Cornering is a thrilling yet complex aspect of motorcycle riding. It involves several forces and factors, including the interaction between tyres and the road surface.

For me, one of the most intriguing aspects has been understanding that optimum drive occurs when the rear tyre spins 5 to 15 percent faster than the front tyre. Yep, you read that right.

Let’s break it down and see if we can understand this better.

Weight Transfers in Corners

When a motorcycle enters a corner, weight shifts. We already know that weight transfer is a dynamic process and moves forward as the bike slows and towards the rear as it accelerates.

During cornering there is also sideways weight shifting from the inside to the outside.

As the bike leans into a corner, this results in a transfer of weight to the inside of the turn during the initial part of the corner.

However, as acceleration forces come into play, especially when exiting the corner, weight shifts toward the outside of the tyre. This dynamic weight transfer affects tyre behaviour.

The Role of Traction

Traction is crucial for maintaining control in corners. It’s the grip between the tyres and the road that allows the motorcycle to stay on course and not slide out.

There are two types of traction (friction) to consider.

Static Friction – Maximum Grip

Static friction is the traction when the tyre is not slipping. It provides the majority of a tyre’s grip when it’s in contact with the road and not sliding. This is what allows the motorcycle to maintain control during normal riding conditions.

Dynamic Friction – Slip

Dynamic friction comes into play when the tyre starts to slip or skid on the road surface. This occurs when the tyre’s rotational speed doesn’t match the speed of the motorcycle. Dynamic friction results in reduced traction. However, in certain circumstances, it does not result in less acceleration.

For example, anyone who’s ever ridden a dirt bike in earnest knows that optimum drive occurs when the rear wheel is spinning and the back end of the motorcycle has ‘slipped’ to the outside.

Rear Wheel Spin on a Motorcycle

So why is it that when the rear tyre spins slightly faster than the front tyre it can be beneficial?

Negative Slip Angle:

In a corner, the motorcycle’s tyres experience what’s called a ‘slip angle’. This is the angle between the tyre’s orientation (the direction it’s pointing) and its actual path (the direction it’s moving).

That’s right, the actual path taken by the tyre is not the same as the direction the tyre is pointed.

That slip angle is either negative or positive, depending on tyre orientation and direction it is travelling.

In a left hand corner and turn, if the front tyre was pointed a bit to the right of the direction the motorcycle is actually traveling, we would have a positive slip angle.

Conversely, if the tyre was pointed a bit to the left of the motorcycle’s direction, [refer to the images] we have a negative slip angle. This difference between the tyre’s orientation and the direction of travel is referred to as the slip angle.

Slip angle, also referred to as the “cornering angle” or “yaw angle,” is important because it affects the forces acting on the tyre. Tyres experience forces in two directions.

1. Longitudinal Forces: These forces act in the forward and backward direction and are associated with acceleration and deceleration.

When a rider accelerates, the rear tyre generates longitudinal forces to propel the motorcycle forward. During braking, these forces act in the opposite direction to slow down the motorcycle.

2. Lateral Forces: Lateral forces act sideways and are primarily generated as a result of the slip angle.

When a motorcycle leans into a turn, the tyres need to produce lateral forces to counteract the centripetal force and keep the motorcycle on its curved path. These lateral forces are what enable the motorcycle to turn effectively through the corner.

There’s one thing we have not yet mentioned.

Tyre Behaviour at Lean and Its Effect on Slip Angle:

The part of the motorcycle tyre that is in contact with the road during a turn is on the inside of the tyre, not the centre, and this can affect the slip angle.

This effect is primarily due to the shape of the tyre and how it interacts with the road surface.


During a turn on a motorcycle, the tyre leans over on an angle with the motorcycle. At this angle the portion of the tyre in contact with the road is not along the centre line of the tyre. It is actually on an area of the tyre closer to the inside of the curve.

If we were to draw an imaginary centre line representing an axis through the axle of the wheel while it is on this angle, that axis would point to the ground on the inside of the curve. This results in the wheel experiencing a conical shape effect.

The tyre wants to roll in a similar way to an imaginary cone rolling on its side around that centre point. This is known as the ‘Rolling Cone Effect’.


Suppose the tyre was rolled while on this angle at a slow speed. It would naturally want to roll in a circle like a cone around a centre point determined by where the axis points to the ground on the inside of the turn.

But as speed is increased the arc of that circle is impossibly tight so the actual line the tyre follows is wider which creates a slip angle. In reality the tyre is not actually headed in the direction it is pointed.

It is pointing in towards a tighter arc, but physically travelling on a wider arc or line.

It’s this difference between where the tyre is pointed and where it is actually travelling that creates the ‘slip angle’.

The conical shape changes with lean angle, as does the location of the contact patch. And these factors contribute alongside other factors such as speed, to variations in slip angle.

Traction Control Settings:

Modern motorcycles are equipped with traction control systems. These systems allow riders to adjust how much slip is permitted.

Settings usually range from 0 percent (no slip allowed) to around 5 percent to 15 percent (some slip permitted).

The Balancing Act:

An extreme example of this whole concept of slip and traction is a speedway bike. In a turn the bike performs best when it is cranked over on an angle and the rider causes the rear wheel to spin and drift very wide. A large negative slip angle is created which generates a ‘negative slip force’. This in turn reduces the corner force demand so that it can be matched by available friction.

Allowing a small amount of controlled slip at the rear wheel of a road bike on an asphalt track helps optimise traction and stability during aggressive cornering. This controlled slip occurs within the static friction range, which maintains grip. It prevents the tyre from transitioning into dynamic friction, where traction is reduced.


In motorcycle cornering, optimising drive occurs when the rear tyre spins slightly faster than the front tyre, typically within the 5 to 15 percent range. This controlled slip within the static friction range allows the motorcycle to maintain grip, stability, and control during aggressive cornering, striking a balance between power and traction.

Interesting? I thought so.

Remember to check out our YouTube channel covering all things motorcycling – The Bike Stig YouTube Channel


1. A multitude of sources that discuss the technical aspects of – Motorcycle Traction Control Systems

2. Motorcycle Tyre Technology (Source: Michelin)

3. Motorcycle Engineering (Source: Andrew Livesey)

4. Motorcycle Dynamics (Source: Vittore Cossalter)

5. Corner Force: What It Is and How It Is Generated (Source: George A Cairns B.Sc.)

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