A 16-year-old boy was badly injured after being in collision with a motorbike in Kettering Road, Islip.
The teenager was cycling on the road from Thrapston to Woodford with a friend at about 10pm on Tuesday when the collision with a white Rieju Marathon motorcycle took place.
The teenager received serious head injuries from the collision.
Police would like to speak to anyone who may have witnessed the incident or has any information about it.
Anyone with information or who witnessed it is asked to call the Drivewatch Hotline on 0800 174615.