The brakes are the most important part of our bikes and must always be kept in perfect condition, both front and rear.
Let's see how they work and what needs to be done to have a braking system always in perfect order, also checking the discs well after many kilometers of use and replacing them when they start to deteriorate.
The brakes installed in one motorcycle they are in most cases of the hydraulic type, which means that the braking force of these components is due to the pressure exerted by the braking fluid.
This braking fluid, contained in a special reservoir near the handlebar, is placed under pressure by activating the brake lever. This causes this fluid to be pumped into the pipes up to the calipers through a special cylinder. Once reached, the brake fluid will press on the calipers, which in turn will cause the brake pads, exerting a frictional force, to decelerate and stop the bike. As you can see, the principle that regulates the braking system of a motorcycle is in its broad lines very similar to that of cars: even here the braking is due to the friction force that the pads exert on the brake disc.
A disc is installed on each wheel of the motorcycle, which, just like the pads, tends to wear out over time and must be replaced. We proceed in this context to briefly explain the most important characteristics of this component. In general, a basic distinction is made between fixed disks, also called standard, and floating disks, also known as floating ones. The former are so called as they are forged in a single piece, while in the latter only the internal part is fixed and the external one is mobile.
The discs of the motorcycle, usually made of stainless steel, are equipped with holes, which are used to dissipate heat, and in some cases also with grooves, designed to facilitate the dispersion of rainwater. Let's take a practical example, illustrating the characteristics of a specific brake.
The fixed gold brake disc BREMBO front disc 68B407G5 has a diameter of 300 mm, a thickness of 5 mm and an internal diameter of 105 mm. The component is equipped with 6 fixing holes of 120 mm in diameter and with a bore of 6,5 mm. This type of brake disc is especially compatible with the following marche: Aprilia (model Pegaso 125, 600 and 650); BMW (G650) and Husqavarna (TR650).
Returning to the general characteristics of these accessories, the fixed discs have the advantage of being cheaper and, being forged in a single piece, they can be easily cleaned with special degreasing products. The disadvantage of their installation lies in their weight, which is higher than that of floating discs. The latter consist, as mentioned above, of an external part, which comes into contact with the brake pads, made of stainless steel, and an internal part, fixed to the wheel, made of aluminum. The two parts are held together by special rivets. The advantage of floating discs lies in a lower weight and greater effectiveness in braking maneuvers, also linked to their high capacity to dissipate heat. Obviously these discs are more expensive than fixed ones.
The replacement of the brake discs of the motorcycle must be evaluated in principle once the mileage has been reached 30.000-35.000 km. The duration of these components, however, depends a lot on the driving style and the quality of the roads traveled.
Finally, we recommend that you carefully inquire about the model compatible with your motorcycle, before purchasing these accessories. Information about this can be found in the appropriate motorcycle booklet or even by doing a search on the internet.