An Ambulance Victoria spokesperson said the man sustained head and chest injuries during a practice ride on Sunday and was first taken by ambulance to Bendigo Health in a serious condition just after 11am.

An an air ambulance also arrived at the scene but the patient was deemed unsuitable for flying at the time, the spokesperson said.

A Bendigo Health spokesperson said the patient was transported to the The Alfred hospital in a serious condition a short while after arriving for treatment.

Yesterday a spokesperson from The Alfred said the man remained in a critical but stable condition.

Bendigo Motorcycle Club's vice president Peter Clarke said the incident happened when the rider, an 18-year-old, was taking part in a seniors' ride with about 26 others. 

"He crashed, we think the bike landed on him," he said.

He said the club's thoughts were with the teen's family and he hoped there would be a fast recovery for the young rider, who was also new to the sport.

"It was his first time round the track," he said.

"It was unlucky, he could have had that crash 10 times over and got back up."

He said such incidents were rare at the Ravenswood track where the Bendigo Motorcycle Club hold their regular meets, and the site of the coming Australian Post Classic Motocross Championships later this month.

"It's the first helicopter I've seen at the track since I started at the club in 1968," he said.

"Touch wood, we've also been lucky not to have many serious incidents in the past 20 years or so.

"Our track is one of the safer tracks around the state."

He said one of the problems for inexperienced motocross drivers was a lack of ride parks in central Victoria to learn how to ride dirt bikes.