cable attachment bolt
noodle
dust cover
brake arm attachment bolts
springs
spring adjustment screws, one on each brake arm, which help center the pads on the rim
pads, including spacers
V Brakes (Linear Pull Brakes)
V brakes were first mass marketed in the mid 1990s on mountain bikes. They stop much better than cantilever brakes and are easier to set up and maintain, rendering cantilevers obsolete. Now almost all mountain, hybrid and comfort bikes have either V brakes or disc brakes.
V Brake Parts
V brake systems include:
levers
cable and housing
V brakes, including brake arms and pads
Important components of V brake arms are:
cable attachment bolt
noodle
dust cover
brake arm attachment bolts
springs
spring adjustment screws, one on each brake arm, which help center the pads on the rim
pads, including spacers
V brake levers are different from cantilever brake levers. V brake levers pull more cable. Cantilever levers won't work well with V brakes, because V brakes need the extra cable travel. V brake levers work OK with cantilever brakes, though.
How V Brakes Work
Obviously, you pull the brake lever, which pulls the cable attached to the brake arms, which applies the pads to the rim, slowing the bike. When you release the brake lever, springs in the brake arms move the pads away from the rim.
Replace and Adjust V Brakes
Your wheel needs to be true before you try to adjust brakes, and the cable adjustment barrel on the brake lever should be screwed in all the way.
Tools needed:
preferably a work stand
hex wrenches, usually a 5 mm
small Phillips head screwdriver
cable cutter
The procedure to replace and adjust V brakes is:
1. Put the bike in a work stand.
2. Remove the cable from the cable attachment bolt on the brake arm, usually with a 5 mm hex wrench. (All brake threads are right-handed--bolts screw on clockwise and off counterclockwise.)
3. Remove the brake arms from the bike, usually with a 5 mm hex wrench.
4. Clean the brake bosses--where the brake arms attach to the frame or fork, and make sure they are screwed in all the way.
5. Inspect the cable and housing and replace if they are damaged. I would replace the cable just on general principles.
6. Install each new brake arm on the brake bosses. Tighten the bolt just kind of snugly--there's no need to torque down hard. Most brake arm attachment bolts have a touch of blue Loctite on the threads. If yours don't, apply a little bike specific grease to the bolt threads. There are probably 3 little holes on the brake bosses. Stick the end of the brake arm spring in the middle hole.
7. Insert the noodle and dust cover. (The dust cover is not necessary, so if you've lost it, don't sweat it.) over the end of the cable, and stick the end of the noodle in the receptacle on the brake arm.
8. Lightly attach the cable to the cable attachment bolt. You're only doing this as a convenience, so don't worry about precision.
Brake Adjustment and Brake Pad Installation
9. Align the brake pads. (If you are installing new brake pads, this is the procedure.)
a. Screw the barrel adjusters on the brake levers all the way in.
b. If you are installing new brake pads, take the old ones off and bolt the new ones in.
c. Loosen the nut holding the pad to the brake arm (usually with a 5 mm hex wrench), and using the brake arm as a lever push the brake pad against the rim. Position the pad against the rim so it is parallel to the rim's edge and close to the bottom edge but not hanging over it, and tighten the nut good and snug. If this seems awkward, it is--keep at it and try several techniques. You can do it.
The pads must not contact the tire when the tube is fully inflated.
d. Repeat step c for the second pad.
e. Loosen the cable attachment bolt, and pull the cable tight until both pads touch the rim. Let a tiny bit of cable slip through the bolt, 2 to 4 mm. Tighten the cable attachment bolt. Don't apply a lot of torque--those things do strip. Pull the brake lever. Do you like the way the lever pull feels? Readjust the cable until you like the feel.
10. Center the brake pads.
a. Locate the brake spring adjustment screws on the bottom exterior of the each brake arm. Usually they accept a Phillips head screwdriver, but sometimes take a very small hex wrench.
b. Look at each brake pad. Are they the same distance from the rim? And will the wheel rotate freely without rubbing the brake pads? Whoopee--you're done. If not, you need to center the pads.
c. On the brake arm with the pad closest to the rim, rotate the brake spring adjustment screw clockwise to tighten the spring tension and bring the brake pad outward. Fiddle with one or both screws until the pads are equidistant from the rim, and the wheel rotates freely without touching the pads.
11. Cable tension adjustment.
The feel of the brake lever and whether it engages early or late, or applies too little pressure, can be adjusted by changing the tension on the brake cable. One way is to tighten the cable at the cable attachment bolt on the brake arm (step 9 e). The easiest way is with the cable barrel adjustment bolt on the brake lever. Rotate the bolt counterclockwise to tighten the cable.
12. Cut the cable about 2 inches from the cable attachment bolt and crimp a cable tip on the end.
13. Test. Rotate the wheel and make sure the pads don't touch the tire or the rim. Squeeze the levers and make sure the pads fit on the rim, don't hang over the rim edge, and that there is absolutely no danger that they will plunge into the spokes. Take a test ride and be careful until you are sure the brakes work.
Brake Squeal
Squealing brakes brand you as a goober--you just can't let it happen. The cause of the squeal can be hard to locate. Here are some steps to prevent squeal:
Make sure the brake pads are tightly attached.
Snug the brake arms onto the brake bosses.
True the wheel and be sure the hub is snug.
Make sure the brake pads are parallel to the rim, or that the front part touches the rim slightly before the back part. This is called brake toe. Brake toe was necessary on cantilever brakes, but is usually not necessary on V brakes.
Clean and dry the rim and brake pads. Keep lube away from rims and pads.
Sand the brake pads, or rub them with a file.
Sand the rims with a fine grain sand paper.
Replace the brake pads.
V Brake Maintenance
Examine your brakes occasionally. Make corrections if the pads aren't parallel to the rim, are not centered, or if they hang over the rim edge or touch the tire. Replace the pads if they are worn. Tighten cable tension if needed. Occasionally drop a very small bit of bike specific lube on the exposed threads and on moving parts, but wipe off excess lubricant. Replace frayed or kinked cable or housing.
