A boy, aged 13, was threatened by a man carrying a knife who then stole his bike.
The teenager was pushing his off-road pit bike along Upper Wortley Road, Thorpe Hesley, when he was approached by two men, one of whom was carrying a knife.
South Yorkshire Police said the men ‘threatened’ the youngster before stealing his bike.
One of the robbers, who had the knife, was white, 6ft tall, in his late teens and was wearing a black and red Nike body warmer and a face covering.
A South Yorkshire Police spokesman said: “At about 9.25pm on Monday, March 14, it is reported that a 13-year-old boy was pushing his off-road pit bike along Upper Wortley Road when he was approached by two men unknown to him.
“The victim was not injured but has been left shaken by the incident. The two men then rode away on the stolen bike along Droppingwell Road towards Shiregreen.
“The bike is black and white and has a distinctive ‘Monster’ energy logo on the frame and tank.”
Officers investigating the incident have released a CCTV image of a man they believe could hold vital information.
Anyone who recognises him should call police on 101 or Crimestoppers on 0800 555111.