MUSIC BOUNCES THROUGH Rockers like an old truck on the backroads of Jamaica, an unfaltering reggae rhythm riding over the rocks and potholes of life in Kingston. The jangling beat never stops, fighting for acceptance with as much persistence as the Rastas who sing and play it.

Very few recent films have been as successful as Rockers at integrating a collection of period music with worthwhile screen footage. American Graffiti did it for the 50s, Coming Home tried to do it for the 60s, and Saturday Night Fever is close as we dare come to a soundtrack for the 70s. Of these, Rockers most resembles American Graffiti, a film where the music weaves in and out of the story, and the story--what little there is--bobs and darts through the music.

The reggae in Rockers (which features Peter Tosh and Burning Spear, among others) seems noticeably contemporary. It slowly unveils a political awareness less violent than Bob Marley's recent activist songs; and it feels more polished, more heavily produced than traditional Rasta music. A guitar, a bongo, and smooth, taffy-flavored voices don't appear to be enough anymore. One introduction sounds remarkably similar to several measures on Elvis Costello's recent album. And a tuxedoed concert performer carries himself like Barry Manilow onstage. These isolated moments don't detract, however, from the music's mirthful, sensuous beauty.

Rockers' predecessor, The Harder They Come, has a tiny mythic quality. It beats one song into a sandy grave but maintains a quick, urchin-like pace that never gets lost in the narrow, winding streets of Kingston. Rockers, simpler and less violent, doesn't show as much of the city, sticking primarily to the Rasta neighborhoods where life is slower.

Slower but more colorful. Red, green and yellow wash across the screen, twinkling from lapel pins, blaring from walls, or striped on crazy-cocked hats. But red, green and yellow soon appear as bland as black and white. Dressing like high-schoolers on clash day, the Rastas dazzle us in an untamed chorus of shimmery blues, violent purples, bold oranges and delicious browns. The colors and clothes take on their own life, choreographed and balanced like a palette.

With their strangely lilting English and extraordinary heads of hair that would put Bo Derek to shame, the Rastas never seem to stop dancing, laughing, singing or arguing to a secret rhythm. Rockers often goes to great lengths to reinforce stereotypes about poor Jamaican Blacks. Here are the watermelons, the ganja, the gambling, the be-bop rejection of authority, the broken homes, and the collective hatred of The Man, whomever he represents.

Leroy Horsemouth Wallace plays himself in the lead role with the shuffling nonchalance of a heroic anti-hero who knows things will work his way. He is not particularly attractive with a zig-zagging beard and untamed hair that he buries under foppish hats. But he steps stridently when he is angry, bends his joints with a marvelous fluidity when he is gleeful, and rarely ceases wriggling long enough to eat.

Horse specializes in conning his friends, trading his superb drumming talent for money and favors. Unhappy with life as a studio musician, he buys a motorcycle in order to sell records to shops in Kingston. When Mafia hoods steal his bike, then beat him, Horse decides it's time to exact revenge from rich Mr. Big, who happens to have a beautiful daughter named Sunshine. It's all very silly, of course, and it concludes with the same moral as any Robin Hood fable.

Rockers has less political ambition than The Harder They Come, and its cinematic style is less frenetic than the older film. The photography is smoother, more obviously professional. Bafaloukos directs with long, moving takes that wind around corners and travel through doors with a rare, natural sense, as if he were shooting a fancy documentary. Accordingly, he uses a minimum of reaction shots, and avoids montage nearly altogether until a marvelous sequence that shows Horse's friends assembling for the big rip-off. The actors match the camera style perfectly. They seem too natural to be acting, each word and movement appearing realistically in place.

Bafaloukos also has a terrific sense of humor that pops up most often when his camera captures the white tourists to Kingston. One idiotically chic couple (he wears an Andy Warhol Interview T-shirt) lock the keys in their car and have to hire a Rasta locksmith. But the clincher comes earlier, at a club restaurant where Horsemouth's band plays fast-paced reggae. A bewildered blond tourist turns to his young bride and exclaims, "This isn't calypso!"