IZU, Japan—Britain’s Tom Pidcock became the youngest ever Olympic mountain bike champion as he left his rivals in a cloud of dust as he stormed to the gold medal on the Izu course on Monday. The relentless 21-year-old seized control after four laps of the 4.1km Izu circuit and he was never challenged, riding away to victory by 20 seconds ahead of Swiss Mathias Flueckiger. So far ahead was the Yorkshireman that he even had time to grab a British union flag as he crossed the finish line in front of an enthusiastic crowd who were permitted in. “I’m always better when I take control myself. I take my own lines, my own speed. Once we started I was fine, all the nerves kind of went and I concentrated on the race,” he said. “It’s nothing like any other race. The Olympics just transcends any sport. You compete and represent …