Police officers are appealing for witnesses after a sexual assault in Fairoaks Drive, Raunds.
The incident happened on Thursday, February 7, between 8.45pm and 9.05pm, when a woman was out running in the area.
As she ran, she passed a teenager on a bicycle who then changed direction, rode past her, grabbed her inappropriately and then pushed her to the floor.
The offender is described as white, in his late teens, wearing a black top with the hood up and carrying a white drawstring bag.
Anyone with any information should contact Northamptonshire Police on 101. Information can also be submitted anonymously to Crimestoppers on 0800 555111.