Adelaide son's plea after his father was hit by a car while cycling

An Adelaide father is fighting for life after he was struck by a car on a busy road.

Jason Carmichael, 55, was hit by a blue Honda along Chandlers Hill Road, Happy Valley just after 5pm.

Carmichael was rushed to hospital, along with the 66-year-old driver, who underwent a blood test.

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The cyclist's son Simon was contacted after his dad was taken to hospital.

"I got a call from the hospital about 20 minutes after it happened that he had been hit by a car," he said.

"He will recover."

Major crash investigators spent hours scouring the scene to try to piece together how the accident occurred.

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Locals said cyclists frequent the area at all times of day.

Some believe improved safety measures are urgently needed along the busy stretch of road to prevent similar incidents.

'I wish there was a pathway there so then it was just a better place for cyclists to be," resident Teagan Engledow said.

Jason remains in an induced coma at the Flinders Medical Centre, as doctors try to determine the extent of his injuries.