The incident happened at 4.30am on Friday June 24 as the 29-year-old victim was making her way to work, off Fountain Road in Hull.
The woman was approached by the group who demanded her mobile. When Sse refused to hand over the phone the suspects grabbed her Muddy Fox white bicycle with a black and white seat and threatened her.
She was then pushed into a bush. She her unhurt but shaken.
The suspects are described as being white and aged in their mid to late teens. The man with the knife was about 17 years old, 5ft 6ins tall, skinny build, wearing light grey tracksuit bottoms, black jacket with a hood and a black bandana over half his face.
The second suspect was younger, possibly aged 14, with a baby face, 5ft 3ins tall and skinny build with short, brown hair. He was wearing grey tracksuit top and bottoms.
The third was 5ft 6ins tall, skinny build, with short hair and wearing a blue and black jacket and black jogging bottoms.
Detective Sergeant Matt Grantham said: “While the victim in this incident was not injured, she was very distressed by her experience and this group of youths clearly need identifying and bringing to justice.
“The suspects are all thought to be in their teens and I would appeal to parents; if they recognise the descriptions and think their son may be involved, please contact police and let us deal with them.”
Anyone who knows about this robbery, those responsible or the whereabouts of the stolen cycle, is asked to call 101 referring to log 47 of June 24 or Crimestoppers on 0800 555 111.