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/707505
VOL. 53 ISSUE 29 JULY 26, 2016 P81 THAT GORGEOUS CHASSIS "T he T12 chassis has the hybrid design which my father typically favored, with the engine used as a fully stressed structural component. The cast magnesium steering head is attached to a very stiff space-frame made from military-level steel tubing, which al- lows us to cut down on wall thickness and thus reduce weight without sacrificing stiffness. This in turn is attached via special bolts to the twin rear side plates which are also cast in magnesium, and in which the single- sided swingarm likewise cast in magnesium pivots, while the Marchesini wheels are both forged magnesium to my father's design. There are Ergal 55 aluminum mounting plates milled from solid at- tached to the sides of the cylinder head to carry the bodywork, while all the footrests and linkages are also billet aluminum. "Naturally, the chassis is fully adjustable in terms of steering geometry and suspension settings, as well as having a variable height swingarm pivot. The choice of the various materials comprising the chassis has a technical objective, because of the resonant vibration, which can amplify itself dynamically to the point that it upsets the overall handling and suspension compliance, and can especially create chatter. Using a variety of materi- als, which have different points of resonance, enhances the compli- ance of the suspension at extreme angles of lean. So making a part in mag- nesium has one degree of resonance, making it in aluminum another, and in carbon fiber a third. My father designed the T12 to be able to control the chassis resonance in such a way that it en- hances the motorcycle's behavior. This is why he developed the modular frame design concept, to be able to do this." "He also developed— and patented—a means of altering the transverse rigidity of the chassis. He did this with a system, which subtly allows you to vary to a micrometric extent the stiffness of the chassis. This is important once you adopt more than around 45 degrees of lean angle in a turn, because the suspen- sion is no longer able to work truly effectively, and forces are translated back into the frame. If you're able to finely adjust the transverse flexibility of the frame to an appropriate degree, you can then adjust the suspension to better respond to these demands, as well as to optimize the performance and durability of your rear tire. Our patented system permits that. "The same consider- ations apply to the single- sided cast magnesium swingarm, which was my father's chosen design ever since the Ducati 916 almost 25 years ago. Why? There are three reasons and the first two are the least important: it looks nice, and you can change the rear tire quickly. But the third reason he always chose this is the most impor- tant. With the constant improvement of rear tire performance week by week—not year by year—it remains vital that you should achieve perfect torsional stiffness for the swingarm, but it's increas- ingly desirable to have some transverse flexibility which results in a degree of controlled deflection of the rear contact patch, which you cannot obtain with a dual-sided swing- arm." (Top) The cast magnesium steering head is attached to a very stiff space- frame made from military-level steel tubing, which allows us to cut down on wall thickness, and thus reduce weight without sacrificing stiffness. (Bottom) In typical Tamburini style, a single-sided swingarm is used.