A motorcylist living in Spalding was killed in a crash on the A151 on Sunday.
Mindaugas Mockus (37) was riding a Yamaha motorbike when he was fatally injured in the single-vehicle collision at Corby Glen.
The incident was reported at 10.52am and happened on Station Road, just before the railway bridge.
Mr Mockus 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 is asked to contact the Lincolnshire Police collision witness hotline on 01522 558855.
