How Bike Gears Work

Bike Gears: Understanding How They Work

Bike gear systems have gotten complicated with all the options flying around. As someone who spent my first year of cycling afraid to shift — the lever clicks confused me, the chain made noises, and I didn’t understand why I needed all those gears — I learned everything there is to know about how this works. Today, I’ll share the simple explanation that made everything click.

What Gears Do

Probably should have led with this section, honestly. Gears change how hard you pedal relative to how fast the wheel turns. Low gears make pedaling easy but you don’t go as fast — good for hills. High gears require more effort but move you faster — good for flat ground and descents.

The goal is maintaining a comfortable pedaling effort (cadence) regardless of terrain.

The Basic Setup

Most bikes have chainrings at the front (attached to the pedals) and a cassette at the rear (on the back wheel). The chain connects them.

Front chainrings: Bigger = harder to pedal but faster. Smaller = easier to pedal but slower.

Rear cassette: Bigger sprockets = easier to pedal. Smaller sprockets = harder but faster.

That’s what makes understanding this endearing to us who struggled early on — it’s inverse at the rear compared to the front, which confuses people at first. But once you get it, it makes sense.

When to Shift

Shift before you need to. If you see a hill coming, shift to an easier gear before the climb starts. Shifting under heavy load strains the drivetrain and can cause dropped chains.

Aim for a steady cadence around 70-90 RPM. If you’re mashing slowly, shift easier. If you’re spinning too fast, shift harder.