The movers arrived at Barbara Ross’s apartment on the Lower East Side of Manhattan one Friday last month, grabbing bags of clothes and shoes, framed pictures and boxes of CDs. They carried the items downstairs and loaded them onto four long-framed cargo bicycles parked on Ridge Street.

As the number of objects atop the slender frames increased, the bikes brought to mind a train of pack mules preparing for a frontier crossing. Cargo, including a seven-foot-tall wood bookshelf, was cinched with thick canvas straps and crisscrossing bungee cords. Passers-by gazed curiously as the movers helped fit oddly shaped items onto a bike’s cargo platform.

When moving from one apartment to another, people in New York City have paid moving companies, loaded packed possessions into cars or rented vans, or even transported boxes and pieces of furniture on the subway.

Ms. Ross, 52, a video training manager who had just bought a co-op apartment near Union Square, hired members of the Cargo Bike Collective, a loose-knit group of people who own and ride the extra-long bikes, which they use for both paying jobs and volunteer projects.