The incident, in Motherwell, happened around 1am on Thursday January 16.
The victim was pushing her bike over the crossing when she was approached and threatened by two other women. She handed over some money and was then forced to go to a cash machine in Bellshill Road and withdraw a further sum of money.
The first suspect is described as 5ft 6ins, aged in her mid-40's. She was wearing a pink baseball cap with diamantes on it and a pink jacket.
The second suspect is described as 5ft 5ins, with black hair tied back in a ponytail, and also aged in her mid-40's. She was wearing a black jacket, blue jeans and trainers.
Detective Constable Graeme Stoddart said: “Fortunately the woman was not injured but she has been left very upset by what happened.
“I would urge anyone who saw what happened or recognises who was involved to get in touch with police. I am also keen to speak to anyone who was in the area at the time and may have dash-cam footage that could help with our enquiries.
“If you have any information please call Police Scotland on 101, quoting incident 1639 of Thursday, 16 January, or make a call anonymously to the charity Crimestoppers on 0800 555 111."