Cycle News - Archive Issues - 2000's

~seal section The appliance of science in the bodywork goes all the way to actually weighing Biaggi for the carbon-composite seat, which effectively acts a subframe on the YZR. His height and position on the bike are also logged for computer simulations on any new designs. Crust continued: "The seat is strengthened underneath because we don't use a subframe. The unit is its the bike gets flipped on its side, that's when he gets the movement and gets a feel for the rear tire. If it's too stiff there's no feeling for him and he'l; crash. If there's too much flex, the whole bike will get out of control. We can't move the engine around inside the chassis, but you can move everything around the engine. The oldfashioned way of moving the engine means you also have to move airboxes and exhausts, which is when it gets complicated." own subframe, and that's one of the technique known as 'trail-braking'. He wants to know exactly how much Trip-Ie Clamps feel he's getting from the lever when he's braking. It's nothing scientific, just how he likes it." The upside-down fork is bolted to the steering head in a massive three-way variable triple clamp. Steering head ~Wheels column inserts are probably one of the most adjustable features on the bike. Biaggi can move it front to back by 8mm and he can change the angle Crust described the lightweight carbon front Marchesini wheel as "astro- from zero to two degrees. Crust nomically expensive", but adds the added: "It all depends on whether he benefits make it worthwhile. The wants the bike to turn quicker or wheels cost about 10 times more than the magnesium version they use respond better to direction changes. hardest things for us to get right We just change the triple clamp to because you need to hang exhausts from it. It's also where the onboard get the trail and angles right without camera equipment goes. You have to take that into account in the design process because you are constantly adding weight to it on top of the rider's body." The swingarm takes a month to design so that it offers Biaggi maximum feedback. His bike has quite a long swingarm this year for better stability, and also to provide the grip levels he desires. Among its most important features are stress gauges G)Frame Biaggi's aluminum twin-spar chassis may look simple enough, but two designers have spent at least two months developing it in Japan. The chassis features a total of 50 different parts that take two weeks to machine and another two to three days to weld together. Chassis design is a very complex procedure. Once the dimensions are finalized and the stiffness of the finished article has been determined, designers have to consider where to place the engine for good weight distribution - and where to fit the electrics, airbox, exhausts, radiators, etc. Biaggi's current frame is one that Yamaha has been refining for a number of years, developing the wall thickness so that the chassis bends vertically and horizontally. Biaggi's chassis will last him a season, barring any major crashes. That's because 500cc four-cylinder bikes have a minimum wet weight limit of 288 pounds. In the past, when there was no minimum weight limit, engineers used to gain most of the weight saving by making the frame walls as thin as possible. Trouble then was the lightweight material was prone to fatigue and often cracked. Racing frames need to be stiff - but only to a point. A certain amount of flex is needed to aid feedback to the rider. At the start of the season, Biaggi was still using three different chassis before evaluating which one was the best. The chassis also offers multiadjustments for steering geometry, wheelbase and ride height. "The twist in the chassis is where Max will get feel," Crust said. "When on the chassis and swingarm so the crew knows how the bike is handling. "We can adjust the swingarm ride height within an 8mm parameter, which alters the chain force and any amount of suspension squat," Crust said. "Max also has five different variable rear-shock linkages which determine the rate of suspension movement." ~Fork One of the most crucial aspects of Biaggi's bike are the $14,000 Ohlins forks. Such is the importance of fork set-up in GPs now that Biaggi has his own technician to work exclusively with him. To speed up the process of finding a good set-up, Ohlins now has a suspension dyno at every GP. Biaggi can choose a variation he thinks may work, and it can be tested in the truck without him even needing to go out on the track. "We are working on the front suspension all the time, not just in terms of damping and spring rates, but with the stiffness of the inner and outer fork tubes," Crust said. "This is a critical point, because it's where Max will feel the front under hard braking when he pitches into a corner. We obviously have the ability to adjust rebound and compression damping, but we can change everything inside to alter the damping, too. When you've got four hours to set up a bike for a race, that's the area you concentrate on." on the rear. The team carries more than 100 wheels for the two riders. even altering the rear ride height." "We use a carbon front to reduce unsprung weight on the front end ~RearSho

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