Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/127558
GRIDING IMPRESSION 1993YamahaGTS1000A e By Kit Palmer t last, a motorcycle truly worth getting excited about. . • It seems like it's been eons since the last major technological breakthrough was availabfe on mass-produced motorcycles. Sure, we've been teased by numerous bizarre concepts and strangelooking bikes at major motorcycle shows all over the world year after year, but seeing one of these fu turistic bikes on the showroom floor has been a'difIerent story. Well, leave it to Yamaha, one of the first OEMs to offer a single-shock rear suspension system on production motorcycles in the late 1970s, to finally get the ball rolling, once again. Yamaha accomplished this with the introduction of the GTS1000A, an "Advanced Sport Touring" street bike that features a grab bag full of hightech goodies, such as a fourcylinder, 20-valve, 1003cc, water-cooled, and electronic fuel-injected (EFI) motor, an anti-lock braking system (ABS), opposed six-piston front brake caliper, a catalyst exhaust system, and most notably, an all-new Yamaha-dubbed "Omega" chassis and single-sided swingarm front suspension: Obviously, the chassis and front suspension system are the "biggies." The GTS1000A is the first mass-produced motorcycle to use a single-sided swingarm front end design. The first motorcycle produced with a similar design, a hub-center steered motorcycle, was the Italian-made and performanceminded Bimota Tesi, which was introduced in 1991 in limited numbers and A 16 had a $40,000 price tag, as compared to the $12,999 asking price of the GTS. It almost goes without saying, that the GTS is the most expensive production motorcycle Yamaha has ever built, topping the previous price tag leader, the Venture Royale, by some $1500. Yamaha can't take all the credit for the unique front-end suspension design of the GTS. The Japanese manufacturer licensed the patent rights to the suspen- steel-tube subframe attached to the aluminum main frame. Ball-joints located at the front of the swingarm just above and behind the axle, and just below the steering box, permit the front wheel and vertical spar assembly to turn left and right. Okay, so what are the advantages of the single-side swingarm front suspension over the traditional telescopic fork design? sion technology from RADD, Inc. James Parker, president of New Mexico-based Rationally Advanced Design Developments, invented the system in 1982 and obtained the patent in 1985. Yamaha based its front end design on RADD's technology. So, how does it work? According to Yamaha, the rider's steering input is transmitted from the handlebar crown through a steering box to a vertical cast aluminum spar which turns the front wheel. This vertical aluminum spar is also supported by an upper arm mounted between the top of the spar and the main frame. The steering head assembly is supported by' a Again, according to Yamaha, there are many. Perhaps the most immediately realized benefit is the anti-dive characteristics of the new front suspension. The system is designed to reduce frontend diving both under normal braking and while cornering. Other related ad vantages include exceptional front/ rear wheel weight balance, lower center of gravity, increased rigidity and independent steering and suspension functions. The single-sided swingarm front suspension also allows for a completely unconventional frame. Simply put, because of the new front suspension, there is no longer the need for a "back- bone" section, steering stem or front downtube/s. Instead, the main frame is made up of beams constructed of multiple aluminum castings welded together that closely surrounds the engine. ~n effect, the engine is the frame. Yamaha claims this design increases overaLl rigidity of the motorcycle immensely. Traditional frames carry suspension and steering forces up along the fork, Over the engine and finally to the re~r swingarm. The GTS's frame is vastly different because it distributes braking lind suspension forces in more of a straight line - from the front swingarm through the engine to the rear swingarm. Plus, added str~gth is achieved by the frQnt swingarm pivots being widely spaced to spread side and tor~ sional loads over a wider area than traditional front suspension designs. Because the new frame allows the front suspension to be independent of the structure which steers the front wheel, Yamaha had less reshictions in placing critical components. This means Yamapa engineers had the freedom to design and place essentials like the' gas tank, seat, handlebars, fairing, instrument panel and steering head around the rider for a more comfortable riding position. The single front coil spring/oil damper shock, that mounts between the swingarm and frame, is-f~y adjustable. Front suspension travel is 4.57. inches. In the back, the GTS features a "traditional" single-shock linkage design, with a heavy-duty aluminum "delta box" swingarm. The rear suspension offers 5.12 inches of wheel travel. Yamaha engineers certainly didn't ignore the GTS's front and rear braking