Louis Phillips, a Canton resident, collided with a westbound Chevrolet pickup truck on Cumming Highway shortly before 5 p.m. Saturday, according to police reports.
Phillips was also traveling westbound, said Lt. Jeff Tucker with the Canton Police.
The collision occurred near the northbound ramp onto Interstate 575.
Phillips was airlifted to WellStar Kennestone Hospital in Marietta following the accident, where he remained in critical condition on life support Tuesday.
Phillips was not wearing a helmet, Tucker said.
The accident is still under investigation.
His son from California arrived on Tuesday to be with his father, those close to the situation said.
Phillips was a real estate agent with Canton-based ERA Sunrise Realty and worked on the HUD buyer team, said David Moody, ERA Sunrise Realty broker-owner.
“(He) was a good guy. No matter what, he never got agitated, most of the time had a smile on his face and was kind to everybody,” Moody said.
Phillips, who was known as an avid biker, had a bicycle accident several years ago on Highway 20 where he was hit and later had to have several surgeries, Moody said.