BROOKLINEBIKER

Hi,
My bike has brand wheels and they screech brutally when brakes are applied. How can I fix this? Here is the background. I put new Mavic A719 Alu S6000 Wheels on my commuter bike last month. The rear wheel began to get screechy when braking with wet wheels over the last couple weeks. So, this past weekend I used pink Finish Line cleaner and paper towels to remove a substantial amount of grease and grime from the wheels. On today's commute, the noise was much worse/ awful and had spread to the front wheel as well. I had degreased the brake pads as well and felt no sharp objects or particles in them when I cleaned as well. The pads are a month old. Help!

BlazingPedals

Have you tried cleaning the rims with plain old dish soap? That Finish Line stuff looks like it has oils in it, which of course shouldn't be used on braking surfaces.

bpcyclist

Have you carefully examined the pads? Sometimes a little piece of metal can get stuck in the pad and will screech. Also, I am sure you have checked this, but when the pads are worn down too far, they will screech like mad. That's when it is time for new pads.

BROOKLINEBIKER

Hi, I haven't tried dish soap. Its winter where I am so I have no way to wash the soap off when it gets sudsy. I'll avoid the pink Finish Line going forward.

BROOKLINEBIKER

Thanks. I checked brake pads by hand last night. They felt fine. They are less than 1 month/100 miles old.

livedarklions

I had a set of wheels that would only get screechy when it was damp and cold. Water would condense on the rims until it got warm enough for that to stop happening. You could hear them from two blocks away. It was kind of fun since I knew it would go away shortly. Scared the hell out of pedestrians on MUPs, though.

AndrewJB

In my experience most brake screeching is due mis-aligned brake pads. You put on new wheels, you should loosen and reset the brake pads, making sure that there is a slight "toe-in" so the front of the pad contacts the rim first. A match-pack cover or folded business card thickness difference front to back is typical toe-in amount.

https://www.bikeman.com/bicycle-repa...ake-adjustment

Moe Zhoost

Detergent solution may work for rims, but I usually use acetone. It doesn't take much. How new are your pads? They tend to harden with age so if more than 5 years old you may want to replace them. As @AndrewJB above says, alignment is important. Make sure they land fully on the rim and have a slight toe-in so the front edge contacts the rim first. Sometimes it seems that nothing works. In those situations I do some hard braking stops from speed (apply both brakes please) which seems to help.

Good luck.

ThermionicScott 

What pads are you using? I've had squeal from clean rims and brand-new Kool-Stop salmon pads, precisely because they grabbed so well before releasing again, over and over. They just had to break in to stop squealing as much.

Drew Eckhardt 

Correctly toe in the pads. Assuming you have orbital mounting hardware, squeeze a brake with a dime under the rear of the pad, loosen the mounting hardware, and tighten it. Repeat with the other side.

DrIsotope

I've never toed-in a brake pad in my life.

BlazingPedals

I sure have. I've heard that the higher the quality of the calipers, the less need there is for toe-in, on the theory that squeal is caused by the caliper arms twisting and causing a high-frequency stop-slip condition at the pads. But in my experience it's always needed.

indyfabz

If the cantis on my touring/commuting bike are not toed in correctly they will squeal like crazy. As someone noted above, it can frighten pedestrians.

DrIsotope

Speaking as a user of only dual-pivot calipers, it doesn't matter. Pad material is of primary importance (the correct material for the wheel) and just getting the pads to make good contact with the rim.

I just loosen the bolts, squeeze the brake lever, and tighten the bolts. Aluminum wheels, carbon wheels, whatever.

jadocs

It works, I just did it a few weeks ago on my carbon rims. You still get the carbon wheel buzz but significantly less.

DrIsotope

I should also clarify that I've never had a brake make an "all the time" screech, or any sort of unwanted noises. My carbon wheels sound like a jet engine on spooldown when I brake hard, but that's just what the braking surface sounds like. My discs will make the usual "flock of chirpy birds" under very hard braking, but are otherwise quiet. My wife's bike is Koolstop salmon on aluminum brake tracks, and they don't make any noise at all, except when nice and wet, where they of course honk like an angry goose.

With modern dual-pivot calipers, toe-in is obviously unnecessary, or I would have found some sort of negative or drawback by now. I put 10,000+ miles on the same set of Koolstop pads, and they still had some life in them when I swapped wheelsets. I get ~7,500 miles out of each pair of front disc pads, and rotors usually last ~18,000 miles. I'm starting to think I just don't hammer and/or drag the brakes as much as other people do.

BobbyG

My snow bike has v-brakes, and the front right pad will squeal a little when it's wet and cold.

Phil_gretz

In the olden days, we would toe in the non-adjustable pads on aluminum sidepull calipers by twist bending the caliper arms with an adjustable wrench. Never broke one, thankfully.

And, the answer to the OP is toe in.

Drew Eckhardt 

I've had squeal a few times running dual pivot brakes with new pads and rims which went away with a toe in adjustment, including when using Campagnolo calipers with ball bearings between the arms so the pivots can be set snug with minimal drag.

BROOKLINEBIKER

Hi Moe,
I think cleaning is the way to go.
1. Are there safety issues associated with cleaning with acetone?
2. I did a cleaning with Pruss (sp?) alcohol last night and eliminated much of the screech. I ran out of alcohol when I started cleaning my front/left rim so I couldn't finish the cleaning of that area. The untreated area still screeches.

veganbikes

1. make sure everything is properly aligned and toe'd in and adjusted.
2. remove anything from your pads with a pick or something clean and not oily
3. file down brake pads to help remove any glazing
4. clean everything with isopropyl alcohol with a clean cloth (not one that has been cleaned with diesel or anything greasy)

I wouldn't use acetone or anything like that. Isopropyl alcohol works well and is pretty cheap and in some cases you might already have some. If not you can pick some up just about anywhere.I would go 70% and above.

Phil_gretz

Screeching Wheels would be my Indian name...

Bill in VA

Acetone like all really good cleaners that work quickly and remove grease and wax. It is toxic and very flammable. It evaporates very fast. Do not let it touch paint or especially any labels or graphics (so popular on modern rims) as they may wrinkle or craze. It may affect tires or tubes. I used to use it or lacquer thinner to remove tubular tire glue from rims.

For brakes you are on the right track, stick with 91% alcohol. I have also found that if you are using aluminum rims with machined braking surfaces, a perfectly clean new scotch-bright pad on the machined area alone, followed by alcohol gets it real clean. Braking surfaces should not be mirror smooth.

Litespud

try cleaning the brake tracks with isopropanol (70% or 91%, whichever is available) - effectively cleans and degreases, and leaves no residue. Can be done anywhere with paper towels

smashndash

When I had stock crappy tektro rim brakes and put on sticky kool stop pads, my bike would vibrate so hard that I thought it was going to disintegrate. It legitimately sounded like a train horn.

I then switched to a Shimano R7000 (read: stiffer) front brake with kool stop pads and my braking is now much better and DEAD silent.

I cannot recommend the R7000 brakes enough.

I also refuse to toe in my pads. I’ve found that there is a noticeable increase in squishiness associated with doing so, and that robs me of the ability to clamp down as hard on the brakes. Especially because I like/have to run my levers very close to the bars.