Two teenagers threatened to punch a cyclist in order to steal his bike.
Detectives in Clacton are investigating the street robbery, which took place at about 3pm on Monday.
The victim, a 21-year-old man, was in West Avenue, when he was stopped by two teenage males who removed his hands from the handle bars and threatened him.
They told the victim to get off his bike, which he did out of fear, and then made off with the bicycle.
Police believe they know the identity of one suspect, but the other is described as white, medium build, aged about 19, with tanned skin and wearing a beanie hat and grey tracksuit with blue stripes.
The mountain bike is a chrome/aluminium framed Ammaco bike, with black handle bars.
Anyone with information is asked to call Dc Jo Mangham at Clacton CID on 101 or Crimestoppers on 0800 555 111.