Police have named the man who died after his motorbike crashed in Corby Glen as 37-year-old Mindaugas Mockus, from Spalding.
The accident happened on the A151 Station Road, just before the railway bridge, at about 10.50am on Sunday.
A police spokesman said the man was riding a Yamaha motorbike when he crashed and was fatally injured. No other vehicle was involved in the crash.
The spokesman added: “The motorcyclist was part of a group of three other motorbikes and officers would like to hear from anyone who may have witnessed the collision or saw the group. In particular they are keen to trace a woman in a silver Ford Focus estate with possibly an 08 or 10 number plate, who could be a potential witness.”
Anyone with any information should call the Lincolnshire Police Collision Witness hotline on 01522 558855.