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GP Week : Issue 82
Moto GP FEATURE >> "What works best in racing," a wise old guru once told me, "is what worked last year, plus a couple of percent." He was Kel Carruthers, and that was way back when, at the time when the former 350 World Champion (the last on a four-stroke) was approaching the end of a career of shepherding Kenny Roberts and then Eddie Lawson to serial World Championships. Times have changed, but the dictum hasn't. Exactly the same is true in today's MotoGP. It's proved by the homogenous machines. After the death of Aprilia's hopeful three-cylinder Cube and the sad obsolescence of Honda's sonorous V5, the grid is full of sundry V4s and Yamaha's virtual V4. All rely on evolution rather than revolution. The same slavish reliance on similarity applies to the chassis. The signal exception to the fabricated beam-frame is Ducati's carbon-fibre frame. This aside, convention rules. Most especially when it comes to suspension. The MotoGP bikes not only use the same type -- telescopic fork up front and swing-arm (trailing link) at the rear, the latter operating some sort of linkage that gives a rising rate to the compression of the spring. The all even use the same make: Öhlins. Not all race engineers necessarily subscribe to conservatism, but there isn't really all that much room to move in terms of engine design (and even less, when restricted-bore 1000cc bikes come in a couple of years). Bodywork is also very strictly proscribed, ever since the sad demise of the old dustbin fairings of yore. The chassis does allow more possibilities. And with Moto2 having emerged as a playground for chassis designers, can we expect some heretics to shake the tree? There are certainly sufficient numbers: 15 different chassis constructors have wrought frames to carry the one-size-fits-all 600cc Honda engine, and at first sight there seems to be a fair bit of variety, with a couple of tubular steel designs to upset the usual recipe of fabricated aluminium beams, the design favoured in one form or another by all in MotoGP except Ducati. In fact numbers make a difference: 11 of the 40- plus bikes are by Suter Racing Technologies, with very conventional beam frames; while the most interesting of the tube-chassis bikes is the MZ, of which there is only one example. These numbers are set to change, with two space- frame bikes disappearing. The RSV chassis was chosen for the pair of Mapfre Aspar bikes of Julian Simon and Mike di Meglio, although only after original chassis suppliers Aprilia had pulled the plug on the contract. Now, as per GPWEEK reported last week, the top- level Spanish team is to ditch the RSV frames and move instead to the class favourite Suter. The tubular chassis was both heavier and bulkier, blamed by the team for a lack of top speed. This need not necessarily be so, however, according to ex250/350 GP winner Martin Wimmer, new owner of the classic MZ brand. Wimmer, hands- on team chief as well as factory proprietor, points out other advantages to this classic yet still inventive way of chassis structure: "If you want to change anything, you can build up a completely new chassis in just a few days." In this way things like stiffness ratios as well as overall geometry can be quickly developed. With this new breed of bike still in its first year of full-on development, this sort of flexibility could be valuable. It was the same route adopted by Ducati, allowing Ducati Corse's urbane chief Claudio Domenicali, when asked if he thought a steel trellis chassis could cut it up against the aluminium beam frames, to give this reporter the elegant reply: "That is like asking the host if the wine is any good." It is no coincidence that it is European factories that embrace this inventiveness and MZ (itself the plucky rebirth of the former East German factory that pioneered the high-performance two-stroke) has more novelty to come: Wimmer plans to intro- duce his own sophisticated front suspension system that replaces forks with a linkage that varies the rake and trail during braking, cornering and acceleration. Moto2 does offer new opportunities, but innovators need faith and courage: doing things differently has not historically paid much in the way of dividends. Front suspension has the richest history of heresy, among designers to whom telescopic forks are an engineering anathema. Experiments range from sundry leading-links to variations on girder forks that use wishbones instead of the flimsy short links of vintage machines. One notable was French former F1 driver and designer Eric Offenstadt, who built an early mono- coque chassis, but is more famous for a strange arched trailing-link front suspension design in the 1970s for the 250/350 class. The Swiss-built Fior used a Honda500 engine with a wishbone-and-girder system up front. One of the most successful designs was by British club racer Norman Hossack, and a similar telescopic-fork/wish- bone system was adopted by BMW for its road bikes. But the most glamorous series of highly adven- turous failures came from France, sponsored and named by Elf. Through the 1980s a series of machines offered leading-link and other varieties of front and rear suspension, in a chassis owing nothing to motor- cycle heritage and everything to science. On paper the strikingly unconventional machines should have been able to achieve higher cornering limits that conventional designs: they should have been able to brake harder and later, and to have put the power down earlier. Perhaps it was the lack of heritage, but the Elves serially failed to do this. The science didn't factory in the human equation, and the bikes lacked the 'feel' so essential to a rider exploring the outer limits. Doesn't mean heresy is wrong. Not necessarily. But it does underline the point: "What works in racing ..." 37