Australian professional rider Jason Lowndes is dead after he was struck from behind by a motorist at Mandurang, Victoria while training for the 2018 season.

The 23-year-old, who was set to ride with UK outfit JLT Condor in 2018 after spending the 2017 season with the Israel Cycling Academy, was airlifted to a Melbourne hospital on Friday but later died.

Police say he was hit at 10:15am by a Mazda sedan being driven by a 20-year-old Kangaroo Flat woman, who stopped at the scene and was later taken to a local hospital. She is assisting with inquiries.

Lowndes also rode for Australian pro continental team Drapac in 2016 and the Canadian Garneau-Québecor squad in 2015.

He was set to race the 3-7 January Cycling Australia FedUni Road National Championships, after finishing 10th in the under-23 road race this year.

SBS Cycling offers heartfelt condolences to the family and friends of Jason.