LAHTI, Finland — Here’s the basics: fast and firm tracks, cloudless skies, and once again a stacked field for the final event of the 2017 Nordic World Championships: the men’s 50-kilometer freestyle mass start. Over the course of the 50 k, Canada’s Harvey had to think about one thing: be up front near the top three in order to shadow Norway’s Martin Johnsrud Sundby’s inevitable gut punch in the last kilometer. What he didn’t have...