The Breeders, Shepherds Bush Empire, London

Kim Deal is a lesson in how seeming to have rock'n'roll in your bloodstream can count for so much more than merely making it. In the Pixies, writing a few songs, playing bass, occasionally singing sweetly and fiercely grinning at the whole experience won her a generation of fans. While her sometime Pixies bandmate Black Francis huffed and puffed his way through hundreds of solo songs, she marked the grunge era with The Breeders' one hit, 1993's "Cannonball".

The only two subsequent albums have offered a spectral version of songcraft. The canyon-wide gaps between albums have often been filled by headlong hedonism, alongside fellow Breeder, twin sister and debauchee Kelley. But tonight, they seem a memento of grunge's more positive times, before heroin and Kurt Cobain's suicide. Watching these burly, long-haired women good-naturedly neck beer, you are also left to think that few female-fronted bands have slouched so far past their gender roles. "Cool As Kim Deal", the Dandy Warhols song named a song. And not many are.

Over the course of a 90-minute set, though, you have to engage with her music, too. The immediacy and barely there structure, which is its charm, could do with more tunes to keep you hanging in. The songs from Last Splash stand strongest. "No Aloha" is built on sedated, slurred Pixies chords, with crushing lines such as "Motherhood means mental freeze" brought to a halt after barely two minutes by an air-raid siren. "Cannonball" is greeted as a last chance to hear one of grunge's great, bucking riffs. "I Just Wanna Get Along", sung by Kelley, attacks Francis's ego and acidly predicts Cobain's end: "If you're so famous, why aren't you dead?"

New album Mountain Battles is also heavily featured, and its atmospheric strengths are apparent. "Here No More" could be an authentic Appalachian death song, sung by the Ohio Deals like proud hillbillies. Country music suits Kim's voice, as on the motel back-road lament "Drivin' On 9".

Mostly, though, this gig is built on the sisters' goofy charm. It's never certain whether Kim's fixed grin comes from ceaseless pleasure or nerves. When Kelley stiffly folds her hands behind her back for "Regalame Esta Noche" (in Spanish, which she does not speak), it's certainly the latter. Her singing, too, is sometimes strained, making their harmonies sweet and sour. This is all close to rock's unruly purpose. But you can't help feeling that the Breeders get by too much on grins and good will.