Yeah Yeah Yeahs, Forum, London <!-- none onestar twostar fourstar fivestar -->

Any band touting designer handbags on tour are in danger of being viewed as fashionistas rather than a serious rock outfit, and female fans in the audience tonight ape the singer and style icon Karen "O" Orzolek's dress sense, with bold patterns and angular haircuts. But it's apparent that there is more to the New York trio than style statements as soon as they arrive on stage.

Orzolek may wear a silver dress with a red hood covering her face (later, she'll don a diaphanous, multicoloured cloak), but her bandmates deliver an equally colourful sound, even if they wisely prefer all black to her space-age outfit. The drummer Brian Chase's heavy patterns come from the bottom of a well to fill the theatre, while Nick Zimmer's guitar crunches purposefully, and he remains unsurpassed in that odd combination of tight playing and dirty edges.

The Yeah Yeah Yeahs' current album, Show Your Bones, is a more measured affair than its predecessor. While 2003's Fever to Tell is densely packed with blues riffs and punk-funk rhythms, the new record brings in stately tempi and spacious arrangements - though the songs do sometimes fall flat.

Orzolek's yelping vocals, somewhere between Siouxsie Sioux and Joan Jett, have not changed. Her particular talent is to devise a serviceable chorus from "Uh, uh, ow", though after a while you long for a more informative delivery. At previous shows, she has writhed on the floor in ecstasy; now, voguing her way from one side of the stage to the other, she restricts herself to elegant movements that are part modern dance and part t'ai chi.

Maybe it is the uncertain nature of Show Your Bones that holds her back. Their earlier material benefits from a fluid dynamism that is sadly lacking on the new record, even with a multi-instrumentalist on hand to fill in the gaps. The last single, "Gold Lion", is propelled by a powerful riff but goes nowhere. Quieter numbers rely on unsettling moods that the band find impossible to recreate live.

So, older material provides a welcome break. Zimmer has yet to surpass the alternating delicate strands and punishing buzz-saw sounds of "Maps", and it's a reminder that Karen was better off when writing direct lyrics rather than the woolly metaphors that pepper Show Your Bones.

Despite this, "Honeybear", carried by a martial beat, is one of the harder songs from the album that fares better tonight, along with the Chilis-tight funk of "Phenomena". The highlight from the new album, though, is the next single, "Tried to". It's a lovely, plaintive, country-tinged number, in which Orzolek shows that she can hold a tune. Led by an acoustic strum, it is a reminder that she and Zimmer were once a folk duo, and it ends in a triumphant Can-meets-bluegrass stomp. If Orzolek's next look involves gingham and cowboy boots, no one should be surprised.

Touring to Sunday ( www.yeahyeahyeahs.com)