A male cyclist was taken to hospital in a critical condition after crashing during a road race north of Sydney this morning.

The CareFlight rapid response rescue helicopter was called to West Head Road in Ku-ring-Gai Chase National Park about 9am.

It landed on a rock ledge about 2 km north of the Liberator General San Martin Drive intersection.

The medical team joined NSW Ambulance paramedics in treating the injured cyclist, aged about 60, for a serious head injury.

He was intubated and sedated before being placed in a road ambulance where the medical team continued treatment on the way to Royal North Shore Hospital.