A new biker gang is roaming the streets of Richmond Hill, Queens. This crew of mostly teenagers can be seen riding along 103rd Avenue just west of the Van Wyck Expressway. The bikes roar, but the booming sound has nothing to do with engines — because there are no engines. They are ordinary bicycles, not motorcycles, although these contraptions look and sound more like rolling D.J. booths. They are outfitted with elaborate stereo systems installed by the youths.

“This one puts out 5,000 watts and cost about $4,000,” said Nick Ragbir, 18, tinkering with his two-wheeled sound system, with its powerful amplifier, two 15-inch bass woofers and four midrange speakers. It plays music from his iPod and is powered by car batteries mounted on a sturdy motocross bike.

The riders are of Guyanese and Trinidadian background. In those countries, turning bicycles into rolling outdoor sound systems is a popular hobby.