1991 Specialized S Works :

The S Works bikes were the "skunk woks" bikes from Specialized.  They were pushing the envelope to make them the best they could with very little regard to price.  As the S works bikes got better each year, the previous S works designs often got passed down to the regular production bikes.  This is getting towards the end of the production for the steel bikes.  This one uses a Suntour XC Pro drive train with a bunch of Specialized designed parts (pedals, cranks, rims, bar/stem, post..).  This one also features the Suntour BEAST front shifting system.  One quarter of the chainrings are hinged which allows the chain to move up and down the rings when the signal is sent by the shifter.  It is somewhat similar to a rail road switch in that it moves the hinged portion of the chain rings up or down to perform the shift.  Not the easiest thing to describe but it makes sense once you see it in operation.

Bar with "Shifter'	Control box and changing mechanism	Front side of the hinged chainrings