Understanding Bicycle Gearing

Understanding bicycle gearing is as simple as understanding two terms—high and low.

High — The highest gear on a bike is achieved by combining the largest chainring in the front and the smallest cog in the rear. Pedaling higher gears will make the bike move faster. High gears are typically used when pedaling down hills.

Low — The lowest gear on a bike is achieved by combining the smallest chainring in the front and the largest cog in the rear. Pedaling a lower gear will move the bike at a slower speed. Low gears are typically used when climbing up hills.

When you’re deciding on a new bike it’s important to evaluate gearing. Will you be able to make it up your local climb without walking? Will you spin out sprinting for the city limit sign? 99 Spokes analyzes bike gearing and produces a visualization that makes it easy to see gearing differences in your comparison.

Here’s an example gearing comparison of two gravel bikes. It’s easy to see that they’ll both feel similar on the climbs but the Topstone has a higher top end, meaning it will pedal faster down hills.

We calculate an “Escape Velocity” for each bike, shown on the far right of the bar. This represents the bike speed when pedaling at 100 rotations per minute in the highest gear.

Great, now you get it, but how do I compare this to my current bike? I know what that feels on all my local rides… First try searching for your current bike and add it to the comparison. Can’t find it? Custom gearing? No worries! When you’re on a bike page you can enter your own custom gearing values for comparison.

Here you can see that the Stumpjumper has a lower gear than my current bike—it’s going to be easier to ride up steep hills on the Stumpjumper.