Understanding Motorcycle Tyre Grip
Presented by Pirelli Tyres
A motorcycle tyre is an extraordinary piece of engineering.
These black round sticky things are able to keep our motorcycles in control at extreme speed and lean angles, relying on only two small patches of rubber in contact with the asphalt.
However, most riders underestimate the high level of grip available from their tyre’s.
This misperception of available grip can be a negative for the rider resulting in reduced riding pleasure, but there is also a darker side.
THE DARK SIDE
A big contributor to rider trauma on the road is the survival reaction.
Survival reactions are primarily caused by the rider’s lack of understanding of their limit and the limit of their machine.
More precisely, the rider doesn’t sufficiently understand the grip that is available from their tyres.
This survival reaction will often cause the rider to overreact and panic to a small problem, such as mid corner gravel or an oncoming car cutting the corner, resulting in a bigger problem that could have been avoided if the rider understood the available grip.
For example, a corner tightens unexpectedly. The rider panic’s and grabs the front brake overloading the front tire and slides across the road. A more experienced rider may have rolled off the throttle; trail braked or simply leant the bike over more.
Some may say prevention is better than cure and the rider should have approached the corner slower, however this is the reality of what’s happening on our roads. We will save the road-craft lesson for another day.
Understanding the overall grip that your tires can supply at a given time means you can ride that much closer to the limit on the track, or with a greater safety margin on the road.
Assuming the road surface is free from debris, the main contributor to grip is the weight or load on each tyre.
Try sliding an eraser across your kitchen table. Now try the same thing pushing down hard on the eraser. You will notice the difference in grip with more vertical load.
To apply this understanding to your bike, we can use the dollar analogy.
Imagine your front tyre has a dollar’s worth of grip. You could spend 60 cents on braking which leaves 40 cents for cornering or 10 cents on braking and 90 cents on cornering.
The more spent on one, the less you have to spend on the other, and there’s a big penalty for overspending!
Awareness of bike balance is also an important factor. Weight distribution between front and rear tyres is constantly changing as you corner, accelerate and brake.
Obviously when you brake, the bike pitches forward applying load to the front tyre. When you release the brakes, weight comes off the front tyre and starts transferring to the rear.
The key is to load the tyre progressively to build pressure on the contact patch. This applies to braking, acceleration and cornering.
Your tyre contact patches may be small but the level of pressure at that point is high when the vertical load is high.
Problems arise when a rider overloads the tyre by grabbing the throttle or brake, rather than applying the input smoothly and gradually.