BIKE helps: What does fading mean?
The braking force can decrease with prolonged use of the brake. This is known as "fading". There are two types of fading in hydraulic disc brakes: friction-induced and vapour-induced fading.
The two types of fading in disc brakes:
- Friction-related fading This can change the coefficient of friction. This is caused by the rising temperature at the contact point between the brake pads and brake disc. The result is a loss of braking force, whereby the driver actuates the lever more forcefully and does not feel any increase in braking force.
- Vapour-related fading This occurs when the brake fluid in the brake calliper and the brake line boils up. If a fluid is under high pressure, it only boils at higher temperatures. High pressure builds up when braking hard. This is why fading occurs primarily when the lever is released - the pressure then drops immediately. If the temperature is still above the normal boiling point, this sudden drop in pressure causes the fluid to boil up immediately. Result: Large bubbles form in the brake system. If the brakes are applied again, the lever travel to the handlebars is not sufficient to build up enough pressure. This leads to a loss of braking force.
What to do in case of fading?
Brake systems are designed to work at extreme temperatures. As a rule, friction-related fading occurs. You should therefore allow the brake to cool down before a further rise in temperature can cause vapour-related fading! In the event of vapour-related fading, the brake system must be completely bled.
