Ron Spargo, 67, was found by a passing motorist in the NSW Southern Tablelands just before 10pm on Sunday, hours after starting the long-distance race.

Police are still investigating the tragic incident, but say it's possible he may have been struck by a vehicle, collided with wildlife, or fallen from his bike.

Phillip Maas from the Peninsula Pedallers Cycling Club said Mr Spargo was a passionate cyclist who rode an average of 1000 kilometres each month.

"He wasn't one for taking risks," he said. "With the number of kilometres he rode, he was certainly very experienced."

A retired engineer, Mr Spargo lived in Berwick with his wife Brenda, who was also a member of the Peninsula Pedallers.

Mr Maas said club members were devastated at the news, "especially for his wife," who was a former club president.

Mr Spargo had completed a 600-kilometre race in northern Queensland a few months ago, but the Sydney Melbourne 1200 would have been his longest ride, Mr Maas said.

He also swam in the world's biggest open water race, the Lorne Pier to Pub, many times over the years.  

Mr and Mrs Spargo had two children and a number of grandchildren.

"It's very sad," Mr Maas said.

Club members will discuss a tribute to Mr Spargo when they meet on Monday night.

Race records show he had passed the Marulan checkpoint, 224 kilometres into the race, before the accident occurred.

Audax Australia Cycling Club confirmed the death near the small town of Bungonia, east of Goulburn, in a statement on its website.

"The ride organisers are helping police with their investigation," the statement said.

"The ride organisers and the wider Audax community extend their sympathies to his family and friends at this very sad time."

Police said the circumstances of the incident on Oallen Ford Road were unclear.

"It is possible the cyclist was struck by a vehicle which left the scene, collided with wildlife, or came off his bike for some other reason," police said.

Chief Inspector Brendan Bernie said the cyclist had sustained fatal head injuries.

"He was discovered at 10pm, but we do not know at this point what time the actual accident occurred," he said.

The man was one of more than 40 riders who set off from under the Sydney Harbour Bridge on Sunday morning.

The remaining riders made their way to Canberra and were heading over the Snowy Mountains before crossing the Murray River and travelling through Victorian farming country to Melbourne.

They're expected to arrive in Melbourne on Thursday.

A police spokesperson said the man's family had been notified and inquiries were continuing.

"In regards to his injuries, we will know more after the post mortem is conducted," the  spokespersonsaid.

"They will determine what injuries were sustained. I believe this post mortem will be held in the next couple of days.

"So at this stage, we are seeking assistance from the public to try and ascertain exactly what has occurred.

"We are appealing to anyone with information as we are still just exploring what has led to the death of this fellow."

Police, including officers from the crash investigation unit, remained at the scene overnight.

Anyone who saw the incident or with information is urged to contact Crime Stoppers on 1800 333 000.

The story Victorian cyclist, 67, found dead on road while riding from Sydney to Melbourne was originally published on The Age.