Internal (drum) brakes


Internal (drum) brake
Figure 1- Internal (drum) brake

The braking mechanism of an internal or drum brake is inside a hub, but it is actuated by a hand lever. The lever is connected to the brake by a cable. This system consists of several parts:

Brake lever

Brake cable and housing

Rear hub

Since they are part of the brake system, also read about brake levers.

Warning

Drum brakes get very hot during use and could burn skin.  Avoid touching the rear hub when hot.


Inspecting internal (drum) brakes

Before every ride squeeze the brake lever firmly. It should not be possible to pull the lever fully to the handlebar. Every month check that the brake cable clamp bolt is tight.

Every month check the brake cables on your bicycle for kinks, rust, broken strands, and frayed ends, and check the housing for bent ends, cuts, stretched coils, and wear. Replace any part which does not pass inspection.

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Adjusting internal (drum) brakes

To decrease lever movement

1. Loosen the locknut on the barrel adjuster and turn the barrel adjuster.
To increase the lever travel, turn the screw in (clockwise). To reduce the lever travel, turn the screw out (counter-clockwise).

2. After adjustment, tighten the locknut to hold this adjustment.

Rear wheel removal

To remove the rear wheel, you must first disconnect the shift and brake cables.

To disconnect the brake cable

Be careful not to touch the rear hub which may be hot from braking.

1. Press the cable carrier arm forward, and the cable clamp bolt rearward, so the bolt aligns with the larger diameter hole in the carrier.

2. Pull the cable clamp bolt outward to disengage it from the carrier.

3. Slide the brake cable stop forward to remove it from the brake arm.

4. Undo brake strap bolt.

To disconnect the shift cable

1. Put the shifter in 1st gear.

2. Pull the cable housing out of the shift cable housing stop.

3. Rotate the shift cable fixing bolt until the washer flats align with the slit in the cog joint bracket.

4. Remove the cable.

To unbolt the axle from the frame

When loosening and tightening the axle nuts, do so gradually, in small increments, to prevent effecting the bearing hub adjustment.

1. Slightly loosen the axle nut on one side of the hub by about 1/4 turn.

2. Slightly loosen the axle nut on the other side of the hub about 1/4 turn.

3. Continue loosening the axle nuts in small increments until you can slide the hub from the dropouts.

To install the wheel

1. Reverse the instructions for removing the wheel, including gradual tightening of the axle nuts.

2. Reverse the procedure to connect the brake cable.

3. Reverse the procedure to connect the shift cable.

4. Check that the gear cable tension is correctly adjusted.

5. Follow the Inspection procedures in the Wheels section of this chapter complete the installation.


Lubricating internal (drum) brakes

Whenever a brake cable is installed, lubricate the cable with a thin layer of synthetic bicycle grease or a similar lubricant.


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