Police are investigating a report of dangerous driving on the A169 between Lockton and Saltersgate which was received on Sunday.
Officers are appealing for witnesses who may of seen two motorbikes at the Hole of Horcum car park and then at around 11.45am travelling north along the A169 towards Whitby, to contact them.
Officers are particularly keen to trace the drivers of a number of Porsche cars, who are believed to have been travelling along that stretch of road that morning, either in convoy or to or from an event. They would also like to speak to anyone who may of captured dash-cam footage of the bikes that morning.
Anyone who saw the bikes or who has any information which could assist the investigation is asked to dial 101, select option 1 and ask to speak to Traffic Constable Mark Patterson.
You can also email Mark.Patterson@northyorkshire.pnn.police.uk. Please quote reference 12190099137.