Adjusting disc brakes on a road bike - Road bike disc: Adjustment and maintenance

Level of difficultyfor talented hobby mechanics

Tool:
- Hexagon socket
- Torque spanner
- bits
- Pointed pliers

Aids:
- Brake cleaner
- Cotton cloth

TIPS

STAY CLEAN
Keep brake discs and brake pads free of lubricants and care products such as chain oil and wax. If such agents get onto the disc, they must be removed immediately with special brake cleaner and an absorbent, clean cloth. Once the pads are dirty, there is no remedy and they must be replaced.

FIXED SCREWS
Most of the disc and brake calliper fixing bolts on the disc brakes are factory-fitted with adhesive. If you have unscrewed the screws, replace the adhesive. Check all bolts for tightness after 100 to 300 kilometres using a torque spanner.

FULL CONTAINER
If hydraulic brakes no longer open fully when riding downhill or in the blazing sun, the system may be overfilled. The bike dealer can help.

POWERFUL TENSIONERS
Disc brakes and lightweight tuning quick-releases do not go together. The wheels have to be tensioned in the dropouts with more force than normal wheels; only strong steel tensioners can do this.

HYDRAULIC DISC BRAKES

1

Grinding noises result from minimal contact between the
pad and disc. The brake calliper is usually not positioned correctly in relation to the disc. Asymmetrical braking forces cause the hubs to slip easily in the dropouts of the frame. Position the wheel and tighten the quick-release lever firmly.

2

Remove or open mechanical screw locking devices in the form of cotter pins, wires, plates,
etc. Loosen the two screws of the brake calliper mounting about one turn. Pull the brake lever so that the pads are in contact with the disc. Tighten the screws slightly.

3

Release the lever and check whether the windscreen grinds. If so, look in the window to see which side has more clearance and readjust if the screws have been loosened again. Several attempts may be necessary. Finally, tighten the screws with a torque spanner.

MECHANICAL DISC BRAKES

1

The wheel and brake calliper position must also be correct here. Mechanical brake callipers also have three adjustment devices. Use the screw towards the wheel to adjust the inner, fixed pad. Look through the display window and turn the pad close to the disc.

2

Adjust the outer pad. Turn the outer screw clockwise to get closer - or the other way round for more air. Keep pulling the brake lever until the lever travel is correct. The pads must not drag when the lever is stationary; it should have a clean pressure point after half the travel at the latest.

3

If necessary, adjust the cable on the adjuster directly on the saddle until the lever travel meets your requirements. To do this, loosen the lock nut and turn the knurled tension screw anti-clockwise. Finally, lock it. If the internal or external free travel does not fit, you will need to readjust.

EQUALISING WEAR AND CHANGING PADS

1

Hydraulic disc brakes automatically compensate for pad wear. With mechanical brakes, the lever travel is longer. Adjustments can be made at the adjusting screw of the brake cable and possibly also at the inner screw.

2

When the coating on the metal carrier has worn down to 0.5 millimetres, it must be replaced at the latest. Check the thickness in the inspection window. Unfortunately, the pads do not always wear evenly and in parallel, so you should measure them to be on the safe side.

3

Remove the wheel. For mechanical systems, completely turn back the pad adjustment screws and the tension adjustment. For hydraulic systems, push the plastic pad lock between the pads and press the pistons into the starting position.

4

Pull the safety split pin, if present, from the pad bolt and unscrew the bolt completely using the hexagon socket. Remove the brake pads.

5

Wipe the inside of the brake calliper clean with a cotton cloth. Remove stubborn dirt and any lubricants with special brake cleaner and an absorbent, clean cloth. Installation is carried out in reverse order.

6

For mechanical systems, readjust the pads and adjusting screws as described. With hydraulic systems, you must pull the brake lever repeatedly until a clean pressure point is achieved. Important: Always adjust the new brake pads according to the manufacturer's instructions.

Further workshop tips can be found in the standard work "The road bike workshop" retail price 14,90 Euro
TOUR author Dirk Zedler is the owner of www.zedler-institut.de

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