Valentino Rossi analyses both technologies

4-Stroke Bikes. The Big Revolution
T4-Stroke bikes have meant a real technological revolution in the World Championship. More powerful and more sophisticated; they are a great show for the fans. But their special technical features force riders to ride in a different way. Their reactions are different, the settings as well, and the riding style has some aspects the riders have to consider from a different point of view. Valentino Rossi, who has won races on 2- and 4-strokes analyses the differences between both technologies.Riding style ‘With the new Repsol Honda RC211V everything is gentler and slower, its response is far more docile and gentle and so it is generally a question of riding gently and not aggressively. At the same time, this allows you to ride more comfortably. With the two strokes you always seem to be on edge, risking the unthinkable, but with the new bike you know what is going to happen because everything is more foreseeable.’The line in the corners ‘For several reasons the 500 are faster than the four strokes when they go through the corners. On going into the corner after the braking there is hardly any difference, you only slightly notice the extra weight of the RC211V, but there are great differences in the next two steps. With the four stroke, the passage through the corner and the exit are soft actions that even seem slow, but with the 500 you have to exaggerate things, straighten the bike aggressively and accelerate as soon as possible to get out as soon as you can using less power than with the new bike. In fast corners I don’t think there are any differences, the two bikes go through the corner as fast as each other.’Braking ‘The RC211V has a dry weight of 15 Kg. more than the NSR, and this is very noticeable at these levels of competition. The new bike goes faster in the straights, but when you brake you have to start a lot earlier, some fifteen metres earlier, because you get there faster and with more weight. Another added problem is the engine brake, because with the 2 strokes the back wheel behaves neutrally in braking, whereas with the 4 strokes the back wheel always turns slower than it should and this causes movements in the whole of the back carriage and the typical fanning.’Acceleration ‘With the 4 strokes, aceleration has become far simpler. With the 500, when you turn the trottle a quarter it does not mean a quarter more power, but rather the power increases as though it was a turbo. However, with the four strokes there is a greater relation and better balance between the accelerator and the power transmitted to the back wheel, and with the four strokes it is very easy to make the back wheel skid and this makes the Repsol Honda RC211V a very amusing bike to ride.’Stability ‘As I said, the RC211V is 15 kg. heavier, and this is very noticeable when you talk about competing and any detail makes a difference. The 500 are bikes conceived only for competing, whereas the new Honda is a bike that is similar in many ways to a Superbike, that is a road bike improved for racing. The RC211V is much ‘softer’ and ‘more honest’ than the 500, because with the 2 stroke, errors can be very costly. Both are very stable bikes both in the fast sections and in slow corners, braking and changing direction, but here, with less weight, the 500 are better.’Set-up ‘The 500 need a much more precise set-up, and we could say the four strokes are a little more permissive. But the problem we are having this season is that there are circuits where we have never ridden with the new bike, and this means we have to start from scratch with the set-up and haven’t got any reference. And we have to find the right adjustment in little more than four hours to get ready for the race.’Top speed ‘The four strokes are faster bikes in the straights than the two strokes, mainly because they have more power and give it more gently. This can be seen from the races we have had up to now, in the straight the four strokes generally go past the 500 without much trouble.’Tyres ‘With the four strokes, as I said before, there is a close relationship between the accelerator and the back wheel, so when we accelerate a little we are already giving power to the rear rubber. With the new bike you can accelerate when you are leaning tightly, which wasn’t the case with the 500, where you had to raise the bike to be able to open the throttle. This and the increased weight have meant we have had to work hard this winter with the guys from Michelin, but we finally achieved a very good product, such a good product that they can also be used and are giving better results for the 500 this season.’