Lab: How do Bikes Work

Name: Joel Alex

Course: ENGL 21007, Writing for Engineering

Date: 02/14/2025

This report deals with the physics of bicycle stability. It is inspired by the experiment conducted from the YouTube Channel Veritasium video, “Most People Don’t Know How Bikes Work.” In the video, Derek Muller interviews people, asking them to explain the physics of how bikes work. Most people incorrectly explain it, showing a misunderstanding of how bikes function.

In the video, Mr. Muller examines two common explanations for why bicycles stay upright: Gyroscopic Effect and the Trail/Caster Effect. The gyroscopic effect refers to the stability that is provided by the angular momentum of a spinning wheel. When wheels move, it resists orientation changes because of the conservation of angular momentum. Secondly, the Caster Effect is an measure of how far the steering axis is to the vertical axis, as viewed from the side. In the experiment, specifically designed bicycles with altered mechanics were used to address common misconceptions held by the public.

Bicycle stability is assumed by most people to depend mainly on the gyroscopic effect of the wheels. The experiment shows that bicycle stability is due to a combination of multiple interacting factors rather than due to a single factor. In the video, many people struggle to correctly describe the function that different parts of a bike have. The experiment involved designing and testing various bicycles with altered properties to better understand different bicycle stability factors.

The main modifications which were made were removing the gyroscopic effect, eliminating trail, and testing the effect that these changes had by asking participants to ride the altered bikes. “Removing the gyroscopic effect” refers to a bicycle with counter-rotating wheels. Mr. Muller also designed a bicycle, which was only able to turn in one direction. He asked participants to ride the altered bicycle and showed that it is impossible to ride this bicycle due to the principle of counter steering.

Counter steering is a technique that any bike rider instinctively knows. It simply deals with changing the direction of the bicycle. When a cyclist turns right, they must first momentarily steer left. This slight movement is necessary to change the bicycle’s balance. This causes the bike to lean right. This lean is necessary for the rider to turn right. This effect occurs because of the angular momentum present in the spinning wheels. Without the initial movement, it would be extremely harder to perform the turn. This often-unnoticed technique is discussed in the video and Mr. Muller shows this effect by asking participants to ride bicycles that are only able to turn in one direction. Bicycles were also tested for their ability to remain stable without a ride present. It was observed that bicycles are designed to be able to stay upright as long as they have constant kinetic energy.

References:

Veritasium. (2021). Most People Don’t Know How Bikes Work. Retrieved from https://www.youtube.com/watch?v=9cNmUNHSBac