After a 17-year-old died in Manhattan last week while riding an electric bike, there have been growing calls to crack down on motorized devices in the city.

The teenager, Gabriel Nacato, was riding a Deepower electric bike without a helmet and crashed into an S.U.V. These high-speed bikes are illegal on city streets, but many New Yorkers use them to get around.

Now, leaders in the City Council are pushing for a series of changes to improve safety for electric bikes and scooters, joining a national conversation over a rise in crashes.

Here’s what to know about the rules for electric bikes and scooters in the city.

Which devices are legal?

Several types of electric bikes and scooters are allowed, including “pedal assist” e-bikes that give cyclists an extra boost and other models that have throttles.

Citi Bike, the city’s bike share system, has a fleet of 15,000 gray pedal-assist electric bikes, which Mayor Zohran Mamdani has been spotted using.

Stand-up electric scooters are allowed if they are under 100 pounds and have a maximum speed of 20 miles per hour. Lime, the scooter company, rents electric scooters in the Bronx and Queens.

All e-bikes and e-scooters sold or rented in the city must meet industry safety standards.

Many models are banned, including electric bikes that have a motor of more than 750 watts or that can travel over 25 m.p.h.

Faster mopeds, or e-motos, are sometimes marketed as e-bikes or e-scooters, but they are in a separate legal category with additional regulations, including requiring a license and registration with the Department of Motor Vehicles.

There are also numerous other powered devices navigating the city’s crowded streets, from unicycles to homemade skateboards, many of which are illegal.

What are the rules for riders?

The speed limit for e-bikes and e-scooters is 15 m.p.h.

Riders must be at least 16 years old, and are required to stay off sidewalks, follow traffic rules and use a bike lane if one is available. They are also encouraged to wear helmets and to yield to pedestrians.

There are separate regulations and safety training resources for delivery workers.

Earlier this year, Mr. Mamdani ended criminal enforcement against electric bike riders for low-level traffic offenses, though the police are still issuing civil summonses. The mayor said he was concerned that bike riders were facing criminal charges for violations like ignoring a stop sign.

Now some are calling for tighter regulations, including a group that sued Mr. Mamdani over ending criminal enforcement. After the 17-year-old’s death in Manhattan, the group said that the city needed a “holistic framework” of regulations and that bikers “routinely flout the law with no fear of recourse.”

Which vehicles are the most dangerous?

Fatal crashes often involve high-speed devices.

When two men were killed in May in a crash on the Queensboro Bridge, one of them was riding an illegal Teverun Blade stand-up scooter that can reach 53 m.p.h. A man who died in Brooklyn in May was riding a Cleytro scooter that can travel up to 55 m.p.h.

The illegal electric bike involved in the crash in Manhattan, a Deepower QS7, can go 30 m.p.h. It is advertised on Amazon as an “adrenaline-packed riding adventure” and sells for more than $650.

Citi Bike riders have been involved in relatively few fatal crashes, even as ridership has soared to nearly 5.5 million trips per month. The company said that roughly 72 percent of trips are now taken on e-bikes, which cannot travel over 15 m.p.h.

There were two fatal Citi Bike crashes last year and one so far this year, the company said, noting that last year’s crashes were “dooring incidents” in which a driver opened a car door into the path of a cyclist.

Have there been more crashes this year?

Traffic deaths overall are at record lows in New York City, but there has been a rise in crashes involving electric bikes and scooters this year.

Nine people have died using stand-up electric scooters as of July 30, compared with five deaths during the same period last year, according to the city’s Transportation Department.

Eleven people have died using electric bikes this year, compared with eight during the same period last year.

How could the city improve safety?

The city has seized thousands of illegal bikes and scooters and warned stores in the city not to sell them, but it has been more difficult to stop online retailers.

The city could require helmets, though officials have been reluctant to do so, fearing that it could stall the growing enthusiasm for cycling by hampering impromptu trips.

Some experts have called for wider bike lanes with room for both slower pedal bikes and electric devices.

The City Council is considering a series of bills to address e-bike safety, including by potentially increasing enforcement. But Julie Menin, the Council speaker, does not support a local version of Priscilla’s Law, a state bill that would require riders of electric bikes and scooters to register their vehicles and have license plates.

After the crash in Manhattan last week, Mr. Mamdani said he was focused on street infrastructure that would improve safety for cars, bikes and pedestrians.

“We know that oftentimes the absence or the presence of infrastructure is the determinative factor,” he said.

Officials could also seek to better inform the public about how to use such devices safely. When lithium-ion batteries in electric bikes started a series of deadly fires in recent years, the city ran a public education campaign about the risks of storing the batteries indoors. Deaths from battery fires have dropped.

Letitia James, the state attorney general, last month issued a consumer alert that warned about selling or operating illegal vehicles.

“No one should have to fear for their lives when crossing the street, and I encourage New Yorkers to follow the law and report those selling illegal e-bikes and e-scooters to my office,” Ms. James said.