In July, cross-country skiers are as rare as Christmas ornaments. Unless they’re on roller skis like Lars Floras and his friends. No snow is no problem for these elite cross-country skiers. They just pull into a sno park, snap their boots into the bindings on a pair of roller skis and head off toward Mount Bachelor-on paved shoulders of roads. “This is the most specific training we can get for cross-country skiing without being on snow,” said Flora, 31, a Portland native who represented the United States in the 2002 and 2006 Winter Olympics.