Catch a candid conversation with 4-time X Games gold medalist Ryan Nyquist. The 38-year-old has been riding BMX professionally since 1995, but a chance encounter in Puerto Rico got him on a mountain bike for the first time. After flying over the handlebars, Nyquist told himself, “Never am I ever going to do this again.”

But more than a decade later, he found himself competing in one of the most prestigious mountain bike competitions in...