The Forum, London

You can't tell the tale of black music over the past 30 years without beginning with Martin Luther King. Since the mid-Sixties, black music's most arresting moments have always had political convictions. A million men march - and pick up Marvin Gaye, Curtis Mayfield, Stevie Wonder, Gil Scott Heron and Public Enemy albums on the way home.

But even the most ardent of social reformers have probably dithered over orchestrating their efforts to Michael Franti's brow-beating rap. While the icons above by and large sweetened the black consciousness pill with incandescent soul and irresistible funk, the San Franciscan has been guilty of dishing up his undeniably acute diatribes with the musical equivalent of cod liver oil.

In both name and sound, his previous outfit, The Disposable Heroes of Hiphoprisy, came on like a sociology thesis with a drum machine. , though, Franti's latest group, at least look like they want to send you back to the history books humming a few tunes.

That's not to say that Franti doesn't bang his drum, it's just that he knows that the result has to be something you can shake a leg to as well. Home, from 1994, squared up to the spectre of Aids in the US black community and this year's Chocolate Supa Highway bent ears about the iniquities of the prison system, but at least did so with increasingly palatable swingbeat and laid-back hip hop settings.

Live, in fact, Franti's revolutionary conscience looks to have been temporarily deposed by a good-time junta. His one serious speech to the audience on death seems touchingly out of kilter with his earlier admonition to legalise "the 'erb", and anyway it seems pointless for a 6ft 6in man with a plume of bandaged dreadlocks to spend the evening on a soapbox.

Instead, pin down a consummate live hip hop performance for an ecstatic audience. Once Franti has got the irritating polemic of Chocolate Supa Highway out of his system, later songs like "Food for the Masses" and "Of Course You Can" set an impressive pace. Franti's powerful rapping, the irrepressible presence of Trinna Simmons, his diminutive co-vocalist, a dextrous backing group: all compensate for occasional lyrical ponderousness - "Would you like to look at Madonna's book on sex?/ Or would you rather Alex Haley's book on Malcolm X?".

Taking the cue from his mischievous fellow rappers - who at one point haul someone out of the audience to shake his booty with Simmons - Franti's "I'll Be There (With a Joint)" gives the Forum a fine impression of Rosie Boycott covering Mariah Carey.

As left their last UK performance before recording their next album, you hoped that the Big Funky Giant Franti had learnt a lesson - cruising on the "chocolate supa highway" with an open mind means getting your feet in gear first.