It’s a head-scratching way to promote bike ridership.

Citi Bike’s social-media presence overwhelmingly shows riders pedaling without helmets in the face of a national call for laws mandating the lifesaving headgear.

The bike-share service’s Instagram account is packed with shots of smiling cyclists — sans helmets — riding as though they were out on a countryside jaunt rather than dodging potholes and taxi drivers on the mean streets of the city.

While New York law does not require bike-sharers to wear helmets, safety experts say Citi Bike still has a responsibility to set a good example for its riders, who have collectively taken up to 90,000 trips in a single day.

“The best practice for the use of a bicycle is to show a rider wearing a helmet, whether there’s a law in place or not,” said Alex Epstein of the National Safety Council.

“There is a significant responsibility among all members of the road ecosystem to promote proper relevant education.”

The National Transportation Safety Board last month recommended all 50 states pass laws requiring cyclists to wear helmets.

But of the 46 photos Citi Bike has posted this year featuring cyclists, 37 show riders without helmets, while just seven depict protected pedal pushers. The remaining two images show groups of riders with some helmeted and some not.

Still, the Lyft-owned service maintained that messages it posts on its app, bikes and station kiosks all promote safe cycling.

“Encouragement to riders to wear helmets is in multiple, conspicuous places throughout the physical and digital Citi Bike network,” spokesman Cory Epstein said in a statement.

The five boroughs have tallied more than two dozen cyclist deaths so far in 2019, including that of a Citi Bike rider, who was struck in April — the second fatality of a Citi Biker since the service launched in 2013.

Most pedal pushers polled at the foot of the Brooklyn Bridge in Manhattan on a recent weekday said helmets are a good idea — even though only a minority were actually covered up themselves.

“It may not be the difference between life and death, but if you get into an accident with it, hopefully it will be less traumatic,” said Frozan Sabeh, one of the few cyclists who was wearing a helmet.

“I think it’s necessary,” added Sumeja Tulic, 34, despite not wearing a helmet herself. “I am only going for a short distance and hoping that nothing bad will happen.”

Additional reporting by Lorena Mongelli and Aaron Feis