A man was mugged at knifepoint by a cyclist with black thick-framed glasses on a busy south London street.
The victim, who is in his 40s, was pushed to the floor on Greyhound Lane, Streatham, and attacked by a man who had been riding a mountain bike.
The mugger grabbed his cash but cycled off towards Streatham High Road when passers-by intervened.
Lambeth police are appealing for witnesses to the violent robbery last Friday at 9.30pm.
They are hunting for a stocky black man as part of their investigations.
Detective Constable Stuart Grover, from Lambeth CID, who is leading the investigation, said: "This was a violent attack on the victim where a high level of violence was used.
"Fortunately, the victim was assisted by local residents and was not seriously injured. It's important that we trace anyone who may have witnessed this crime in order to prevent further offences, and bring the offender to justice as soon as possible."
Anyone with information is asked to contact police on 101 or speak to Crimestoppers anonymously on 0800 555 111.
