A 14-year-old boy was approached by two men on bicycles in Northampton before making a getaway.
The incident happened between 4.15pm and 4.30pm on Monday, November 13, when the teenager was walking along Far Cotton Road towards Asda on London Road.
Two males on bicycles approached him and demanded money and his phone. The victim was able to run away and the offenders rode off towards the bridge over the River Nene River.
A spokeswoman for Northamptonshire Police said: "The first offender is described as white, about 5ft 5in with a diamond stud in his left ear.
"He was wearing a grey hooded top and was riding a green and yellow mountain bike which was covered in mud.
"The second offender was mixed race, about 5ft 8in with short, black hair in a box cut style. He wore a grey hooded top and was also riding a bicycle."
Witnesses or anyone with information about this incident should contact Northamptonshire Police on 101 or Crimestoppers anonymously on 0800 555 111.