Allan Burns, 71, was last seen at around 3.15pm on Friday on the cycle path at Kilbarchan, heading towards Lochwinnoch in Renfrewshire.
He was reported missing by family when he did not return home.
Police Scotland said 80 people turned up to help with efforts to trace Mr Burns.
Concerns have been growing for the safety of Mr Burns, as he is without his medication and the weather is becoming colder.
Police are urging anyone with information about his whereabouts to contact them.