For years, community leaders in the Upper East and West sides have been complaining about deliverymen who ride bicycles on sidewalks, run red lights, and generally menace pedestrians.

“The cyclists hit people left and right and just keep on going,” the president of the 20th Police Precinct community council on the Upper West Side, Sam Katz, said. Ms. Katz and other leaders are counting on a new law that takes effect Thursday to help address the problem. The law, passed in March, requires restaurant managers to provide their deliverymen with safety equipment such as helmets, bells, and headlights. It also obliges restaurant managers to hang up posters — written in both English and the language spoken by the deliverymen — outlining the rules of the road for cyclists.

Deliverymen on bicycles irk residents on the Upper West Side so much that they are the no. 1 complaint heard by the 20th Precinct there, Lieutenant Biagio Carbone said.

“Every community board meeting, they’ll ask us, ‘How are our bicycle summonses going?'” Lieutenant Carbone, who has worked in the 20th Precinct and the 19th Precinct, on the Upper East Side, said. The abundance of restaurants that deliver in the two precincts makes the areas the worst in the city for reckless cyclists, he said.

“People are running a business and serving the community, which is fine, but they need to understand the rules,” Lieutenant Carbone said.

Last year, the 20th Precinct handed out 1,165 summonses to bicycle riders. Officers are on pace to increase that number this year, handing out 865 as of July 15, he said.

The city’s Department of Transportation is offering posters for the new law in Chinese, Russian, Korean, and Spanish.

“I think [the law] will certainly be helpful,” a spokeswoman for the Department of Transportation, Molly Gordy, said. “Who knows how many are aware unless you are certain that you’ve made them aware.

But almost all restaurant owners and managers interviewed for this story had not heard of the law. Some shrugged at the idea — they could not control the habits of their deliverymen, they said.

“I explain it to them 1,000 times,” the manager of Bagels and Co. at Amsterdam Avenue and 79th Street, Ronnie Wachsler, said. The deli’s deliverymen receive summonses from the police almost every week for breaking traffic laws, he said.

“Riding on the sidewalks, I agree it’s a problem,” Mr. Wachsler said. “But delivery guys in general, the faster they make a delivery and get back, the faster they make another one. Time is of the essence.”