First you have to be a believer, enough to convince your ears that they're feet and can walk barefoot on glass. To be a believer, you had better be young, because the pulse is not only loud, but frenetic -- first-degree cranium-crushing. Later, of course, when many of the bands have gone the way of all flash, you can say you didn't know any better.

We're talking heavy metal, and you either love it or hate it. It's the Howard Cosell of popular music. IRON MAIDEN is kinda fun; you gotta give 'em that. Riding the crest of the late-'70s British heavy-metal revival, these belligerockers have established themselves as the reigning kings of bedlam bop. So what if Def Leppard caught America's fancy first: Maiden will follow in their sonic footsteps all the way to the bank. "Piece of Mind" is the quintet's most accessible album, though not its best (last year's crunchy-perfect "Number of the Beast" takes that honor). Taking its name from the medieval torture instrument -- the music is the modern equivalent? -- Iron Maiden celebrates all the cliches of the genre: speedy twin guitars that think with one Valium mind, pomposity of spirit, banality of ideas, misogynous/platitudinous lyrics (delivered by Bruce "Air-Raid Siren" Dickenson) and a minor mindscape of sci-fi swords and sorcery. Listen to the ponderous "Die With Your Boots On" or the scorching "Sun and Steel" or the attempted-epic "To Tame a Land" and you eventually have to make a choice: energy or content? One will excuse the other. Sometimes. Of course, how can you go wrong with a dynamite drummer named Nicko McBrain? FASTWAY is built around the frenzied guitar of Fast Eddie Clark, ex-Motorhead maniac who obviously still has an ax to grind. Not surprisingly, Fastway's motor has a familiar powerchord purr to it. CONEY HATCH is a Canadian quintet that took its name from a famous booby hatch. Their tendency is heavy rock- blues in the Whitesnake tradition. In both bands, there's not much evidence of any close encounters with originality; they rock by the numbers and amplify heavy metal's conventions to the point of distortion. The terrible thing is that the whole package is absolutely terrific live: That's when the power of heavy metal really envelops you, and no matter what you think, you tend to surrender. Maybe it's because you can't hear yourself think. IRON MAIDEN -- "Piece of Mind" (Capitol ST12274); FASTWAY -- "Fastway" (Columbia BFC38662); CONEY HATCH -- "Outa Hand" (Mercury 812 869-1 M-1), all appearing at the Capital Centre Saturday at 8.