Update Friday 2.15pm:
NSW Ambulance now believe the man was riding a motorbike when he struck an object and fell heavily.
He was riding on the Belanglo Plateau Fire Trail at the time.
Three ambulance crews, a Toll helicopter, police and SES remain at the scene.
A spokesperson said a decision would be made whether to transport the man by road or air. He confirmed the man had a head injury, which was of concern.
A male mountain bike rider has suspected head and hip injuries after falling off his bike in Belanglo State Forest.
A NSW Ambulance spokesperson said crews received the call just after midday, Friday December 8.
“A number of units responded and are currently on scene,” the spokesperson said.
SES crews have also been activated.
The spokesperson said a helicopter had been tasked to assist the man, believed to be between 35 and 40-years-old.
“The helicopter is currently responding, but the man does look to be stable at the moment” the spokesperson said.
More to come.