Cops are cracking down on cyclists riding on sidewalks, issuing 43 summonses in Gramercy and Chelsea in the last month.

About 90 percent of those ticketed were restaurant deliverymen, police said. First offenders are fined $100.

Transportation Alternatives, a pro-bicycling group, hopes the police crackdown will change cyclist behavior.

“This is enlightened enforcement,” said Wiley Norvell, a spokesman for the group.

He called biking on sidewalks “one of the more dangerous behaviors out there.” John Doyle and Bill Sanderson