Two thirds of the City Council is calling on Mayor de Blasio to include funds for bike-share expansion in his 2018 budget. Officials at DOT and Citi Bike operator Motivate have said subsidies will be necessary to expand bike-share citywide. But earlier research by the Department of City Planning indicates that the bike-share system could quadruple in size and reach many low-income neighborhoods before any operating subsidies are needed.

Citi Bike ridership is growing, and the system is set to expand to Harlem, Astoria, and Crown Heights this year. But it does not extend to many less affluent neighborhoods where it could be widely used, and there are no concrete plans to reach those parts of the city.

“We know the value that this great service brings to New Yorkers,” transportation chair Ydanis Rodriguez said at a press conference this afternoon. “Unfortunately, without city funding in this year’s budget, Citi Bike’s plans for expansion will come to a screeching halt. This will leave communities outside the Central Business District removed from what has become a great service.”

In a January 3 letter to the mayor [PDF], the 34 council members commend the bike-share network for “its values as an [transportation] equalizer in New York City” and call on de Blasio to “advance a plan…to achieve your stated commitment to expand Citi Bike to all five boroughs.” Their position is buoyed by recent polling from Penn Schoen Berland Research, commissioned by Transportation Alternatives, which found 71 percent of NYC residents want to see bike-share expand to all five boroughs.

In November, Motivate CEO Jay Walder and DOT Commissioner Polly Trottenberg told council members that a five-borough system would not be possible without city subsidies. Motivate did not reveal specifics about why its own finances are insufficient to support expansion.

Rodriguez, who organized the letter to the mayor, declined to discuss financial details at today’s press conference. He said that the administration should hammer out the details with Motivate, and know that it has City Council support if the agreement requires subsidies.

“We provide public subsidy so that subway and bus service is available throughout the city,” Council Member Brad Lander said today. “It’s just no different from Citi Bike. It’s become a piece of our transportation infrastructure.”

Blanketing the whole city with bike-share stations would cost about $400 million upfront, Motivate said in November, and such a system would need operating support. But many neighborhoods could be covered for less expense, and without large subsidies, if the expansion prioritizes denser, walkable areas in the Bronx, Queens, and Brooklyn.

Many streets beyond the current bike-share zone also lack safe bike infrastructure. The T.A.-commissioned poll found that 69 percent of voters think new protected bike lanes should accompany bike-share expansion.

“It’s irresponsible to expand Citi Bike without those life-saving safety improvements,” T.A. Executive Director Paul Steely White said.