DIVE, THEY SAID Rollins makes a leap of faith.

Typical of a music doc, Paul Rachman’s American Hardcore struggles to balance exposition with insidery analysis. A painstaking history of early-to-mid-’80s hardcore punk, the film dissects the music’s evolution and cultural impact, while detouring at will into well-worn background material for newbies. But if this adaptation of Steven Blush’s book of the same name doesn’t really work as 101, it’s packed with juicy insights for the die-hard fan.

After a boneheaded “Reagan sucked” intro, Rachman launches into an engrossing breakdown of the music’s regional epicenters. The suburban angst of the L.A. punks contrasts starkly with the enlightened aura of their D.C. counterparts and Texas’s out-and-proud provocateurs. Though many of the anecdotes have already been canonized, it’s still great to watch Minor Threat’s Ian MacKaye describing the finer points of hand-cut record sleeves, and a surprisingly dorky Henry Rollins recounting his leap from ice-cream scooper to Black Flag frontman. Nevertheless, the film sags beneath a glut of bite-size clips. While it’s admirable that Rachman wants to include every band that ever played an all-ages show, he might have listened to his talking heads, who unanimously posit Bad Brains and a few others as hardcore’s true titans, and weighted screen time accordingly. Still, as an audiovisual zine, the frantic film does right by its DIY heroes. (Opens Fri; Angelika.) — Hank Shteamer