After a three week sabbatical at home in Tasmania, the 21-year-old returned to Sydney on Sunday and blitzed a strong field to claim the Nepean Triathlon.

Birtwhistle finished the one kilometre swim, flat 30km ride and 10km run in one hour, 30 minutes and three seconds – 46 seconds faster than Rio Olympian Ryan Bailie in second.

The former Riverside High student, who missed out on joining Bailie, Ryan Fisher and Aaron Royle on a plane to South America in August, set up the victory with a powerful bike ride.

Birtwhistle was close up on the swim and he and Bailie dominated the ride before the Tasmanian broke away on foot – running home in 32.31. Ironman distance triathlete David Mainwaring (1:31:13) crossed the line in third place, while the women’s race was taken out by 2014 winner and Rio representative Ashleigh Gentle.

“I’ve been second (to Aaron Royle – ninth in Rio) for the past two years so it’s nice to break through for a victory,” said Birtwhistle.

“It’s a straight forward course but one that I really enjoy, given my previous results here, particularly winning the Youth Olympics.

“And I put it down to the work I have done back home in Launceston on the time trial bike.

“In the past I have just maintained my fitness for this time of the year but this year I have taken it up a notch and it has certainly paid off. The bike is at the moment my strongest leg.”

That’s a big statement given the fact that Birtwhistle came from a solid athletics background that saw him represent Australia in IAAF World Cross Country and with outstanding results over 3000, 5000 and 10,000 metres on the track and road as he transitioned out of athletics to chase his Olympic dream in triathlon.

Birtwhistle is trained by Jamie Turner and is primarily based in Wollongong and Vitoria, Spain, and achieved his best World Series Triathlon race result in July – claiming silver in Hamburg, Germany.

Birtwhistle told Fairfax Media last week that Commonwealth Games qualification was his next big task with the 2020 Tokyo Olympics not too far off his mind either.

But for now, last year’s under-23 world champion is focused on this weekend’s Noosa Triathlon.