BTO, Bachman-Turner Overdrive, rock band including Robin Bachman, Randy Bachman, Blair Thornton and Fred Turner. They were internationally popular during the mid-1970s. BTO's third album Not Fragile, spawned the million-selling single "You Ain't Seen Nuthin' Yet." By 1977, when Robin Bachman left, 20 million records had been sold worldwide. BTO continued touring and recording. Until 1979 it was one of the most successful Canadian rock bands; it reunited in 1984 and toured Canada.