# Physics EE (Extended Essay) on Bicycle Stability

• manu101
In summary, a new Physics forum member is seeking guidance on their extended essay topic on the stability of bicycles. They are considering studying the bike with a rider or without, and are looking for suggestions on factors to vary. Several helpful links and a book recommendation are provided for further research.

#### manu101

Hello! I'm new to the Physics forums so I'm not too sure if this is the right place. But hopefully it is :)
Anyway, I'm currently an IB student studying Physics at higher level and decided that I was going to do my EE (extended essay), which is about 4000 words, on physics.

Since I really wanted to do something related to stability, with help from my supervisor I decided to look into the stability of a bicycles. Anyway, I need help with deciding a few things to ensure I have enough content to write about for 4000 words as well as to be able to score high on my EE.

I'm investigating on two independent variables, two factors that affect how stable a bicycle is by measuring probably how much time it can stand upright without falling to one side. Nevertheless, I was wondering whether studying the stability of a bike with a rider on it or "rider-less" is better. The thing is that I think that studying the stability of a bike with a rider on it would be better as there are more factors that can be varied compared to rider-less, however, I feel like there is human error as we cannot ensure that certain variables will remain constant throughout all the trials (I hope you are getting my point).

Also, I need help deciding on what factors I should vary (I need 2 factors) so as to make my EE interesting and not such a straight forward answer. Here are some of the factors that I'm thinking of:

With rider: pressure of air in the wheels, weight distribution, height of the seat and/or handle, distance between handle and seat, distance between hands on handle, weight of rider (probably won't use this), distance between feet, fork angle.

Rider-less: pressure of air in the wheels, height of seat and/or handle, distance between handle and seat, angle of the seat?, fork angle

^^please feel free to add to the list, I'm trying to make it so the factors are not so "direct" but must still be measurable

Thanks for taking the time to read my threat, I'm open to any suggestions! :)

Welcome to the PF.
manu101 said:
how stable a bicycle is by measuring probably how much time it can stand upright without falling to one side.
I'm pretty sure you mean "when rolling", not "when standing". Bikes fall over if they are not moving.

I'd vote for doing the analysis with a typical rider on the bike, since that is how they are used, and is the most important time for them to be stable. There have been some previous PF threads on the stability of bikes and motorcycles -- I will do a quick search to see if I can find a few to link to for you...

manu101
Here's a Sciam article on it too:

https://www.scientificamerican.com/article/the-bicycle-problem-that-nearly-broke-mathematics/

Be aware that this is not a trivial problem and that folks have been arguing over it for years. Its akin to how the Stradivarius violin got its hauntingly beautiful sound.

Sometimes I wonder how classical physics was able to evolve and yet not have a good understanding of this phenomena. Einstein used to ride around on a bike a lot and apparently never considered it.

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Get a copy of Bicycling Science Third Edition by David Gordon Wilson, and read Chapter 8: Steering and Balancing. Forty seven pages of everything you are looking for, and much more.

manu101 and berkeman
jrmichler said:
Get a copy of Bicycling Science Third Edition by David Gordon Wilson, and read Chapter 8: Steering and Balancing. Forty seven pages of everything you are looking for, and much more.

## What is the purpose of studying bicycle stability in physics?

Studying bicycle stability in physics allows us to understand the underlying principles and forces that contribute to a bicycle's ability to balance and maneuver. This knowledge can be applied to improve bicycle design and safety.

## What factors affect the stability of a bicycle?

The stability of a bicycle is affected by several factors, including the design and geometry of the bicycle frame, the distribution of weight on the bicycle, the speed and direction of travel, and external forces such as wind and surface conditions.

## How is bicycle stability quantified in physics?

In physics, bicycle stability is often quantified using the concept of "trail," which is the distance between the point where the front wheel touches the ground and the point where the steering axis intersects the ground. A larger trail generally results in a more stable bicycle.

## What are some common misconceptions about bicycle stability?

One common misconception about bicycle stability is that it is solely determined by the rider's ability to balance. In reality, the design and mechanics of the bicycle play a significant role in its stability. Another misconception is that a higher speed always results in better stability, when in fact, certain speeds can actually make a bicycle less stable.

## How can understanding bicycle stability in physics benefit society?

Studying bicycle stability in physics can benefit society in several ways. It can lead to advancements in bicycle design, making them safer and more efficient. It can also inform safety regulations and guidelines for cyclists, leading to fewer accidents and injuries. Additionally, understanding bicycle stability can also be applied to other modes of transportation, such as motorcycles and cars.