An officer from the Leeds North East beat team found drawing pins on the Meanwood Valley cycle path earlier today.
He had stopped to help a female cyclist whose tyre had burst after being punctured by a tack.
The officer then found further pins, including one which was embedded in his own tyre, and believes they had been placed there on purpose.
The Leeds Cycling Campaign group also said on social media that their members were aware of the hazard.
Scattering tacks is a disruptive tactic sometimes used by spectators at professional cycling events, including the Tour de France.