A masterpiece of bubblegum fluff which made its insidious way into every teenaged head that heard it, Bill Martin and Phil Coulter's "Shang-A-Lang" is the Bay City Rollers' masterpiece. They may have made more successful records, and they certainly made better ones. But in regard to laying out the terms and conditions of what would soon become known as Rollermania, "Shang-A-Lang" is peerless. It soared to number two in the U.K. in April 1974 and single-handedly confirmed the Rollers' grip on the hearts of teenybop Britain. Cassidy, the Osmonds, both were pushed aside by the giant tartan juggernaut and, even today, it's hard to hear the song without remembering precisely how menacing that juggernaut looked. The world was drowning beneath a sea of plaid and what were its dying words? "We sang shang-a-lang as we ran with the gang, going doo-wop shee-doobee-doo-ay." They really don't write them like that anymore.