V-brakes are the traditional type of mountain bike brakes. They feature a lever attached to a cable, which when depressed, causes pads on either side of the wheel to pinch the rim, resulting in friction which slows the wheel down. In contrast, hydraulic disc brakes feature a rotor disc which is positioned on the hub of the wheel, not the rim. When the brake lever is pulled, brake fluid inside the cables pushes the pistons and brake pads onto the rotor, which again creates friction and slows the bike down. Disc brakes require less pressure on the lever to stop the bike than V-brakes. Hydraulic disc brakes also offer more stopping power, increased modulation, and are more suited to downhill riding. For this reason, most modern mountain bikes have hydraulic disc brakes.