Stefan Forge was killed while cycling with a friend
It is believed the driver responsible may not have been aware of the collision.
Stefan Forge, 47, was killed on the A658 between Harrogate and Bradford near North Rigton, North Yorkshire.
Mr Forge, a microbiologist from Harrogate, was cycling with his friend Jonathan Wastling when they were struck by a vehicle at about 23.15 BST on Wednesday, 22 August.
Mr Wastling, 42, from Harrogate, suffered serious injuries but survived and is now recovering at home.
'Always smiling'
Despite extensive inquiries by North Yorkshire Police, including road checks, the driver involved in the accident has not been traced.
Mr Forge's brother, Adrian, said the family was still struggling to come to terms with the loss.
"The family is totally devastated. My brother always had time to listen," he said.
"He was always smiling. He will be sadly missed by everyone who knew him."
Unsuspecting driver
Mr Forge said his brother was a fit man who was a keen sportsman, keen on cycling and running.
"He had so many plans for the future but they have all been taken away from him now," he said.
"I would appeal to anyone who knows anything about this accident to contact police."
Farm contractors
Police believe Mr Forge may have been hit by a large vehicle such as a lorry and the driver may not have noticed the collision.
Police said a front spoiler from a type of Seat vehicle was found near the scene and officers wanted to trace the driver and eliminate him from the investigation.
As part of the police investigation 71 farms and agricultural contractors have been checked as well as plant hire and crane businesses.