The greatest band that never was is on the road again. Director Rob Reiner's 1984 film This Is Spinal Tap was both the first mockumentary and a spoof so convincing that even the hardest of rockers blinked and believed they had seen this band in concert. Hello, Cleveland! Later appearing in A Mighty Wind as hysterical folkies, Christopher Guest, Michael McKean, and Harry Shearer once more doubled as actors, with Guest hitting a triple as the film's director. Shedding the spandex and the hairpieces, this is the trio's first outing as themselves, playing acoustic guitars on quiet covers of "Big Bottom" and other non-chartbusters. The 30-date tour started in Toronto and hits Oakland tonight.