Reid, who lists Cathy Freeman as one of her heroes, "zig-zagged" her way to the C1-3 500m time trial gold and broke her own world record .

She is the rarest of athletes in Australian sport - an elite Indigenous cyclist.

"Being a proud Aboriginal woman from Guringai and Wemba-Wemba, I hope to inspire more indigenous kids with disabilities back in Australia to start with sports and achieve their dreams like I have," Reid said.

Reid went one better than her 500m time trial silver medal at the 2016 Rio Games, dominating the event on Friday at Tokyo's Izu Velodrome.

The three-time Paralympian - she swam in London 2012 and then switched to cycling - clocked 38.487 seconds and was the only rider to go sub-39.

Also on Friday, Alistair Donohoe repeated his result from Rio when he won silver in the C5 4000m individual pursuit while Gordon Allan finished fifth in the C1-3 1000m time trial.

Reid, 25, broke the 38.918 world record for the C2 class she set last November at Brisbane's Anna Meares Velodrome.

She won from Dutch rider Alyda Norbruis (39.002) and China's Qian Wangwei (41.403), who broke the world record for the C1 class.

It was Australia's third cycling gold medal at the Tokyo Games.

Reid, who has cerebral palsy, overcame a shaky start to snare the gold medal.

"It just means everything ... I was hoping for the world record, but I was bit everywhere on the track, a bit like a zig-zag," she told Channel Seven.

"That's because of my cerebral palsy, so it can be very interesting when I ride."

Reid's switch from cycling to swimming hasn't all been success and speed.

Three years ago, she was accused in the media of exaggerating her symptoms.

The Australian Paralympic Committee, now Paralympics Australia, strongly backed Reid at the time, saying she has "multiple impairments".

"The last five years have been up and down, so to get gold is just amazing," she said.

"It feels so great."

Donohoe's late surge in his qualifying ride earlier on Friday put him into the gold medal ride-off against Frenchman Dorian Foulon, who broke the world record with his fastest time of 4:18.274.

Foulon led from the start in the final and the Australian could not bridge the gap.

The French star clocked 4:20.757 and Donohoe posted 4:24.095.

Donohoe wants Games redemption in next week's road racing.

He was sprinting for a road race gold medal in Rio when a collision took him out and he was relegated to fifth after he ran across the line without his bike.

Australia is second on the cycling medal tally behind Great Britain with three gold, two silver and a bronze.

Australian Associated Press