Bicycle gear ratios vs force required

This determines the gear ratio and therefore, how much force is required to pedal. In summary, the gear ratio on a bicycle is affected by the size of the chain wheel and sprocket, with a larger chain wheel making it easier to pedal and a larger sprocket making it harder. The gear ratio is determined by the number of teeth on each component, known as the 'torque multiplier'.
  • #1
Fatrobo
1
0
Evening all,

I am in the middle of trying to understand the physics behind how gear ratios work on a bicycle.

I have a typical road bike with a rear 10 speed sprocket and 2 front chain rings. What i am trying to understand is when you switch to a larger cog in the back it becomes easier to pedal but when you switch to the larger cog at the front it becomes harder to pedal.

I was under the impresion it has to do with the number of teeth on the cog doing the work but obviously I am wrong in this theory.

Any help would be much appeciated.
 
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  • #2
A bigger chain wheel causes the wheel to spin faster. A bigger sprocket causes the rear wheel to spin slower.

The 'torque multiplier' is the ratio of the number of teeth on the chain wheel to the number of teeth on the sprocket.
 

1. What is a bicycle gear ratio?

A bicycle gear ratio is the numerical representation of the relationship between the number of teeth on two gears. It shows how many times the smaller gear must rotate to equal one rotation of the larger gear.

2. How does gear ratio affect the force required to pedal a bicycle?

The gear ratio directly affects the force required to pedal a bicycle. A higher gear ratio means a harder gear, which requires more force to pedal but allows for a higher speed. A lower gear ratio means an easier gear, which requires less force to pedal but allows for a lower speed.

3. What is the ideal gear ratio for different types of riding?

The ideal gear ratio depends on the type of riding and terrain. For flat or downhill terrain, a higher gear ratio is preferred for faster speeds. For uphill terrain, a lower gear ratio is preferred for easier pedaling. Mountain biking typically requires a range of gear ratios to accommodate varying terrain.

4. Can changing the gear ratio improve performance?

Yes, changing the gear ratio can improve performance. By adjusting the gear ratio, a cyclist can find the ideal balance between force required and speed. This can result in improved efficiency, endurance, and overall performance.

5. How do I calculate the gear ratio on my bicycle?

To calculate the gear ratio on a bicycle, divide the number of teeth on the front chainring by the number of teeth on the rear cassette. For example, if the front chainring has 40 teeth and the rear cassette has 20 teeth, the gear ratio would be 2:1. This means the rear wheel would rotate twice for every one rotation of the pedals.

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