Disc brake adjustment and calibration

Among the various components of the bike, the braking system is an indispensable and vital part. In this article, let’s discuss the disc brake and learn how to adjust it. 

The principle of the disc brake

The hand brake lever transmits the force to the caliper piston through the brake wire or oil and acts on the brake pad, pushing the brake pad to the brake disc. Through the friction between the brake pad and disc, the kinetic energy is converted into heat energy to generate braking force.

Schematic diagram of cable pull disc brake caliper

The caliper type of disc brake

Disc brake calipers mainly include single-piston, double-piston, and four-piston types. Single-piston caliper is used for wire-pull disc brake. It generally has single and dual pad micro-adjustment knobs. Dual-piston and four-piston calipers are mainly used for hydraulic brakes and generally do not have pad micro-adjustment knobs. 

1. Adjustment of the single-piston caliper disc brake 

(1) Install the inner cable and outer pipe, use the inner cable to connect the brake lever, cable pipe and caliper. Tighten the inner cable, and fix it on the caliper. 

(2) Loosen the two mounting screws on the caliper (Be careful: there are not the adapter screws).

Adapter screw
Loosen the caliper mounting screws

(3) Determine whether the caliper has one or two brake pad micro-adjustment knobs.

Micro-adjustment knob caliper

(4) If it is a single micro-adjustment knob caliper, the knob is usually on the side close to the spokes. Turn the knob clockwise to make the brake pad clamp the brake disc. Keep the caliper position. The outer brake pad is against the disc. Turn the knob counterclockwise 1/8 to 1/2 turns, the inner brake pad is 0.2 to 0.4 mm away from the disc. Then squeeze the brake lever first, clamp the disc with the caliper, tighten the caliper mounting screw (not too tight), and then loosen the inner brake pad adjustment knob counterclockwise to minimize the distance between the inner brake pad and the disc. 

If it is a dual micro-adjustment knob caliper, tighten the outer knob clockwise to the tightest position, then withdraw one turn. After that tighten the inner knob clockwise to make the brake pad clamp the disc. Cross-fasten the caliper mounting screws (do not fasten them to the limiting position). Withdraw 1/8 to 1/2 turn counterclockwise when turning the inner and outer knobs.

Dual micro-adjustment knob caliper

(5) After adjusting the relative position of the brake pad and the disc, turn the wheel and check whether the pad and the disc are parallel. If not, make micro-adjustments. Pay attention to that the brake pad should not touch the disc.

(6) Fasten caliper fixed screws and ensure that the relative position of the caliper does not change during tightening.

(7) After debugging, test the brakes. You can adjust the brakes again through the brake lever and caliper tension micro-adjustment knob.

2. Adjustment of the dual-piston caliper disc brake

(1) Check whether the adapter is fastened to the front fork or frame.

(2) Loosen caliper fixed screws.

(3) Squeeze the brake lever tightly to make the brake pad clamp the disc. Fasten the caliper fixed screw.

Caliper adjustment

(4) After adjusting the relative position of the brake pad and the disc, release the brake lever and turn the wheel to check whether the brake pad and the disc are parallel. If not, make micro-adjustments. Pay attention to that the brake pad should not touch the disc.

(5) Fasten screws and lock the caliper.

If you have any ideas about this topic. Don’t hesitate to leave a message. We are looking forward to listening to your story.

 

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YouTube: https://youtu.be/M9FElvOdHdA

References:

[1] ‘Cycling Bible’ Editorial Board. Cycling Bible [M]. 1st Edition. Beijing: Machinery Industry Press, 2013.

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