UPDATED 9.45AM: A cyclist was struck by a vehicle and flung from his bike in a hit-and-run crash that left him lying by the side of the road south of Sydney with a broken back.
Brendan Braid, 58, was found by a number of cyclists several minutes after the crash on the Old Princes Highway at Helensburgh early on Sunday.
He was curled up beside his mangled bike with fragments of a car mirror scattered around him, and is believed to have been knocked unconscious.
Mr Braid, a member of the Southern Cross Cycle Club, was taken to St George Hospital.
Police said he remained in a stable condition in the hospital's intensive care unit on Monday.
The cycling club said he had cracked lower vertebrae, internal bleeding, a broken ankle, broken leg, and extensive grazing and bruising.
Two cyclists found Mr Braid. They reported that the last car that passed them going up the hill was an older model white Ford Laser.
Police are now looking for the car, which had green P-plates and Victorian registration plates.
Acting Inspector Dan Richardson, from Wollongong police, said the cyclist was believed to have been riding alone and heading south on the Old Princes Highway about 6.15am on Sunday when the crash occurred.
The old highway was bypassed by the present Princes Motorway, and is usually quiet and popular with cyclists on weekends.
''We think the vehicle was travelling in the same direction as the cyclist when he was hit. We haven't been able to get any information from the cyclist because he can't remember the incident at all,'' acting Inspector Richardson said.
''He was located by other cyclists that had come up behind him shortly after it happened, and they immediately called the ambulance service.''
One person wrote on social media that the crash occurred at the top of Garrawarra Hill.
Another cyclist wrote on Facebook: "I got there at the same time as the ambulance and cannot believe that someone could drive off and leave someone in that condition."
Initial reports suggested Mr Braid's injuries were not too serious, but his injuries were found to be worse than first thought, acting Inspector Richardson said.
The cyclist had hit his head, and could not remember the incident.
Acting Inspector Richardson said police would like to speak to the driver of the white Ford Laser.
''At that time, there's not that many vehicles around. Speaking to the other cyclists, that vehicle was reported to us as being on the road at the same time,'' acting Inspector Richardson said.
Anyone who knows the identity of the driver or has information about the crash is urged to phone Crime Stoppers on 1800 333 000 or visit the Crime Stoppers online reporting page.