The incident happened in the Divis Road/Northumberland Street area of the city around 2 pm yesterday, Thursday, July6.
Detective Sergeant Wilson said: “A group of three men on quad bikes were approached by a male in his early 20s, wearing a black tracksuit and a black baseball cap.
“This male then produced a knife from his pocket and demanded one of the quad bikes.
“However, the quad bike rider was able to drive off, uninjured.
“We are appealing for anyone who may have witnessed this incident to contact detectives at Musgrave station on 101 quoting reference number 710 of 06/07/17.
“Alternatively, if someone would prefer to provide information without giving their details they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.”