Drivetrain
What is a Chain?
The metal loop that carries your pedalling power to the back wheel.
Simplified schematic — not to scale.
In plain English
A chain is a row of tiny metal links and rollers, joined so it can bend around the chainrings and cassette. Push the pedals, and it drags the back wheel around with it.
A simple analogy
“A bicycle chain is a conveyor belt made of hinges — flexible enough to bend, strong enough to pull.”
How it works
Each link pivots on a pin, so the chain wraps smoothly around the toothed rings at both ends. Oil sits inside the rollers to stop them wearing out as they flex thousands of times per ride.
Signs of trouble
- ⚠Slipping or skipping under hard pedalling
- ⚠Rust or a dry, gritty feel
- ⚠Visible stiff links that won't bend smoothly
- ⚠A worn chain measures 'stretched' on a chain checker tool
Rough UK cost
£15 – £40 to replace, more for 12-speed specific chains
Always get a written quote. Prices vary by bike, region and parts brand.
Heads up: Bikeautonomy is for general guidance only. If your bike is behaving oddly or you're not confident, get it looked at by a qualified bike mechanic.