Bike helmets in Pittsburgh, the city that inspired a film about a bicycle race, have been banned for girls and pregnant women.
The city’s mayor, Bill Peduto, said the move was prompted by concerns about the impact on babies.
“Bikes are dangerous,” he said in a statement.
“We have not had a single fatality related to cycling in the last five years.”
But Peduto said the city had decided to keep the helmets on bikes to ensure that they would not pose a health risk to riders.
“There’s no question that if we have a helmet law, people will use it,” Peduto told reporters in the city.
Peduto’s announcement came as the city’s chief health officer, Dr Sarah Koller, said that her department had identified a “high number of cyclists” who were at high risk of being seriously injured or killed.
Pedutos bike ban is just the latest to hit the cycling industry in recent months.
In April, the European Union said it would impose sanctions on the bike industry over a crackdown on helmet use, while in October, the US state of Massachusetts imposed a helmet ban for women, and in November, a New York cyclist was killed in a crash after he was struck by a vehicle while riding his bike in the Bronx.
But Peduto said the new ban had been approved by a committee made up of city, state and federal officials.
Peduuto said he had consulted with the city council and was happy with the outcome.
“This is a big step forward,” he told reporters.
“But we still have to go to the state and the federal level and the states have to do the same.”
Peduto has said he has no plans to appeal the ban.