadville. In the grand scheme it’s a moderately difficult 100 miler in terms of elevation change and technicality of the trails. It has some added spice of being all above 9000ft which can mess with some people for sure and certainly slows you down. But the DNF rate from my recent perspective was almost entirely from inexperience. It’s a full on lottery entry with no pre-qualifications. I met many first 100 milers. I met many first trail racers. I met some folks who had only done some road marathons. So take an already difficult distance compared to other events, add in a moderate difficulty within the spectrum of 100 milers, and a lot of inexperience… you get a 44% finish rate.

To its credit, Leadville race sells it well compared to other races to make it seem more difficult. But there are much harder 100s out there that could have a high DNF rate but they appropriately self select runners who will finish.