Officers are asking for anyone with information to come forward.
The incident reportedly happened shortly before 9pm on Wednesday 8 January, in Knightthorpe Road between Tennyson Road and Burns Road.
The victim had visited a shop in Knightthorpe Road towards Epinal Way and was making his way home when he was approached by a man on a bike who threatened him with a knife and told him to hand over money. The victim refused and the man left the scene.
The man was riding a bike and is believed to be aged between 18 and 20. He is around 5ft 5ins tall and spoke with a local accent. He was wearing a black, fleecy, zip-up hooded jacket and black jeans.
PC Rachel Healey, the investigating officer, said: “The victim has been left quite shaken by this incident.
“Please cast your mind back. Did you see anyone matching the description given in the area of Knightthorpe Road on the evening of 8 January? If so, then please get in touch.
“I would also like to speak to anyone who has CCTV or dashcam footage of the incident.”
Call 101, or send us a direct message, quoting reference 20*014850.
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