Rim brakes are a type of braking system commonly found on bicycles. They work by using brake pads that press against the outer rim of the wheel to slow down or stop the bike. When the rider pulls the brake lever, the pads squeeze the rim, creating friction that reduces the wheel's speed. These brakes are generally lightweight and easy to maintain, making them popular for road and recreational bikes. However, their performance can be affected by wet or muddy conditions, as water or debris can reduce the friction between the brake pads and the rim.