Tom Pidcock underlined his status as the most exciting young cyclist in Britain as he stormed to victory in the men's Olympic mountain bike race in Izu.

Having already collected junior or under-23 world titles in cyclo-cross, mountain biking and on the road, the 21-year-old Yorkshireman took things to another level with an Olympic crown on Monday as he rode clear of the field, having time to grab a Union flag and hold it aloft as he crossed the line.

Even with the celebrations, his margin of victory was 20 seconds over world number one Mathias Flueckiger – the only man who had looked capable of staying in touching distance once Pidcock had made his move midway through the 28.25km race.

The watching crowd – not subject to the same restrictions as those in Tokyo – were denied the hotly anticipated battle with Mathieu van der Poel, who crashed heavily in front of Pidcock early in the race before withdrawing on the fifth lap, but they were still treated to a phenomenal performance.

"It's pretty surreal," Pidcock said. "Really I was trying to tell myself this week I would become an Olympian and that in itself is a pretty great achievement. But really my goal was to win. I was just telling myself that to keep myself calm. It's kind of incredible really."

Pidcock, whose qualification for the event was only confirmed in May, started on the fourth row on the grid but wasted no time in getting himself into a leading group, gaining 26 places by the end of the first full lap.

Tucked in behind Flueckiger and the other Swiss rider Nino Schurter, Pidcock made his move with 17km to go as he charged to the front, then kept the power down as his rivals one-by-one slipped back.

"I'm always better when I take control myself," he said of his tactics. "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. I'm happy this s**t's (the Olympic Games) only every four years because it's f***ing stressful."

As Pidcock rounded the bend on to the finishing line he grabbed a Union flag from a spectator to begin his celebrations, then after crossing the line he embraced coach Kurt Bogaerts, who has nursed him back to form after he broke a collarbone less than two months ago.

Van der Poel, among the pre-race favourites prior to the Games after spending six days in yellow at the Tour de France, was left to complain that a ramp that had been in place at the point where he crashed – tumbling off a high rock – had been removed for the race without his knowledge.

The Dutchman, who was sent for x-rays after the race, had been right in front of Pidcock at the moment he fell.

"I was behind him," Pidcock said. "He went very slow to the drop and I thought, 'I'm just going to back off, this might not end very well,' and when I came over the top he was tumbling down on the floor.

"It's not nice to see and I hope he's alright. We were training with the boardwalk there and then the boardwalk was not in the race.

"It looks like he thought it was still there but I don't know what he was thinking, you would have to ask him. But it's not nice to see on the first lap in the Olympics."