For all the talk of hot new garage-rock bands making their way out of expensive rehearsal spaces in gentrified New York City neighborhoods, this year's most crucial artifact of scrappy guitar-bass-drums friction is the sixth album from a Portland-based band that, as its album artwork has it, practices in a tiny basement with mattresses nailed to the walls. One Beat, the latest from post-riot-grrrl rockers Sleater-Kinney, probably would have taken that cake if the band had just gone about its business in its normal way; few musicians have mastered the art of making personal strife ring with urgency like singer-guitarists Corin Tucker and Carrie Brownstein and drummer Janet Weiss. (The Wu-Tang Clan at its best and least paranoid, maybe.) But nothing charges a great punk-rock band like a sociopolitical calamity, and 9/11 seems to have given S-K an extra blast of purpose this time around: "Far Away," new mom Tucker's semiautobiographical account of that morning, one-ups much of Bruce Springsteen's The Rising in terms of emotional oomph; "Combat Rock" asks a couple of questions of "dirty Uncle Sam"; "Step Aside" wonders why we don't "shake a tail for peace and love" over a groove that makes it impossible not to. The songs boast lots of new sounds, too--juicy keyboards, fancy backing vocals, kicky formal tweaks--but they'll give you chills at the Gypsy Tea Room on Friday night because they're not (entirely) about riffs.