A documentary by Bing Liu. Rating unavailable

There’s a heavy, hollowed-out kind of hope at the heart of this on-the-fly exercise in visual diary-keeping that says as much about money as it does about the boys who grow up before your very eyes.

The first of two movies about skateboards getting their release this month, Minding the Gap trades Skate Kitchen’s sharp all-girl crew for a posse of troubled dudes from Rockford, Illinois, dubbed one of the most dangerous midsized towns in the Disunited States.

“This place just eats away at you,” says Keire Johnson, the only African-American and the most instantly likable of the pals profiled by talented first-time filmmaker Bing Liu, who started videotaping his skater scene while still in middle school. Thus, we are also able to watch the blandly handsome Zack Mulligan age from voluble, bright-eyed Anglo preteen to beer-besotted lout, doomed—alongside high-school sweetheart Nina and their luckless baby—to repeat the cycle of violent unrest he grew up with, in their huge, now-dilapidated houses.

The gap being minded here has to do with income, of course, and also the distance between childhood and being an adult. “We still have to fully grow up,” one says early on. “And it fucking sucks.” The F-bombs flow as freely as the Pabst Blue Ribbon in this Rust Belt wasteland, and you can see childlike consternation on the boys’ faces as they struggle to give more complicated answers to Bing’s increasingly frank questions. The gap in education yawns menacingly too.

It takes a while for quiet, scrawny Bing (who now lives in Chicago) to come out from behind the camera, mainly to address his Chinese-born mother about the abuse they both suffered at the hands of his American stepfather, now long gone. Keire’s volatile dad is also absent, but the kid somehow remains cheerful through everything, and eventually packs up his boards and musical gear to start a new life in another town, leaving Zack behind.

Remarkably, all three—a multiethnic microcosm of American malehood—keep improving their skating skills, offering glimmers of curb-hopping freedom unburdened by doubt, place, or history. Painted on the topside of one of Keire’s decks: “This Device Cures Heartache.” As it happens, the words were put there by Zack.