You asked: How do the gears on my road bike actually work?

How your bike's gears trade effort for speed

The chain connects a big ring at the pedals to a small cog on the back wheel. The ratio of their teeth sets how many times the wheel turns for each turn of the pedals. Pick a ring and a cog below, then pedal to watch it happen.

The drivetrain

Try it
Drive side of a bicycle: rear wheel and cog on the left, chainring and crank on the right, joined by the chain.
Chainring, at the pedals
Pedal
Rear cog, on the wheel

Gear ratio

 

 

Per pedal turn

 

of road covered

Speed at 90 rpm

 

 

 

Every gear on this bike

22 gears

Each cell is a gear ratio: wheel turns per pedal turn. Tap one to load it into the diagram. Notice that several pairs land close together, which is why riders rarely use the big ring with the biggest cogs.

The numbers assume a compact 50 and 34 tooth crankset, an 11 to 32 eleven-speed cassette, and a 700 by 28 tire, which rolls about 2,136 mm per wheel turn.