The effort began in 2016 when Ms. La Fortune Reed rediscovered her old bicycle and started riding everywhere: to classes at Rutgers University in Newark, thrift shops and parks throughout the city.

One day, a man called out to her. Keep it up, he said. There aren’t enough girls on bikes.

Ms. La Fortune Reed scanned the streets and realized he was right. Studies backed up what her eyes told her: By middle school, girls are riding less than boys; by the time they grow up, women make up just 24 percent of riders in the United States. Her solution was Girls on Bikes.

She recruited Maseera Subhani and Jenn Made, friends from Rutgers who shared her love of cycling and for Newark itself; the idea of using bicycles to spread empowerment resonated with each of them.

The trio juggled full-time classes and part-time jobs to get the group going. Ms. La Fortune Reed interned with a local bike mechanic and learned how to repair bikes and build them from scratch. Ms. Made created a curriculum for school workshops. Ms. Subhani found graphic designers to make fliers and T-shirts, and reached out to other community groups to collaborate.