V-Brake ladies and gents: The following is for fine-tuning Shimano XT or XTR V-brakes and levers when you replace the pads and want to dial your brakes in. I set up my V-brakes by first screwing in the barrel adjuster all the way (but one turn) at the levers to make it easier to adjust them out when the pads wear. My final adjustment is also at the barrel for how much pull I want; and as my pads wear I may adjust them frequently. Usually I twist them out one or two turns after a wet/long ride has removed some brake pad.
I set up lever pull for my short fingers by screwing the set-screw on the front-top of the black lever housing (tiny little 2 mm allen, I think) in all the way, to keep the levers from moving so far away from the bar. I also take out one of the two plastic blocks in the lever itself (where the cable comes in) to reduce the amount of cable the lever pulls and make the brakes a little less grabby. I don't weigh much, so I don't need the mega-strong brake action of lots of cable pull like a clydesdale might.
Assuming the pad was adjusted correctly at the rim (you didn't rearrange the semi-spherical washers that hold the pad assembly to the parallel push mechanism did you? they are slightly different thicknesses so you can swap them around and set up the brakes on different width rims; if you don't put them back right, usually the adjustment will be all screwed up), you shouldn't have to adjust anything at the brake itself just because you put on new pads. That assumes the old ones were set up right and wore evenly. If they were not evenly worn and you adjusted them for toe-in, the new pads won't contact the rim squarely. Pads are easy to replace by pulling the cotter pin out with needle nose pliers, sliding old pad off, new pad in, and then looking through the cotter hole to make sure you can get the pin through before you start trying to put the cotter pin back in. A drop of tri-flow on the pin and a test for angle without the pad in may help you get the cotter through the lower hole. Be careful twisting the cotter, you can break the top off. XTR pads come packaged with new cotters, BTW.
Sometimes as the brakes get older, things get sloppy and they need adjustment. Use the allen on the nut on the side of the brake, where the pin from the pad assembly goes through the parallel push assembly next to the brake arm. Loosen the nut, push the brake arm in until the pad contacts the rim. Pushing the pad against the rim holds it in place while the nut is loose and makes adjustment really easy. Move the pad around until it is centered up-down on the braking surface of the rim and the contour on top follows the curve of the rim. Look at the brake from the front (or rear) and line up the pin on the pad assembly to be at right angles to the rim, not angled up or down. Tighten the nut firmly. Repeat on the other side, but check that both brakes match when you're done. Spin your tire and make sure it doesn't rub against the cotter pin holding in the brake pad. If it does, it will cut your tire wall and cause a blow-out. Check by pulling the levers as the wheel spins. Make sure the pad doesn't dive down towards the spokes either. If the pad moves on the rim, you probably don't have the pin at right angles to the braking surface.
When I put new pads on, they rub, because they are thicker than the old ones and I also took the slack out of the cable at the lever. I loosen the cable clamp at the brake, let it out about 5-10 mm, tighten the clamp again. This is the gross cable adjustment procedure I do first to try to get the clearance at the pads roughly right (check lever pull). Then, now here's the trick, there are two little tiny screws down near the pivot where the brake arms attach to the frame (or fork), that you screw IN to move the pad away from the rim. There's also a wire spring that pushes out against a pin, to move the pads away from the rim when you let go of the levers. Sometimes I pull the springs out from the pin and add a little tweak to make them stronger, and make sure both springs pull equally, then stick them back. Make sure the arms of the brakes are roughly parallel with each other, and point straight up, so that your brakes aren't offset to one side. Then, adjust the little tiny screws so your pads don't rub. Don't use these screws for major adjustments to pad clearance, use the barrel adjuster or cable clamp for that.
Last thing: check the aluminum noodle cable housing where it fits into the bracket at the brake lever. Make sure the noodle is fully seated in the bracket. If it's not fit in its spot properly, it will pull an extra 2-3 mm of cable and make your pads rub even if they were properly adjusted. This happens to me occasionally after I take the front wheel off for mounting on the car and am careless putting it back.
Really last thing: Older V brakes develop slop which can be lessened to a certain extent by inserting some special shims into the joint between the brake arm and parallel push assembly. These shims are either free (at your friendly local bike shop) or cost about 4 bucks. They come with instructions that are easy to follow, but you will need to remove your brakes from the bike to get at one screw and peel a sticker off that hides another. Count on taking your time with this project.More bike articles