Who or what are the competitors in the main race run every May between Durango and Silverton in southwest Colorado, USA?

Question

A relay race is a track and field event in which athletes run a pre-set distance carrying a baton before passing it onto the next runner.

Answer 1

Cyclists racing a train
The Iron Horse Bicycle Classic was first run in the late 19th century when the train was under steam, and has been run regularly since 1971. The race is run on Memorial Day weekend and marks the first spring run of the train.