The broad daylight attack happened in Peterborough, Cambs yesterday, police confirmed.
The victim, who was in his 20s, was rushed to hospital with serious injuries after being stabbed twice in the back.
A spokesman for Cambridgeshire Constabulary said they were called at about 4.15pm to reports of violence at Town Bridge, outside Charters Bar and Café.
The victim, who is in his 20s, was on a bicycle when he was approached by a man who asked him to hand over the bike.
When he refused the victim was punched and pushed away from the bike before two other men approached him from behind.
It was at this point that one of the group stabbed the man twice to his lower back before they ran off towards Bridge Street and the city centre.
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“I would urge anyone with information about the incident to get in touch and provide as much detail as possible.”
In an earlier statement, a Cambridgeshire Police spokesman said: “Emergency services were called to Town Bridge, Peterborough at about 4.15pm yesterday (October 19) with reports of a violence.
“A man in his 20s suffered two stab wounds and was taken to hospital with serious but not life threatening injuries.
“Anyone with information is asked to contact police on 101 quoting reference 325 of October 19.”
A cordon was in place while emergency services attended to the incident.