The laws of physics govern everything, and motorcycles are no exception, which is why a simple understanding of them can make your ride so much more enjoyable. I know physics wasn’t a favourite subject for most, so my goal with this article is not to bore you to death with formulae, but rather to make it as relatable as possible. Well, here goes.
Grip. Yes, traction means grip. But how does it work? For traction to occur, you need two surfaces; in our case, the tyre of the bike, and the road. What is important though is understanding that it depends heavily on two factors: weight and material in contact. Lesson one is extremely simple and straightforward, (unless you want formulae). Weight has a direct relation with grip, so the heavier the bike, the greater the traction. So if all things remain the same, a Triumph Rocket III weighing 350kg will offer more grip than a bike weighing 150kgs on a flat surface. Or a rider weighing 100kg will end up extracting more weight out of the same bike than when loaded with an 80kg rider. Simple enough.
Now the materials in contact have a major effect too, which is why I feel lesson two is extremely important, as it is oft-ignored. A rubber tyre in contact with a tar road will have great traction between it, but the same tyre on gravel, mud or a wet surface will have a highly reduced amount of grip. While most people know this, they tend to forget that traction is a force exerted between TWO surfaces, and not one. Just rub your palms together quickly, and you’ll notice that both of them heat up. Therefore, besides road surface, tyre surface is just as important. While the difference between soft/hard compound tyres will be discussed later, the basic rule to follow is that balding tyres will reduce grip, as deteriorating tyre condition is as bad as loose gravel. So the next time you suddenly come across dirt strewn across the road, remember you don’t have the same level of grip you are accustomed to, and adjust accordingly.
To properly understand this, it is crucial to introduce the concept of Inertia, which is the tendency of a body at rest to stay at rest, and a body in motion to stay in motion, unless acted upon by an external force. A classic example of this is you falling forward when the local train you are travelling in applies the brakes. That’s inertia.
Now, it plays a crucial role in acceleration and deceleration on a motorcycle. Every time you hit the brakes, inertia tends to throw you forward. This you notice. What you may not realise though is that this results in a lot of weight transfer onto the front wheel, which ends up getting a lot of grip, thanks to what we learned above.
So much so, that studies suggest that 70-100% of braking load is taken by the front wheel alone. This is why only using the rear brake results in a much lower efficiency of slowing you down.
How does this affect your riding? Well next time you need to slow down, remember to use more of the front brake and less of the rear. You will slow down much faster, I promise.
Ok, it’s time for lunch, which means this lesson is over! No, I’m kidding, for this weekly series (every Wednesday) is just getting started. Today I went over two topics that will prevent you from falling off. Next we shall explore tyres, banking and aerodynamics (yes, how to go faster). Like this, it will remain super simple, and easy to remember. So forget all you learnt in school, for this is all the physics you need!