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A look at the Phillip Island circuit

A look at the Phillip Island circuit

A look at the Phillip Island circuit

The average lap speed at Phillip Island is 177.785 km/h, making it the second fastest track in the World Championship calendar behind Assen. This high speed might seem strange at a circuit with very few straights, however, although the main straight is relatively short at less than 900 metres in length, the corner leading onto it and the corner at the end of it are both extremely fast corners taken at more than 180 km/h.

The ideal settings would give the bike stability to be able to take the fast corners with as much precision as possible and use the maximum amount of track surface. There are six corners taken at over 180 Km/h and three of these are negotiated at more than 200 Km/h. Given the presence of these high speed corners, and the constant changes of direction at high speed, technicians tend to fit hard springs so that when the rear of the bike is under compression - thus riding precision is not affected and the rider can maintain the racing line through corners.

However, the presence of many bumps on the track surface means that the springs used can not be as hard as the riders would like. To demonstrate the pressure on the springs, the point of greatest compression on the rear of the bike takes place between corners seven and eight where the bike is travelling at more than 230Km/h. This speed creates a force of more than 500kg on the rear springs.

With regards to front suspension, the points in the circuit where there is most movement of the front shocks are the two hairpins taken at slow speeds. The rider must brake hard at these two points, but this is not a circuit where hard front springs are fitted because of hard braking. Due to the bumpy track surface in the fast corners, softer springs are fitted in the front to maintain precision and grip, despite these bumpy areas. Some of these bumps are so big that the bikes literally take off as they lose contact with the track in both the front and rear. The best place to witness this is at the end of the straight where the bikes leave the ground at more than 305 km/h.

At Phillip Island the gear ratios are a little different since the higher gears are used more frequently than is usual. Most of the corners are taken in third, fourth and even fifth gear. These gears must be set so that there is not too large a step between them and also so that sixth can accommodate speeds of nearly 350 km/h. It is not always easy to find a good compromise. Unlike most other tracks in the MotoGP calendar there are only two corners taken in first and two taken in second.

Another special factor at Phillip Island is rear-tyre wear. As well as being a very abrasive track, the characteristics of the layout of the track put an excessive amount of stress on the rear tyre. The left side of the tyres is critical since the left-handed corner on to the straight is very fast and the rider can open the throttle early. However, in doing so he heats the left side of the tyre to temperatures that can affect the tyre's durability. Sometimes it is necessary to sacrifice rear suspension settings and make them softer to prolong the life of the rear tyre so that it lasts the race distance of 120 km.

Another important aspect at this circuit is the front brake. There are no hard braking areas around the track so brake discs with smaller diameters are fitted so that they reach the correct working temperatures more easily. At Phillip Island discs of 305mm diameter are fitted compared to a normal diameter of 320mm.

Tags:
MotoGP, 2005, POLINI AUSTRALIAN GRAND PRIX

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