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Courtesy Race Access (No further reproduction or commercial usage)
500 GP SECRETS
Second in a series of stories from the Marlboro Yamaha Team examining the intricacies of the world's fastest race bikes
CORNERING
Racetracks are made up of straights and corners - and it's the corners that offer riders the greatest challenge and the biggest thrill, as Marlboro Yamaha riders Max Biaggi, Carlos Checa reveal
This is what motorcycle racing is all about... rocking into a turn at apparently impossible speed, flicking the bike onto its side, kissing tarmac with knee, then cracking open the throttle and launching onto the next straight like a bullet from a gun.
Bike racing is all about speed and, while corners aren't the fastest part of a racetrack, they are the reason the track is there in the first place. Ask any racer - they do what they do because they enjoy scything through corners, not blasting along in a straight line.
"For me, going into a corner is the nicest part of riding bikes - you feel like you're flying," says Marlboro Yamaha Team star Max Biaggi. "You go from upright to maximum lean so fast, it gives me a fantastic feeling."
Biaggi's Marlboro Yamaha Team-mate Carlos Checa also gets his biggest racing thrill from launching through corners. "When the feeling is right, it's a lot of fun," he says. "When you can play with the bike, and it goes where you point it, that's when it's really enjoyable, then you get the confidence to push even harder and win."
And, of course, cornering isn't just big fun, it's where riders and their teams make the difference between victory and defeat, as Yamaha Grand Prix manager Masahiko Nakajima says: "Cornering is most important aspect of performance in racing."
Despite the joy that Biaggi and Checa feel as they hurtle artfully through corners, their art conforms to strict laws of physics, so bike set-up is as crucial as rider input. Through every turn the rider must balance the forces of gravity and centrifugal force, the former makes the motorcycle fall into the corner, while the latter throws rider and machine away from the centre of the corner. The collision of these two forces generates friction between the tyres and the tarmac, the friction providing grip. First of all, however, the rider must get the bike steered into the curve, which he does by applying a negligible amount of opposite lock. That's correct, to go right, he tweaks the handlebars to the left, and vice versa. At the same time he weights the inside footrest to help pull the bike down, while also shifting his body weight to help throw the bike onto its side. All in all, it's a mighty high-speed dance.
Corner entry is vital, not only for a smooth initiation, but also for a good mid-corner and corner-exit speed. Get the entry wrong, and you pay all the way through, as Biaggi's crew chief Fiorenzo Fanali explains.
"You can divide each corner into three parts: entry, apex and exit," says the Italian. "You need a good set-up for the entry, so the rider feels confident to go in fast, so he can carry a lot of corner speed, which will also help him on the exit. You may have the bike well set up for the exit, but if the rider can't go in with speed, that's also going to spoil his exit from the corner. So you have to be careful when discussing things with your rider. Sometimes Max tells me the bike doesn't turn through the corner, but I can check on the data and see that he's struggling to get into the corner, so his apex speed is down, and that's why it's not good on the exit. Sometimes you can change the set-up to improve his corner entry and it will help the rider on the exit. Like everything else in racing, it's a compromise."
Fanali and his fellow engineers have their task complicated by the fact that bike racing is more of a human sport than a technical sport. In car racing you can sit any good driver in the best car and he'd run up front, or thereabouts. In bike racing it's the rider who does the winning. Of course, modern-day GP racing is very scientific, but the more scientific it becomes, the more the scientists (the pit-lane engineers) realise they can't apply hard and fast scientific rules to the process of perfecting machine set-up. Bikes are just too unstable, too human.
As Suzuki GP engineer Warren Willing says: "Dynamically a bike is more like a fighter plane than a car." In fact, some might argue 500s are more complex, because a fighter plane moves freely through the atmosphere while a motorcycle must track the tarmac.
The science of bike racing is most deeply muddied by the human element. There are few scientific consistencies because the rider forms a major part of the machine, over one third of a 500's race-ready mass, unlike a car. Not only that, a rider's style has a drastic affect on machine dynamics, grip and overall behaviour. He can change the way the machine works by sitting in a different position, adjusting his throttle style, hanging off further and so on.
"Max and Carlos are quite different in the way they ride," adds Yamaha GP chief Nakajima. "Max is very gentle and progressive with his braking, and his corner speed is very high, so our first priority with his machine set-up is cornering performance, then braking stability. Carlos is very aggressive on the brakes, so we have to adjust steering geometry and front suspension to suit, then we worry about cornering performance. It's quite difficult to make such different set-ups for both riders."
Of course, there are also similarities in the way in which Biaggi and Carlos ride. Like all their rivals they both hang off their machines to improve cornering performance.
"You lean your body to the inside of the corner to make the bike turn better," adds Biaggi. "But you also feel better when you are off the bike: you can touch the ground with your knee, which helps tell you how far you're over, and you're also in a better position to brake and open the throttle."
Biaggi & Co have another, more dramatic, use for their knee-down style. "If you feel the front tyre slide, you push your knee into the tarmac to pick the bike up and save the slide," Biaggi continues. "But it's a last-chance thing before you crash and it doesn't always work because the bike weighs 130kg and once it's sliding, it's difficult to get back."
Checa adjusts his physical input according to the speed of each corner. "The amount of steering effort you need depends on the track and also the character of the bike," he says. "Going into fast turns you must be really sensitive, especially with the front end. You're going in really fast and it's more of a mental thing than a physical thing. Through slower turns, you need to be more aggressive, more physical."
And it's not only the rider who must adjust his input according to the corner. His technicians must do the same. Ohlins technician Lars Isaksson, who helps with the team's suspension set-up, believes that race engineering is all about compromise and balance. Not only must the rider and his team compromise to get the right performance all the way through one corner, they must also compromise to get the bike working well through different corners on the same track.
"You have to find good balance because we have to set up the bike for the whole track," he says. "We can check everything on the data and if we can see one of the guys is struggling in one corner, we work on that and maybe sacrifice a little bit of speed in another corner, but you get a better overall lap time."
Checa's crew chief Mike Webb also realises that compromise is essential in getting a bike to work in the variety of different situations encountered at each racetrack.
"If you're talking about getting around just one corner, machine stability is the most important thing," he affirms. "But the problem is that racetracks have more than one corner and often they're close to one another, like esses and so on. The rider needs the bike to turn super fast for direction changes, so then you have to start doing things that make the bike unstable, making it steer lighter. Again, it's a compromise."
Going through esses and chicanes requires huge physical input from the rider, who must heave the bike from max lean one way to max lean the other in a fraction of a second. To achieve that he once again uses a combination of inputs: steering, body movement and weighting of the footpegs.
Once into any turn, it is grip that determines how fast a rider can go through that corner, and there is only so much grip available from the front and rear tyres. Today's GP machines can be adjusted to balance that grip, giving more to the front, usually at the expense of the rear, and vice versa, depending on the circumstances. But there's no doubt which tyre is the most crucial to overall rider feeling.
"The most important thing for a rider is good front grip because that gives him confidence," adds Isaksson. "With plenty of front grip he's more confident, so he can be more aggressive. Rear grip is less important because rear slides are easier to control, and anyway, some riders like to slide the bike. Then again, there are other riders who like to have the bike like it's on rails."
That, of course, is the whole beauty of bike racing: every rider has his own way of charging through a corner at lap record-busting speed. And that's just one reason 500 GP racing is the world's most entertaining motorsport.
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