Luke Plapp's disastrous Paris Olympics ended with abdominal surgery and left plenty of fire in his belly.

He turned that Games gloom into gold on Thursday, holding off fellow Australian cycling star Jay Vine for his third national time trial championship.

Plapp beat Vine by just 8.77 seconds on Thursday over the 38.4km course at Bold Park in Perth.

It is the third win for Plapp in the event, having also taken it out in 2021. He will also be the three-time defending champion on Sunday in the men's elite road race.

Earlier on Thursday, Brodie Chapman fulfilled her destiny, succeeding Grace Brown as the women's elite time trial champion.

Plapp was confident of a strong time trial result on day one of the Olympics, but he was among several riders to crash out in treacherous conditions.

He suffered a nasty abdominal wound that needed surgery, sidelining him for several months.

"I really thought I was going to light up the Games halfway through last year. I knew I was right up there with the world's best 'TTers'," he said.

"Unfortunately the results weren't there, but I knew the legs were capable of it, so it was a lot of fire in the belly to go out there and prove it again."

As defending champion, Plapp (Jayco AlUla) was the last rider to start in the elite men's event and he clocked 46 minutes 33 seconds.

Vine (UAE Team Emirates), the second-last starter and the 2023 winner, had a fast finish and posted 46:41.78.

Plapp's teammate Kelland O'Brien, a member of the team pursuit squad that won gold on the track at the Paris Games, was 54.94 seconds behind him for the bronze medal.

Chapman, 33, comfortably took out the elite women's time trial on day two of the nationals, after finishing third in 2023 and runner-up last year.

The 2023 Australian road race champion, Chapman was favourite to claim the championship, and duly delivered.

The new recruit for the UAE Team ADQ squad clocked 39 minutes 59.51 seconds over the women's 28.8km course.

She beat Liv AlUla Jayco rider Amber Pate by 32.7 seconds, with Anya Louw (AG Insurance Soudal) 1:00.99 further back in third.

Brown retired from cycling at the end of a stellar 2024 campaign, highlighted by the Olympic gold medal on the same day as Plapp's crash and then her first world title in the time trial.

She and Chapman were in the Australian team that won the mixed relay event last year at the worlds.

"When you want to improve and do see improvements, it definitely feels really good, but the sights are always set higher and higher," Chapman said after her win.

"Now I've got to go back to Europe and there's a whole new level of competition there. So that's the next goal, to see how I can stay consistent and also continually improve.''

Also on Thursday, Alii Anderson joined Zac Marriage as the national under-23 time trial champions. Anderson beat fellow rising star Felicity Wilson-Haffenden by just 1.82 seconds.

Meanwhile, Australian para cycling great Carol Cooke has competed in her last time trial at the nationals.

The 63-year-old, a three-time Paralympic gold medallist and nine-time world champion, will also compete on Saturday in the para cycling road races.

She was the only competitor on Thursday in the women's T2 category.

"I have no qualms about finishing up, it's time and I'm really happy that I get to be in beautiful Perth, somewhere different, to finish it off," Cooke said.

"I've seen para cycling change from 2011 until now and I'm very proud of how I've been able to help get it to where it is now.

"There's still a long way to go and I will probably still be around, bugging people until the day I die, most likely."

The road nationals have moved to Perth after more than a decade at Ballarat and nearby Buninyong.