Lincolnshire Police has named the motorcyclist who died at the scene of the A46 crash near Lincoln.
The motorcyclist is Phillip Neil Bolton, aged 53 of Welford Road, Wigston, Leicester.
A post mortem will be arranged shortly to establish the exact cause of death.
He died at the incident on the A46 southbound, near the Thorpe on the Hill flyover just before 10.50am on Easter Monday morning.
Police believe that from a group of nine bikers, three have been involved in the collision, possibly with each other while all were overtaking a tractor travelling in the nearside lane.
Philip Bolton was pronounced dead at the scene, whereas a 54-year-old rider was taken to Queens Medical Centre with suspected injuries to his back. He has since been discharged from hospital.
A 36-year-old also injured was taken to Lincoln County Hospital with a serious leg injury.
He remains in hospital but his condition is not thought to be life-threatening.
The investigating officers are appealing for witnesses to call the witness hotline on 01522 558855.