The bike boom is still resounding.

More people are now biking over the city’s East River bridges than pre-pandemic days — a sign that more new cyclists are trying out two wheels to commute into Manhattan as people return to the office.

According to recent stats from the Department of Transportation, 21,872 cyclists pedaled across the four spans on the average weekday this May — 4,715 more than in 2019, or an increase of 27 percent (numbers for March 2020 were lower due to the city’s lockdown). At the same time, subway ridership remains less than half of what it was pre-pandemic — more than 5.5 million people routinely rode the subway daily before March 2020; that number fell more than 90 percent to just 300,000 daily trips last April, and the system logged its highest number of rides last month with more than 2.38 million trips in a day, according to the MTA.

The new stats, along with the surge in Citi Bike ridership, are just more evidence that Mayor de Blasio, and whoever replaces him next year, must double down on building out more protective bike infrastructure to keep up with demand, advocates say.

“Every data point from bridge crossings to Citi Bike ridership continues to show that New York City is facing an unprecedented bike boom. As more New Yorkers choose to bike, our city has a responsibility to provide more protected bike lanes, including on our bridges, and bike parking. This is especially critical as New Yorkers head back to the office, and will rely even more on biking as a tool for commuting,” said Transportation Alternatives Executive Director Danny Harris.

?RECORD BREAKING NEWS? The results are in! With 743,751 rides including 5 days with over 100k rides, last week is now our highest ridership week ever! ? ?? ? ?? ?

— Citi Bike (@CitiBikeNYC) May 24, 2021

Last year, Streetsblog reported that the number of cyclists pedaling across the four bridges — the Queensboro, Brooklyn, Manhattan, and Williamsburg — on weekdays in October was up 30 percent compared to the prior October, while the number of people driving over during the same time period was down 13 percent.

And on local bike lanes, like the Brooklyn Waterfront Greenway in Williamsburg, ridership was up a whopping 222 percent.

On weekends, ridership is also up compared to 2019; this May, 16,669 people biked over the four bridges on the average weekend day compared to 12,271 in May, 2019.

But the sharp rise on weekdays is significant because it shows that many of those cyclists are likely new riders, choosing to commute to their office in Manhattan’s central business district by bike rather than subway, advocates say. And it won’t be until September when at least 62 percent of businesses expect their workers to return to the office, the Commercial Observer reported.

“Clearly bike riding is going up,” said Bike New York’s Jon Orcutt. “Some people are going back to the CBD, and some are doing it on bikes — many of those people probably didn’t used to bike.”

But with more riders comes more crashes, especially in places with the worst infrastructure. Injuries to cyclists across the city are up almost 40 percent compared to the same time last year, according to NYPD stats. And so far in 2021, at least four cyclists have been killed on the streets of New York City — one fewer than this time last year — but overall, the last 12 months have been the bloodiest of de Blasio’s tenure. The city hit 100 traffic deaths on April 31 — a grim milestone that is typically not reached until July, Streetsblog reported earlier this month.

The continuous growth in cycling across the city has prompted advocates to call for wider bike lanes, like on First and Second avenues, and had a hand in de Blasio announcing one of the most significant repurposing of space from drivers to cyclists since he took office — adding a lane for cyclists on the Brooklyn and Queensboro bridges, which have both become dangerously overcrowded, leading to crashes.