Brakes are the most important safety system. Any abnormality needs immediate attention.
Soft brakes with long travel may mean worn brake pads, old brake fluid, air in the lines or leaks. This is extremely dangerous.
Squeaking brakes often come from worn pads, hard material or dust. Loud knocking may signal loose calipers or brackets.
Shaking when braking at high speed usually means warped brake rotors. Frequent heavy braking causes overheating and deformation.
Brake pads are usually replaced every 30,000–60,000 km. Brake fluid needs changing every 2 years. Rotors last around 60,000–100,000 km.
Do not ride the brakes downhill. Use low gears to help control speed.
Brake safety is never something to ignore.