Police are appealing for spectators who witnessed the fatal crash during the final race of the Cock o' The North road race meeting at Oliver's Mount on July 22.
Police are particularly keen to speak to anyone who may have video footage of the incident.
Traffic Sergeant Pete Wood said: "Biking enthusiasts will have travelled from for and wide to watch the races, and it is them who I am appealing to for assistance with this investigation.
"Fan’s video footage could be extremely valuable in determining the sequence of events which led to the collision.
"It is vital that we establish what caused this tragic event and anyone who can assist us is urged to get in touch as soon as possible."
38-year-old Steve Hix from Holbeach near Spalding, Lincolnshire crashed at around 6pm and was pronounced dead on arrival at Scarborough District Hospital.