GT's 1996 proof of concept IT gearbox downhiller (missing its front fender) was made by Aaron Bethlenfalvy - GT's head of design. Jim Busby designed the suspension and gearbox drivetrain, which used a Shimano Nexus 7-speed planetary hub transmission.
The Nexus gearbox was in the downtube. Idler pulleys were necessary to make the chain-drive behave at speed.
Hope disc brake? Yep, they've been in the game for a while. The drivetrain was reversed left-to-right, to accommodate the secondary drive sprocket that was bolted to the left hub flange of the planetary gearbox.
GT's 2006 IT-1 was the production version of GT's gearbox descender, which was much more refined, but not as futuristic looking.
The Shimano Nexus 7-speed hub looks like it was actually designed to be a frame-mount transmission, and the chain drive has been updated with a roller guide, which was state-of-the-art DH hardware at the time. GT's high-pivot swingarm and no-growth chain-line is cutting edge today,
Not exactly period-correct, but the IT-1 looks contemporary enough to pull it off.
The 2003 i-Drive Marathon was one of the many iterations of the dual-suspension platform that elevated GT to the forefront of the trailbike game. Its gusseted aluminum frame and interrupted seat tube mast were hallmarks of the era.
GT introduced molded carbon frame technology using thermoplastic resin. The 1998 STS DH Lobo showcases the construction, which required aluminum inserts where stresses were concentrated. That limitation boosted the Lobo's weight and ultimately spelled doom for GT's thermoplastic carbon program.
The 1996 LTS-1 was the most innovative suspension designs of the early development period. Its scissor linkage compressed the tiny shock with a favorable leverage rate, which extended the wheel travel to somewhere around 55 millimeters. Its location behind the seat tube allowed GT to offer a very conventional looking chassis to reluctant dual-suspension converts.
The 1992 RTS was GT's first and perhaps, its most famous dual-suspension bike. This model has been updated with an aluminum swingarm (the original steel one cracked and its owner still races and rides this bike). The pull-actuated-shock design was travel-limited by derailleur technology, as its high-pivot swingarm created monstrous chain growth. Inventor Jim Busby was well aware that the high-pivot's upward and rearward axle path would optimize the suspension's performance, which later inspired him to solve the chain growth issue and ultimately design GT's i-Drive system.