We spend so much time worried about finding that next gear, we rarely invest in the things that can safely slow us down. Chew on that for a second.
Know the hardware: Cyclists realize that brake performance affects more than just injury prevention. Slowing to the perfect speed just before taking a corner, or rolling down rock steps when mountain biking, properly adjusted brakes maintain control that leads to better handling. There are generally two main forms of brakes, each having equal but opposite pros and cons.
Rim Brakes - The stopping power comes from calipers closing the brake pads on the side of the rim. Cheap, lightweight and simple, rim brakes are found on almost all road bikes. Road cycling involves a (usually) clean riding surface that the rider can see a significant distance. Contact between the track and the tire is minimized to allow less friction, and higher speeds. Rim brakes provide sufficient stopping power for small frames, and their slender and lightweight profile cuts back resistance. However, the rim can pick up water and debris in bad riding weather, which interferes with brake pads and braking power.
Disc Brakes - The major fundamental difference here is that the caliper clamps to a brake rotor in the middle of the wheel, not the side of the rim. This allows increased distance from the dirt and mud, and more braking contact without the mess. Rotors are usually made from hard alloys or ceramic materials to handle a heavier brake load, with calculated holes cut out for heat and debris dissipation. Disc brakes can be actuated by mechanical or hydraulic cables. All the extra equipment makes for a really heavy braking system, but when your life depends on it, there's no compromising. This is the main reason disc brakes are the standard on cliff-teetering, trail-jumping mountain bikes.
Maintenance and Installation difficulty (2-6/10): Healthy brakes have much to do with proper alignment to the wheel/rotor, and cable tension that's just right when the lever is squeezed. That being said, repairs and installations can vary in complexity and difficulty. Centering a rim brake caliper around the wheel takes 30 seconds, but installing a hydraulic disc brake system might be more headaches than you bargained for. We have a number of tutorials below to show what you're getting into before the disassembly begins.
Things you might need along the way: