The Leadville 100 Bike Race began after the Trail Run cemented itself as a world class ultra marathon worthy to be included in a serious runner’s “tick list.” Ken Clouber started the run after mining went bust in the 80s and the town needed a boost. Both events cover similar territory but vary slightly due terrain and permitting.
For more details check out the Leadville 100 Website and for a cool movie, see Race Across the Sky
Here is the Flyover:


You mention that running would be easier on the body…how is that possible? Running is far more abusive to the body then cycling is.
Well, at least when you’re running an ultra marathon your top speed maybe 8 mph, so barring crashes and sore backs, you’re may be right. I should have stated that TRAIL running is easier on the body than ROAD running. I recall a statement LA mentioned after running the NYC Marathon about it hurting. However, with good training, the myth about running being bad for you is ….well…a myth. See: http://health.usnews.com/blogs/on-fitness/2009/04/28/born-to-run-christopher-mcdougall-says-humans-evolved-to-run-like-the-tarahumara.html
Thank you for the great information. Loved the flyover and the vertical map!