A man was targeted by a robber after he pulled up on his bike at the gates of a playground in Doncaster.
The 35-year-old was cycling home when he stopped near to the entrance to a children's playground in Waverley Avenue, Balby.
South Yorkshire Police said he was approached by a man who pushed him from his bike and grabbed his rucksack before running off.
The victim suffered minor facial injuries during the incident.
The robber was white, between 16 and 20 years old, around 5ft tall and of an average build with short, spiky hair.
He was wearing a bright blue Adidas jacket with black tracksuit bottoms and blue trainers.
A South Yorkshire Police spokeswoman said: "At around 5.30pm on Friday, November 24, it is reported that a 34-year-old man was cycling home when he stopped near to the gates of a children’s park on Waverley Avenue, Balby.
"He is believed to have been approached by an unknown male suspect, who assaulted the 34-year-old - pushing him from his bicycle.
"The suspect grabbed the man’s rucksack before running from the scene. The 34-year-old suffered minor facial injuries during the robbery.
"The suspect is understood to have been with a group of people at the time of the incident.
"Did you witness the robbery, or see anyone matching this description in the area at the time?"
Anyone with information should call South Yorkshire Police on 101, quoting 804 of November 24.
Details can also be passed to Crimestoppers on 0800 555 111.