If the roller-disco nostalgia comedy "Roll Bounce" didn't have Malcolm D. Lee in the director's chair, it would be downright unwatchable.

Built on a sloppy, fill-in-the-blanks plot, it follows a group of rollerskate-crazy 1970s teens from Chicago's tough South Side as they're forced to migrate to a trendy North Side roller disco because their run-down local rink has been shuttered. This leads inevitably to a rivalry with hot-shot locals and a "skate-off" finale, and the story couldn't be more stale if the script itself were a dusted-off relic from the Jimmy Carter era.

But Lee has a gift for finding gold nuggets of personality and comedy in the tailings of over-mined plots. He turned 1999's contrived reunion/wedding flick "The Best Man" into a character-rich dramedy and exploited the stupidity of 2002's "Undercover Brother" for great laughs. In "Roll Bounce," he makes up for the shopworn, thoroughly predictable source material by punching up the comedy and hiring talented young stars to flesh out the stock characters.

Maturing kiddie hip-hopper Bow Wow -- whose dazzling charm also helped the childrens' basketball flick "Like Mike" rise above its script -- plays Xavier ("X" to his friends), the teenage rollerskating protagonist from the wrong side of the tracks. His buddies include Rick Gonzales ("The Rookie," "Coach Carter"), Khleo Thomas ("Holes," "Baadasssss!"), and gal-pal Jurnee Smollett ("Eve's Bayou"), each of whom provides genuine individuality and friendly smack-down humor in these supporting roles.

The movie is actually at its best away from the roller rink, when Lee can focus on the comedy that comes from these personalities, even as the elementary plot clunks along in telegraphed fits and starts about friendships and family struggles (Chi McBride is superb as his unemployed, recently widowed father). But X's rivalry with a ridiculous, arrogant, one-dimensional disco king nicknamed Sweetness (Wesley Jonathan) -- who comes complete with an entourage of fawning bimbos and sequin-attired toadies -- inevitably leads to a well-shot but rather anti-climactic showdown during a $500 contest to crown a king of the uptown rink.

And, of course, there's a love interest -- jawdroppingly gorgeous Meagan Good ("Eve's Bayou," "Biker Boyz"), who at age 23 is conspicuously older than teenaged Bow Wow.

While also overly self-indulgent at 112 minutes, "Roll Bounce" rises above its considerable flaws not just with likable characters and an amusing quick wit, but also through Lee's visceral sense of period nostalgia. Fueled by great skating, a great funk soundtrack, horrible clothes, and big afros, Lee plies the picture with flashback-educing touches of authenticity, like curfews that begin when the streetlights come on, AM/FM radio headsets with retractable antennae extending from each cumbersome earphone, and energetic split-screen dance sequences.

So while "Roll Bounce" may have one of the most shopworn, cliché-riddled, minimal-effort scripts of 2005, the end result is an entertaining Saturday matinee that's hard not to like.