Five motorcyclists who were caught riding at speeds of up 155mph on the A47 at Trowse were on their way to a track day.
Police said the three men and two women were stopped by an officer on an unmarked police motorcycle at the A140 junction at around 9am on Sunday, August 6.
All five had been riding high-powered sports bikes, and one was spotted undertaking a car at more than 100mph.
They told the police officer that they were going for breakfast and then heading to a track day.
PC Mark Carter said they were all reported for traffic offences and will likely face court action.
He added: 'Although motorcycles can be enjoyable we would ask all riders to be responsible and ride safely and within speed limits.'
A Twitter post by the Norfolk and Suffolk Roads Policing team said: 'five bikers this morning decided to start their track day early. 'Crazy speeds over 150mph and undertakes on A47 are mad risks.'
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