Higher Gear Ratio Faster or Slower?

Last Updated on December 8, 2023 by Jaxon Mike

When it comes to bicycles and cars, gear ratios play an important role in determining the vehicle’s speed and acceleration. But it’s not always intuitive how gear ratios affect speed – does a higher gear ratio make you go faster or slower?

In this article, we’ll break down exactly what a gear ratio is, how it impacts wheel speed and torque, and when you want to use larger vs. smaller gear ratios.

What is a Gear Ratio?

To understand how gear ratios impact speed, we first need to understand what a gear ratio actually is.

Definition of a Gear Ratio

A gear ratio refers to the ratio between the number of teeth on two connected gears – for example, between the front chainring and rear cog on a bicycle. It can be calculated by dividing the number of teeth on the larger gear by the number of teeth on the smaller gear.

For example, if a front chainring has 50 teeth and the rear cog has 25 teeth, the gear ratio is 50/25 = 2.0.

Gear ratios are expressed in a few different ways:

• As a single number – e.g. 2.0
• As a ratio – e.g. 2:1 (read as “two to one”)
• As a percentage – e.g. 200%

The gear ratio provides a mechanical advantage, which allows tradeoffs between torque and speed.

How Gear Ratios Work?

On a bicycle, the front chainrings are connected to the rear cogs via the chain. When you pedal, you turn the front chainrings, which turn the rear cogs via the chain.

If the front chainring is bigger than the rear cog, it will turn the rear wheel faster – this is called gearing up. If the front chainring is smaller, it will turn the rear wheel more slowly – this is called gearing down.

The gear ratio between the chainrings and cog determines how much faster or slower the wheel turns compared to the pedaling speed. This is what ultimately determines your speed.

Next, we’ll look at how gear ratios specifically impact wheel speed and torque.

Gear Ratio and Wheel Speed

One of the main effects of gear ratio is how fast the wheels spin. This impacts your speed and acceleration.

Larger Gear = Slower Wheel Speed

A larger gear ratio (e.g. 3:1) causes the rear wheel to spin more slowly for each pedal revolution. This is because the larger front chainring turns the smaller rear cog more slowly.

For example, with a gear ratio of 3:1, the rear wheel makes 1 revolution for every 3 revolutions of the pedals. This results in a slower wheel speed.

Smaller Gear = Faster Wheel Speed

Conversely, a smaller gear ratio (e.g. 1:3) causes the rear wheel to spin more quickly for each pedal revolution.

With a 1:3 ratio, the rear wheel makes 3 revolutions for each single revolution of the pedals – resulting in a faster wheel speed.

So in terms of wheel speed alone, a higher (larger) gear ratio results in a slower speed, while a lower (smaller) gear ratio gives you more speed.

Gear Ratio and Torque

However, gear ratio doesn’t just affect speed – it also impacts the torque, or rotational force, applied to the wheels.

Larger Gear = More Torque

A larger gear ratio produces more torque at the wheel. This is because it provides greater leverage – the larger front chainring can turn the small rear cog with more force.

The tradeoff is that you have to pedal at a slower cadence to achieve this torque.

Smaller Gear = Less Torque

A smaller gear ratio produces less torque at the wheel because there is less leverage.

You compensate by pedaling faster to achieve a given speed. But this faster pedaling cadence results in less rotational force applied to the wheel.

Gear Ratio and Power

Gear ratio affects the relationship between speed and torque at the rear wheel. But your overall power output as the rider – a product of force and speed – remains the same.

Relationship Between Gear Ratio and Power

Your legs put out a certain amount of power at a given pedaling speed and force.

Gear ratio affects whether that power is converted into more torque (larger ratio) or more speed (smaller ratio) at the wheel.

But your overall power output remains constant at a given pedaling cadence. The gear ratio just determines the ratio of force to speed.

This pedaling force vs. speed relationship is why gear ratios are so important – they let you optimize the torque and speed as needed for different riding conditions.

When to Use Larger vs. Smaller Gear Ratios?

Knowing how gear ratio affects torque and speed, when should you use larger vs. smaller ratios?

Larger Gear Ratios – Starting and Climbing Hills

A larger front chainring and smaller rear cog provide more torque but less speed. This extra torque helps you accelerate from a stop and climb steep hills.

The lower speed requires more pedaling effort to go fast. But the extra torque helps overcome gravity and resistance when starting or climbing.

Smaller Gear Ratios – Higher Speeds

A smaller front chainring and larger rear cog provide less torque but more speed. This allows you to reach higher top speeds.

The lower torque requires pedaling faster to accelerate and maintain speed. But you can reach higher speeds with less pedaling effort once up to speed.

FAQs About Relationship Between Higher Gear Ratios and Speed

What is the easiest gear ratio to pedal?

The easiest gear ratios for pedaling are between 0.75:1 and 1:1. These provide a good balance of torque for hills and acceleration while still allowing relatively high speeds. Beginners often find gears in this range most comfortable.

What gear ratio is good for everyday riding?

For recreational riding and commuting on varied terrain, overall gear ratios between 0.9:1 and 2.5:1 provide a versatile range. Lower gears handle hills and acceleration, while higher gears allow 20+ mph on flats.

What gear ratio is best for speed?

To maximize top speed, you want gear ratios between 4:1 and 5:1. This gives you the right balance of torque from a stop but still lets you sustain 30+ mph before spinning out. Time trial and triathlon bikes often geared for top speed.

Should I get higher or lower gear ratios for hills?

For steep hills, you want lower gear ratios in the 0.5:1 to 1.5:1 range. These provide the torque needed to climb gradients while maintaining a steady, efficient cadence. Higher gear ratios risk bogging down and stalling on steep inclines.

Do higher or lower gear ratios increase acceleration?

Lower gear ratios around 1:1 maximize acceleration from a stop. The additional torque lets you get up to speed quickly. Higher gear ratios may cause slow acceleration due to a lack of rotational force. Time trial bikes gear specifically for rapid acceleration.

Conclusion

In summary, gear ratio has a key impact on torque, speed, and power:

• Larger gear ratio = slower wheel speed + more torque
• Smaller gear ratio = faster wheel speed + less torque
• Overall power remains constant – gear ratio affects torque/speed ratio

Use larger gear ratios for starting and climbing hills, and smaller ratios to reach higher top speeds. Understanding gear ratios is crucial for optimizing your riding for any conditions.