Plain clothes officers tasked with patrolling Abronhill on Saturday arrested two cyclists whose conduct on Oak Road gave cause for concern.
Police saw a 46-year-old woman fall from a bike and then struggle to maintain her balance around noon.
The officers approached her and stressed they were police officers who were detaining her under the Misuse of Drugs act - after they saw her try to conceal an item in her trouser pocket, which turned out to be heroin.
In a fresh development, a 36-year-old male cyclist hoved into view and he too was stopped by the officers - who then identified themselves.
The man was also found to be in possession of a substance which also tested positive as heroin.
Reports on both these individuals have been sent to the procurator fiscal.