Mechanical Disc Brake Installation and Adjustment
This tutorial will explain how to install and adjust your mechanical disc brakes. We’ll use Avid mechanical disc brakes in the example. (Since disc brake setup varies by brand, see your instruction manual for specific details on your brakes.)
- 2.5 and 5mm Hex wrenches
- T25 Torx wrench
- Torque wrench
- Cable cutters
1. Install the rotor.
Start by mounting the rotor to the hub using six T25 Torx bolts. Make sure the rotor is facing the correct direction (arrow points in rotation direction, and logo should face outward.)
Tighten these bolts to the proper torque.
2. Install the caliper.
Mount the caliper and mounting brackets to the disc tabs on your frame or fork (for International Standard (IS) mount.)
Tighten the M6 bolts, securing the mounting brackets, to the proper torque.
(But do not tighten the Caliper Positioning System (CPS) bolts yet.)
3. Put wheel on bike.
Now you can put the wheel on the bike and tighten the quick release.
4. Align and true the caliper.
Turn the inboard and outboard pad adjusting knobs (the red dials) clockwise, squeezing the rotor between the brake pads.
The rotor should be roughly centered in the caliper body.
5. Tighten caliper.
Tighten the two CPS bolts that attach the caliper to the mounting bracket.
Tighten each bolt a little at a time, repeating until each is at the specified torque.
6. Install cable.
Install the brake cable, starting at the brake lever, and pass it through the anchor bolt on the disc caliper’s actuating arm. Pull the cable taut, and tighten the cable anchor bolt to the specified torque.
You can use the barrel adjuster at the brake lever to remove any remaining cable slack.
*Use a quality brake cable and housing when you do this. The better the housing, the better the braking performance. (A sealed, compressionless housing like Nokon is great, if you can afford it.)
*Quick tip: No more than 3/4″ of cable should extend beyond the anchor bolt. Any longer and it may get caught in the rotor unintentionally, when you least expect it, causing you to wreck.
7. Adjust brake pads.
Turn both pad adjustment knobs counterclockwise until desired pad/rotor clearance is achieved (approximately 2 or 3 clicks each). The disc should be able to spin without rubbing, and the lever pull (i.e. brake lever feel) should be comfortable.
*Tip from Avid: Only use the barrel adjuster at the brake lever to adjust for cable slack. For lever throw, use the outboard adjustment knob. For brake pad wear adjustment, use both the inboard AND outboard knobs.
For detailed installation instructions from Avid:
Avid BB7 Disc Instructions