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 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 a moving bicycle. And then, let’s look at some ways that you can decrease the magnitude of these forces so that you can go faster.
Gravitational pull on hills
Why is it harder to cycle up a hill than on flat ground? Because when you are biking up a hill, gravity is pushing you backwards down the hill. Gravity is the force that keeps us connected to the Earth and prevents us from floating away to outer space. The heavier you are, the greater the force of gravity acting on you. In other words, you can decrease the force of gravity pushing against you by making yourself lighter. For example, you can ride a lighter bike. You could also carry a lighter backpack (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 mass less than 15lbs, or 6.8 kg. That’s less than the mass of some human babies!
When you are biking, air resistance can seriously slow you down! The air is filled with particles, and you have to push them aside before you can 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.
The force of air resistance 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 less air particles that need to be pushed aside. This is why cyclists in races often hunch down low overtop of their handlebars.
Have you ever had to push a heavy object, such as a desk, across the ground? It’s a lot of work, isn’t it? This is because there are electromagnetic forces attracting the desk molecules to the ground molecules. 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 do have to overcome. It’s called rolling resistance.
Want to see how rolling resistance slows you down? Watch the wheels of someone else’s bike as they ride. If you look really closely, you will see that the wheels 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 wheels are filled with air. Higher air pressure makes them firmer - that is, they don't flatten as much. 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!
Talk about it!
Can any of these concepts help with other sports you play?