The Lever of the Drivetrain
A bicycle is the most efficient machine ever created by mankind. Its efficiency comes entirely from the drivetrain, which operates as a set of rotating levers.
The Gear Ratio dictates your mechanical advantage over the rear wheel. By changing gears, you can optimize your legs to either output massive torque for climbing a mountain or incredible rotational speed for flying down a highway.
Understanding the Ratio
Your gear ratio is a simple fraction: the number of teeth on your front gear (Chainring) divided by the number of teeth on your rear gear (Cog).
The Formula
Gear Ratio = Chainring Teeth / Cog Teeth
Where:
Chainring=
The gear attached to your pedalsCog=
The gear attached to your rear wheelInterpreting the Numbers
- A 3.0 Ratio (High Gear): Example: 54-tooth front, 18-tooth rear. For every single time you turn the pedals one full circle, the rear wheel spins exactly three times. This is incredibly hard to push, but yields massive top speed.
- A 1.0 Ratio (Low Gear): Example: 34-tooth front, 34-tooth rear. One turn of the pedals yields exactly one turn of the wheel. This provides a massive mechanical advantage, allowing you to easily spin up a 15% mountain gradient.