The New York City Police Department, with its 35,000 officers, has in recent years been on the front lines of the citywide decline in serious crime. It has protected visiting dignitaries like Pope Benedict XVI at events that drew thousands of people, and it has posted officers in foreign capitals to gather information on terrorism and trends that could threaten New York.

But the Police Department continues to be flummoxed by bicyclists riding together once a month.

The city took a tentative step this week toward fulfilling the dream of a certain kind of urban idealist, saying that it will explore the possibility of creating a bike-sharing program that could make hundreds or even thousands of bicycles available for public use.

“This is a really big deal,” said Wiley Norvell, a spokesman for Transportation Alternatives, an advocacy group for cyclists, pedestrians and transit riders. “In the realm of things you can do to boost bicycling in a city, bike-share is at the top of the list.”

The city asked companies and organizations interested in running a bike-sharing program to provide assessments of how it could work.

A similar program was started last year in Paris, using thousands of bicycles. A program with 120 bicycles was started earlier this year in Washington.

PARIS, Sept. 29 - Mayor Michael R. Bloomberg, on his first trip here since he took office, acknowledged the challenges of bringing home a popular Parisian bike rental program the administration is exploring, saying he was unsure it would translate to New York.

Noting challenges like roads damaged by seasonal changes, the lack of bike lanes, liability problems and the possibility that commuters would not want to carry helmets to work, Mr. Bloomberg said: "You try to see whether it fits, and some parts of it will, but it may very well give you an idea to do something totally different."

Under the program, which started in July, thousands of bicycles are docked along Paris streets, and customers can rent them after buying a membership ranging in time from a day (about $1.30) to a year (about $38). Members pay by the half-hour, with the first 30 minutes free. To discourage long rides, the fee rises from $1.30 for the second half-hour to $5.20 for the fourth.

Judging from the lines of empty consoles in the city center and the ubiquity of riders, even in the rain, the program has been a hit here, despite occasional technical glitches and a lack in some places of empty spots to return a bicycle. One official told Mr. Bloomberg that 100,000 people had signed up for yearly membership and that customers had taken more than 5 million rides.

Whether such a system could survive in New York, where bike theft is common, remains to be seen. Lionel Bordeaux, a press officer for City Hall here, said the fact that all fees were paid by credit card, and a roughly $200 charge for unreturned bikes, discouraged stealing.

A satirist dressed as a preacher and protesting what he called the Disneyfication of New York City was arrested Friday for harassing police in Union Square before the start of a monthly bicycle rally that the Bloomberg administration has been trying to rein in.

Bill Talen, who performs under the name Reverend Billy, said that he was arrested after trying to defend the cyclists' rights by reading the First Amendment to the police - through a bullhorn. The authorities said that he was arrested after repeatedly being told to stop.

Mr. Talen was charged with two counts of second-degree harassment. He was released without bail pending a court date in August.

"We were full of the holy spirit of the First Amendment," said Mr. Talen, who is in his mid-50s and was dressed like a big-tent evangelist, with a white suit and a dyed-blond pompadour. He sometimes spreads his message with the help of the Church of Stop-Shopping Gospel Choir.

In an interview yesterday, Mr. Talen defended his performance art. "New York City won't exist if we won't let creativity happen in public space," he said.

Mr. Talen said he was at Union Square to support the cyclists taking part in Critical Mass, a monthly ride aimed at promoting nonpolluting forms of transportation. Critical Mass riders gather the last Friday of every month at Union Square.