Once you’ve got the cable attached to the brake lever, and threaded through the outer casing, you’ll need to reconnect the cable to the brake unit. The procedure differs depending on whether you have link wire or a straddle cable. However, once you’ve connected the units, the procedure for adjusting the tension is the same.
Look at the disc in the middle of the two arms of the link wire. Of the two different slots the cable could go into, one makes it easy to push the cable through by lining up precisely with the section of outer casing. Once you’ve fed the cable through the link wire, push it across to sit in the other slot on the link wire disc and hang it at the right angle. Refit the nipple on the end of the link wire into the quick-release slot on the brake unit. Feed the brake cable under the cable clamp bolt and pull through until the blocks sit close to the rim without touching. Tighten the cable clamp bolt firmly, cut off any excess and fit a cable end. Pull the brakes firmly several times to settle things in place.
Back at the brake, push the cable through the hole in the pinch bolt. With a standard hanger, the assembly order is straddle hanger, cable, washer, nut. The height of the straddle hanger is crucial to the effectiveness of the brake. Push up the brake units so the blocks touch the rim and look carefully to estimate the correct hanger height. Clamp on the straddle hanger with the straddle wire arms at 90 degrees to each other. Firmly tighten the pinch bolt. This is critical, otherwise the straddle wire can slip down the brake cable and lock up the wheel.
Fit the straddle wire nipple into the slot on the brake unit, over the straddle hanger, and under the cable clamp bolt on the opposite side. Pull the straddle cable through so that the brakes are drawn in towards the rim. Ideally there should be about 2mm (1⁄8 inch) clearance on each side between the brake blocks and the rim. Hold the cable in place and tighten the cable clamp bolt firmly. Cut off any excess, leaving 5cm (2 inches) of spare cable, and then fit an end cap. Pull the brakes firmly several times to settle everything into place.
“When you spin the wheel, it should spin freely without dragging”
Adjusting the cable tension
Use the barrel-adjuster on the brake lever to fine-tune the adjustment. When you spin the wheel, it should spin freely without dragging, and it should lock when the brake lever is pulled halfway in toward the handlebars. If the blocks rub on the rim, you need to release tension in the cable. Roll the lockring away from the lever body and turn the barrel so it screws into the lever body (A) – clockwise, looking from the direction that the cable enters the lever. Test, repeat if necessary, then roll the lockring to wedge it against the lever body.
If the lever moves more than halfway to the handlebars before the brakes lock the wheel, you will need to increase the tension in the cable. Undo the lockring a couple of turns, then roll the barreladjuster out of the lever body (B) – anticlockwise as you look from the direction that the cable enters the lever. Test by squeezing the brake lever again, repeat as necessary, then roll the lockring back so that it wedges against the lever body.
You may find that you run out of barrel-adjuster – either it’s screwed completely into the body of the brake lever or it’s screwed so far out that it threatens to fall off. Set the barrel-adjuster so that about half the thread shows. Make a crude adjustment by going back to the cable clamp bolt on the brake unit, pulling cable through or letting cable out. Then go back and repeat the fine adjustment with the barrel-adjuster.
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES