Usually when athletes go for a rollerski, they deal with a variety of challenges. Crappy pavement, angry drivers, and constant “where’s the snow” heckling is pretty standard no matter where you pick for a ski. But this past Saturday in Gatineau, Quebec, the greatest hazard was a rare one: other rollerskiers. The 257 rollerskiers who gathered together in the Gatineau Park signed in, posed for a picture, and then skied en masse for about 2...