At a fundamental level, all bicycle disc brakes operate the same way. Basically, the two pads are actuated by some mechanism that squeezes a rotor that is attached to the wheel.
Disc brake pads are usually made from powdered metal, plastic, and rubber. This composite combination of materials keeps the brake from locking up by allowing the pad to slowly burn away, keeping you safely behind the handlebars. Because the pad dissolves away, you will need to replace your brake pads every so often. Luckily, this is an easy operation.
First, you will need brake pads and the proper tools. For this quick change, you may need:
- 5 mm hex key – for the mounting screws (or 4mm, depending on your setup)
- razor knife – for opening those tricky packages
- small flathead screwdriver – for “encouragement”
- anti-seize compound – see explanation below
Using the appropriate 5mm (or 4mm) hex key, remove the brake.
Next, you will need to dial back to the calipers to their open-most position. For these Avid BB7s, both of the red knobs are turned counter-clockwise until they stop. Then, you need to squeeze the pads together and pull them out of the opening. Here, I am using the small screwdriver to “motivate” the pads out of the crevasse.
You may notice that these old pads still have some life in them. I decided to change these anyway because they had some rotor gouges and were really dirty. If you don’t want to change your pads, you can service them by grinding them down with fine grain sandpaper and cleaning them with rubbing alcohol before re-installation.
To install the new pads (or the old ones), simply reverse the removal process. Some brakes allow you to install the pads individually but the BB7 requires use of the “sandwich” method. Take the two new pads, sandwich them around the spring, and squeeze the pads together.
Keep a good hold on the sandwich, while minding the L and R indicators as marked on the pads; orient the brake receptacle properly. Then cram the brake pad sandwich in there and wriggle it around ’til it feels right. Each of the pads has an indentation for a nub on the calipers so you should be able to feel when the pads are nested properly. You can also test to see if the brake pads are seated properly by squeezing your brake levers a few times. If they’re in right they will not easily jiggle around or fall out.
Metals like aluminum, titanium, and magnesium are pretty reactive to the elements so I usually put a small bead of anti-seize on my mounting bolts to keep them from binding up or corroding over time. This is a good practice for almost all of your bolted components.
Now reattach your brake and get back out on the trail! Don’t forget to adjust and inspect your brakes before bombing down that next hill.