"Skatetown, U.S.A." recycles all the standard ingredients of youth-craze quickies at a supposedly unique, glittering site: a beachfront roller-disco rink in Los Angeles.

The first of a threatened, er, prompised cycle of roller-disco romps, the movie is exuberant, inane and chastely conventional, despite the hints of easy pleasure that arise from the sporadic drug jokes and the persistent spectacle of nubile flesh on the verge of spilling out of shorts and halters.

Indeed. "Skatetown, U.S.A." is probably the most old-fashioned new movie in town -- no mean distinction a week after "The Runner Stumbles."

Skating supplants surfing as the fashionable athletic pastime among beach-party cognoscenti and disco is the reigning party craze. (Ah, if only Sam Katzman were still around to produce a generation-after sequel to "Don't Knock the Rock"! Maybe "Don't Get Down on Disco.")

It's Competition Night at Skatetown, U.S.A., the apocryphal mecca for L.A. skating freaks. The minimal plot concerns a rivalry that develops between the resident macho on wheels, Ace, leader of the hoodish Westside Wheelers and defending singles and doubles champ, and a cleancut challenger, Stan, a friendly, fearless blond muscle boy from the San Fernando Valley.

Given his virtuous character and the curiously prognathous, cartoonish good looks of Greg Bradford, the Allan Carr discovery cast as Stan, the ideal symbolic hometown for the straight-arrow hero would appear to be Tarzana. But screenwriter Nick Castle (yes, the son of the late choreographer) neglects to specify.

The conflict between Stan and Ace doesn't exactly throb with suspense or conviction. Indeed, it's an acknowledged joke. The ruthless, swarthy Ace turns out to have a dewy-eyed blond kid sister who looks like the perfect photogenic match for Stan and becomes his girl. Kelly Lang, cast as this virginal sis, was in fact Greg Bradford's real-life girl friend.

Meanwhile, Stan is given a rather sultry blond sister -- played by Maureen McCormack, a former juvenile regular on "The Brady Bunch" -- who is matched with Ace's first lieutenant, a facetiously vicious goon impersonated by a bearded Ron Palillo, the erstwhile Horshak of "Welcome Back, Kotter."

When Ace and his gang barge into the rink, hurling innocent customers aside, the treatment is too stylized to seem intimidating. Choreographer Bob Banas once danced in the chorus of "West Side Story." Like the Jets and the Sharks, the Wheelers have fare more reality as aspiring young dancers than ferocious young punks.

Since the movie would last about a reel if confined to the half-hearted enmity between Stan and Ace, the running time is filled out by comic turns and by musical and skating acts performed for the customers. The comics, frequently inserted during the production numbers to break up the monotony, sometimes well before any monotony has begun, include a couple of goofy vendors, a drunk, a codger, a spacey emcee, Nebbishy Little Newlyweds and a trio of indignant squares who loosen up after snacking on drug-enhanced pizza.

The comedy material tends to be more grotesque than amusing. Consider this sub-plot: Billy Barty is cast as the philandering dad of Flip Wilson who plays a double role as proprietor of the rink and his own mother. Mama turns out to a revival of Wilson's Geraldine character who confesses to the diminutive Barty that she's been just as naughty as he has, honey; in fact, more so. Even if the premise had undeniable comic merit, it would still be thwarted by the fact that Wilson and Barty don't look or act funny together.

I was also unamused by the gleeful treatment of skaters who are embarassed off the floor by Ace's henchmen. A contestant dressed like Pancho Villa is undermined with a dose of "itching powder," a substance I haven't encountered in quite some time. Another dressed like Uncle Sam is blinded by reflections so that he stumbles all over himself. Wilson cheerfully ushers him off with a joke about Gerry Ford. Most untimely and most unfunny.

As Ace, Patrick Swayze displays more talent than this production can conveniently handle. He has a lean, smoldering, potentially dangerous presence, suggesting a cross between the young Jack Palance and Andrew Stevens as he appeared in "The Fury," glaring psychokinetic daggers at the world. Swayze also appears to be a graceful, athletic dancer. The highlight of the show is his torrid pas de deux with the equally assured April Allen as Ace's moll. They look sensational gliding through an elegant adaption of the apache dance to roller skates.

Their number is the only dance sequence presented without interruption and visualized in a spacious, fluid, confident style. You can almost feel the director, cinematographer and editor rejoice at the opportunity to reveal more than they need to conceal.

Allen and Swayze's superiority on the dance floor contradicts the dramatic pretext so decisively that you wonder why a smarter pretext wasn't invented. Too much strain on the feeble exploitation brain, I presume.