It is the name of the disc in the disc brake. A rotor can have different patterns, is about 1mm thick and has a diameter which depends on the size of your bike and your discipline (from 140 to 220 mm).
The stirrup is the part that holds the brake pads. It is located on the front or the back of the frame.
How does a disc brake work?
A disc brake is a brake system in which pads, placed in stirrups, are pushed against a disc to rub against it and brake. There are two types of disc brake: hydraulic and mechanical. When you brake with a hydraulic brake, the liquid between the brake lever and the stirrups (in the sleeve) pushes the pads against the disc so it rubs against it and brakes. When you brake with a mechanical brake, the pressure you put on the brake lever pulls a cable which pulls on the pads and makes them move against the disc.
Can I get a disc brake on my bike?
Not all bikes can be fitted with disc brakes. Disc brakes are quite new in the cycling world and are still under used in mainstream bikes. To fit a bike with a disc, two things have to be compatible: the frame (or fork if it is the front brake) and the wheel. The frame must have two notches for the stirrup to be fitted in. Frames with these notches are designed for disc brakes, but be careful: there might be a maximum size of disc that you are able to use. (The bigger the disc, the stronger the frame must be).
To fit a disc brake at the front, the fork has to be designed for it. Once again, the maximum disc size must be respected so that the fork won’t be weakened.
The wheels also have to be compatible: on the wheel’s hubs, there should be 6 holes for screws in a star formation. These holes will allow you to attach the rotor to the wheel.
Is a disc brake better than a v-brake?
Even if the wheel is bent, the brake will remain efficient. If it rains, the brake won’t lose much power. The main drawback of disc brakes is their price, as they are far more expensive than V-brakes. In addition, the frame, fork and wheels have to be compatible and stronger.
Hydraulic or mechanical disc brake?
Your choice will depend on your budget and on what you expect from your brakes. Hydraulic disc brakes are more expensive and have a better reputation for cycling or high-level touring with large rotors (which don’t heat up as much as they have a bigger surface). Hydraulic brakes also are more powerful and have a better progressivity, and a purge once in a while (once a year if you ride a lot) will allow you to ride safely.
If you don’t go for long rides or have no reason to pull strongly on your brakes too often, mechanical brakes will be enough. If properly fitted, they will be as efficient as hydraulic brakes. As well as the fitting, the performance of your mechanical brakes will also depend on their quality and brand.