Fixing noisy V brakes

I suspect the pads are not correctly toed in. This problem will not correct itself over time.

If the pads are parallel to the rim then when you brake the leading edge of the pad bunches up a little and bounces off the rim. Fast. So you get squealing.

To avoid this you should adjust the pads so that the trailing edge is very slightly closer to the rim. Most packaged brake pads have this explained on the package, and conveniently the thickness of a bit of cardboard is a good distance to have the leading edge out from the rim. So the instructions usually say "the the package as a pad".

The easy way is to put something under the leading edge of the pad, squeeze the brake lever slightly, then do up the mounting bolts slightly. Hold the brake pad with one hand (to stop it rotating), the spanner or allen key in your other hand, and the brake lever with your gripping hand. If you're disadvantaged in the hand department I find that doing up the brake pad lightly while holding the brake lever, then releasing the lever and holding the pad to tighten it works.

The Park Tool website has an extended description.

Squealing can also happen if the brake calipers are a little loose from wear and tear. Toeing in will still help but may not completely eliminate the squeal.

My v-brakes squealed when applied and moaned when riding slow. I tried all of the toe in and out and different pads to no avail. One day I had the front wheel off and notice a very tiny bit of play in the axle. I tightened the bearing cup to snug but the wheel still spun freely. No more noise. Next day I did the same for the rear wheel and now my bike is stealth quiet.

I got a new wheel/rim and new brake pads and they had a terrible high-pitch squeak/squeal when braking. Tried all of the options suggested first - alcohol cleaning, toe-in - none helped much. Last option I read on some other web site is to use a wet rag with some commercial dish/pot cleaning powder - like Comet (US) or Vim (UK, Africa, elsewhere) - sprinkled on the rag; tried that - just a few dabs of the damp paste on either side of the wheel rims where the brakes would contact and the squeak went away.

Had the same problem, used a pot scrub cleaner for stainless steel on the rims - got rid of the squeak.