I was watching motorcycle racing at the weekend and noticed that the bikes were taking corners while tilting at well over 45 degrees from the vertical, in fact probably by as much as 60 degrees. Most of the time the bikes managed this without sliding and crashing. How do the bikes lean so steeply and corner on what looks like the side of their tyres without sliding?
鈥� Turning a corner, a motorcycle is forced outwards by centrifugal force as well as downwards by the force of gravity. If the turn is taken with bike and rider too upright, centrifugal force flips the bike outwards and throws the rider off. If the bike leans too much, gravity makes it lie down and the tyres lose grip. It then slides out, with the rider usually sliding along behind.
With the bike leaning over at the best cornering angle, the combined forces push the mass of the bike out and down through the contact patches where the tyres touch the track.
Advertisement
鈥淟eaning pushes the mass of the bike out and down through the patches where the tyres touch the track鈥�
Car tyres only need to work while upright. They have a square cross-section and there is tread only on the crown, not the sides. However, a motorcycle tyre has a rounded cross-section and the tread extends onto the sides of the tyre. This allows the tyres to continue to grip the track, even when the bike leans over in a corner.
Richard Whybray, Omagh, Tyrone, UK