By John R. Quain, The New York Times Co.

On the desolate streets of Manhattan during the bleak early days of the pandemic, Rosemary Sigelbaum found that riding a bicycle to work at Lenox Hill Hospital offered a desperately needed respite from the stress of 12-hour days witnessing the worst of the coronavirus’s frightening effects.

“It was quiet, and on my way home it gave me time to decompress,” Sigelbaum said of her commute between the Upper East Side and her home on the Lower East Side.

Those empty avenues of late March have given way to the city’s usual cacophony of traffic, just as more people are discovering the advantages of cycling to work: no crowded subways, buses or shared taxis. Bicycle companies have posted out-of-stock notices for the first time in years. Sales in May skyrocketed 103{3c6be4297db6c6dead22aac82e61edad92a520b73a55778b8446ff6b78406501} compared with a year earlier, according to the NPD Group, a research firm.

But as all those new bikers are discovering the joys of cycling, they’re also discovering the dangers of riding on two wheels, especially in cities.

Even before the pandemic, bicycle fatalities in New York nearly tripled last year, to 29, from 10 in 2018. This year, at least 14 people on bicycles have been killed. With more bikes plying the streets with cars, buses and trucks, there’s more pressure than ever to find ways to make the roads safer, for everyone.

The best safety measures are those that keep bicyclists and motor vehicles apart, advocates say. Many cycling advocates are trying to capitalize on the pandemic popularity of bicycles to push for more dedicated bike lanes.

It is “the primary method of addressing bicycle safety,” said Kyle Wagenschutz at People for Bikes, an advocacy group. Indeed, cities including Milan, Paris and New York have been adding miles of bike lanes this year, with more planned.

Still, bicycles and cars will have to get along, and safety researchers are increasingly looking to technology for answers.

Last fall in Turin — before that area of Italy became a pandemic hot spot — a wobbly cyclist skirted a line of parked cars on a jammed suburban street as a large sedan rapidly approached from behind. In the morning drizzle, the driver was focused on a four-way stop that was coming up. Suddenly, a warning graphic flashed on a display above the dashboard, indicating that a bicyclist was directly ahead, and the driver slowed to give the rider more room.

Such encounters are part of a future vision of bicycle-to-vehicle communications that could help prevent accidents. The Turin demonstration, supported by Fiat Chrysler and the 5G Automotive Association trade group, involved a 5G wireless program meant to illustrate the advantages of high-speed communications among cars, bicycles, traffic systems and city infrastructure. (This has an alphabet soup nickname, C-V2X, for “cellular vehicle-to-everything.”)