As public transit took a hit during the pandemic — ridership of subway trains alone declined 90 percent in New York City — cities began rolling out fleets of electric motor bikes, or e-bikes. And those bikes, it turns out, have skyrocketed in popularity, beginning to displace nonmotorized bikes in many places.

While e-bike sales are on the rise according to industry groups, they don’t account for the actual usage. Trip data from bike-share programs — a public system of shared bikes that charge a fee — may shed some light on their use.

An NBC News analysis of bike-share data from 11 of 13 cities that have comparable numbers shows that in May of last year, e-bikes accounted for only 11 percent of bike-share rides in cities surveyed, with 240,000 e-bike rides. Last month, they accounted for 38 percent of bike-share rides, ballooning to 1.4 million trips. The remaining 62 percent of rides were on conventional, nonmotorized bikes.

The data, provided by BCycle, Lyft and open data sources, shows that e-bike rides made up more than a quarter of bike-share trips in Philadelphia and about half of all bike-share rides in Minneapolis and Columbus, Ohio. In the Bay Area, e-bikes accounted for more than 70 percent of bike-share trips.

In some cities, e-bikes contributed to a post-pandemic bounce in bike-share usage. In Chicago, the number of bike-share rides in May increased from 338,000 in 2019 to 531,000 in 2021, with a third of those extra rides on e-bikes.

While bike-share programs are not new, the addition of e-bikes allows riders to easily reach speeds of 15 mph, or speeds typically associated with high-endurance riders. That’s because of an electric motor that accelerates the bike as the rider pedals, making it possible to commute longer distances in a short amount of time.

The increased speeds have also raised safety issues. The U.S. Consumer Product Safety Commission issued a report last year that said e-bikes accounted for 9 percent of micromobility injuries. "Micromobility" refers to transit devices such as e-bikes and hoverboards.

Samantha Herr, executive director of the North American Bikeshare Association, an industry group that advocates for increased use of bike-share programs, e-scooters and e-bikes.

Herr’s organization published a report in 2020 that showed e-bike utilization grew in 2019 and they were used almost twice as often as conventional pedal bikes in an average day.

“We see [bike-share] as a piece of the broader way that people are going to get around their towns and cities,” she said. “It connects people to transit from first mile to last mile. ... It’s also filled in transit deserts.”

Chicago tried to address those transit deserts last year when it introduced e-bikes to its Divvy bike-share program, which was part of a major expansion of the program, said Gia Biagi, the transportation commissioner for Chicago.

Divvy e-bikes accounted for 10 percent of all bike-share rides in August 2020, the month the bikes rolled out, according to bike-share data. E-bike usage climbed to nearly a quarter of rides in September, and as of last month, the bikes make up a third of the city’s bike-share rides.

Biagi said the rising popularity of the e-bikes was the result of several factors.

“Folks who might have felt uncomfortable being in a vehicle, then looking at the Divvy bike and say, ‘Oh, this is a great option.’ We also offered deep discounts at the height of the pandemic to really incentivize people with an alternative option if they were feeling like they weren't ready to take public transit,” Biagi said.