A virtuous cycle

The training wheels have been off for a while: Citi Bike, the bicycle sharing system that debuted four years ago with unreliable equipment and wobbly finances, is pedaling confidently ahead without a penny of taxpayer subsidy. That’s thanks to the competent management of Motivate, under the stewardship of former MTA Chairman Jay Walder. Good going.

Now the blue bikes, once resisted, are in heavy demand. The Bronx, on the outside looking in, wants some. So does Staten Island.

The city should leap to meet the demand — provided taxpayers, who have lots of other priorities (cough cough subways in crisis cough cough) aren’t on the hook. Citi Bike can grow sustainably on its own dime, with a few adjustments.

What a difference a few years make. In 2013, Mike Bloomberg boldly launched the program with 6,000 of the big blue bikes in Manhattan south of 59th St. and a few neighborhoods around downtown Brooklyn.

It was good when it worked, but far too often the bikes weren’t there when you needed them. Balancing, as they call it, was a chronic complaint. Annual members were bailing rather than reupping.

Two and a half years ago, Mayor de Blasio smartly tossed the inept operators. In stepped Walder and Motivate, which also manage programs in cities across the country.

Performance is night and day. The smartphone app consistently works. Bikes are available, redesigned and in good repair.

The network has grown to 10,000 bikes, with presence now in many more parts of Brooklyn and Manhattan and Queens, soon to grow to 12,000.

There are now 130,000 annual members, as opposed to 80,000 before. And they are riding more often, taking an average of 120 trips a year, up from 80.

So what’s next? More of a good thing — without city subsidy.

Wisely rejecting calls in the City Council for public dollars to expand to more locations, Walder has offered City Hall a plan to deploy thousands more bikes to new swaths of Manhattan, Queens and Brooklyn, and to add service in parts of the Bronx and Staten Island.

What he wants in return is simple: To start, a second ad panel on the docking stations. Fine by us.

He also wants the city to forgo collecting what is supposed to be lost parking meter revenue. As this money, about $1 million a year, has never been collected, that should also be fine.

Last, he wants more flexibility on pricing options, now set at yearly, three-day and daily rates. Why not, say, hourly rates for tourists? Perfectly sensible.

Maybe what’s motivating Walder is the rise of potential competitors that aren’t tethered to docks. These bikes, now present in huge numbers in China, self-lock and can be picked and dropped off anywhere.

New York officials must enforce Citi Bike’s exclusive rights in the areas it serves. But what should be allowed in parts of the city beyond the Citi Bike map, where riders currently have no bike-sharing options?

We don’t pretend to have the answer to that question.