How Can Understanding Physics Help Me Go Faster on My Bike?

Do you or does someone you know ride a bike? Chances are you’ve answered yes. Today, people all around the world use bikes every day for transportation, for exercise, and even just for fun. But this wasn’t always the case. The first bicycle was invented in 1817. Before that, most people believed it would be impossible to balance on top of two thin wheels, one in front of the other.

Did you know?

In the early days of the bike, people had to take special bike-riding classes. This is similar to how you have to take driving lessons before you can get your driver’s license today. 

If you’re taking a leisurely bike ride into town to get an ice cream cone, you might not care how fast you’re going. But what if there was a delicious holiday meal waiting for you at home? I bet you’d want to go fast then!

When you think of going faster on a bicycle, you probably imagine working harder. Would you believe me if I told you that there are ways to increase your speed without using any more effort? Well, there are!

Let’s look at some of the forces that oppose the forward motion of a bicycle. And then, let’s look at some ways that you can decrease the magnitude of these forces so that you can go faster.

How does gravity affect you on your bike? 

Why is it harder to cycle up a hill than on flat ground? Because when you are biking up a hill, gravity is pulling you backwards down the hill. Gravity is the force that prevents us from floating away to outer space. The heavier you are, the greater the force of gravity acting on you. That is because your weight is your mass multiplied by the force of gravity (9.8 Newtons/kg). In other words, you can decrease the force of gravity pulling on you by making you or your bicycle lighter. For example, you can ride a bike with a lower mass. You could also carry a lighter backpack. Or maybe leave your rock collection at home if you are planning to bike up a hill!

Did you know?

Carbon fibre is one of the lightest materials used to make bike frames. A carbon fibre bike can have a weight of less than 6.8 kg (15 lbs.). That’s about the same weight as a small dog like a Toy Spaniel!

How does air resistance affect you on your bike? 

When you are biking, air resistance can seriously slow you down! Air is made up of particles, and you have to push them aside as you move forward. It’s kind of like being a football player and having to push opposing players out of your way as you run across the field.

Air resistance (also known as drag) is most noticeable when you are travelling quickly. You might not notice it when you are walking, but you can probably feel it if you hold your arm out the window of a moving car.

To increase your speed on a bike, make your body smaller, or more aerodynamic, so there are fewer air particles that need to be pushed aside. This is why cyclists in races often hunch down low over top of their handlebars.

How does rolling resistance affect you on your bike? 

Have you ever had to push a heavy object, such as a desk, across the carpet? It’s a lot of work, isn’t it? This is because there are electromagnetic forces attracting the molecules in the desk to the molecules in the ground. If you want to move the desk, you have to first overcome these forces. We call this type of resistance sliding friction. What if you added wheels to the bottom of that desk? Moving it would be easier, of course! That’s because wheels don’t have to overcome sliding friction. But there is a different, smaller force that wheels have to overcome. It’s called rolling resistance.

Want to see how rolling resistance slows you down? Watch the tires of someone else’s bike as they ride. If you look really closely, you will see that the tires partially flatten. When this happens, some of the kinetic energy (the work your legs are doing when they’re pedaling) is lost. This means you will move more slowly.

How can you decrease rolling resistance? Pump your tires with more air! Your bike's tires are filled with air. Higher air pressure makes them firmer - that is, they don't flatten as much, which means there is less of the tire in contact with the ground. For example, road bikes are made to go fast, and they typically have the highest air pressure in their tires. The less your tires flatten, the smaller rolling resistance you'll face, and the faster you'll go! 

To sum up...

Learning about forces is just like riding a bike. Once you get the hang of it, it’s easy! So the next time you’ve got a holiday dinner waiting for you and you’re racing the clock on your bike to get home, what should you do? First, take a minute to empty your backpack of anything heavy. Then, pump up your tires. Finally, while you are riding, crouch down low over your handlebars. These tips and tricks will ensure you don’t miss a bite!

Did you know?

Recumbent bicycles (the ones that look like the rider is lying on their back) are more aerodynamic and have less air resistance than a regular bicycle. That’s why the Union Cycliste Internationale has banned these types of bikes from world speed record competitions. Their shape gives them too much of an advantage!