Brakes
What is a Master Cylinder?
The pump at the lever that turns your hand or foot movement into hydraulic braking pressure.
Simplified animation — not to scale.
In plain English
Squeezing the brake lever, or pressing the rear pedal, pushes a piston inside the master cylinder, forcing brake fluid down the lines to the calipers.
A simple analogy
“The starting point of the whole brake system — every stop begins with this small pump.”
How it works
Lever or pedal movement pushes a piston through a sealed cylinder filled with brake fluid. Because fluid can't compress, that movement is transmitted almost instantly to the caliper pistons at the other end of the line, multiplying your hand or foot force into serious clamping pressure.
Signs of trouble
- ⚠Spongy or soft lever feel
- ⚠Lever sinking slowly to the bar under sustained pressure
- ⚠Fluid leaking near the lever or pedal mount
- ⚠Inconsistent brake feel between applications
Rough UK cost
£80–£300
Parts: £50–£220
Labour: £30–£100
Always get a written quote. Prices vary by bike, region, and parts brand.
Heads up: Motoautonomy is for general guidance only. If your bike is showing warning lights or behaving oddly, get it looked at by a qualified mechanic.