A rider and pillion were taken to hospital after being ‘apparently blown off their bike by the wind’ on the motorway according to emergency services.
Two lanes of the M4 were closed for nearly three hours after the incident at around midday on Monday near Swindon, Wiltshire.
The female rider suffered a “potentially serious” head injury, ambulance crews said. Her male passenger received head and back injuries. Both are believed to be in the fifties. Neither is thought to be in a life threatening condition.
Ambulance crews said there were no other vehicles involved in the accident, between Junctions 15 and 16 eastbound.
A spokesman for the Great Western Ambulance Service said: “There were concerns that the woman rider had initially lost consciousness due to a head injury she suffered in the impact.
“She was placed on a spinal board and taken straight to the nearby Great Western Hospital, where she has undergone a CT scan for a potentially serious head injury.
“Her male pillion passenger was also collared and boarded.”
A Met Office spokesman said winds in the Swindon area were around 17mph at the time of the crash and reached a maximum of 25mph throughout the day. “It was reasonably strong but not that unusual,” he said.
The ambulance service spokesman said crews suspected the couple were blown off the bike based on “reports from passers-by who stopped to help.
“They suddenly seemed to swerve for no other obvious reason.”