Question about disc brakes
 

I recently bought a new bike with disc brakes. In fact, I bought it just for the disc brakes. I wanted to avoid having to buy rims every 12-18 months, and I also got tired of squealing rim brakes in this wet climate. (And I wanted a new bike just because I was feeling self-indulgent.) I'm pretty happy with the disc brakes overall: they require much less cleaning/maintenance, and they have great stopping power even when soaking wet. However, they still make noise. They make faint scraping sounds when totally dry, and they do make a squeaking noise when wet or when I'm riding at low speeds. It's an improvement over rim brakes, but they're not the totally silent brakes I was hoping for when I bought this fairly expensive bike. Is this normal for disc brakes? Is there something wrong with them? Am I being unrealistic?

You're being unrealistic, particularly when they're wet. After all, you have two objects intentionally rubbing against each other under force at relatively high speeds. The level of noise can vary depending on the pad compound, the amount of grit on the rotor, etc, but in general you can expect at least some noise.

Seconded. I have discs on my touring/commuter, and they're not silent. Stopping power is awesome, which is the important part! :)

Didn't say which brakes you have, so hard to tell what is causing the noise and what steps you could take to improve. Could be cheap or mismatched rotors, could be contaminated pads. The rotors probably needs to be trued, which you can do with a special tool (Park makes one) or a large adjustable wrench. The truing tool bends the rotor closer to the center of the rotor, which works better. The calipers may need to be centered and adjusted.

I have SLX hydraulic disc brakes, use recommended rotors, and have perfectly trued the rotors, so no squealing and no scraping. If the pads are wet in the rain, fog or after rinsing the bike, they will squeal a little until they dry out after a few rotations.

Seasoned professionals have not been able to eliminate all noises from my Avid BB7's . Luckily that was not my goal. I don't trust myself to work on my disc brakes but I had no choice anymore, when I switched to drop bars. The new Tektro levers were short pull only, and the BB7 calipers were long pull. I didn't want to spend for short pull calipers, so I got some close out inline Travel Agents. The drag from them was immense and the brakes wouldn't return. I had to rig up a DIY brake booster. It works fine but now no LBS will touch the brakes. There have been a LOT of posts here recently featuring disc brake fanaticism and IMO it is so misplaced. V or Cantilever brakes can offer performance equal to mechanical discs at 1/4 the price, and when properly adjusted, and the wheels true, are totally silent. The work on them can be done by anyone. Bicycles do not need brakes worthy of 600cc motorcycles. That is what is showing up on some of the high end downhill bikes these days. Really? Who am I. If someone wants to spend what many people spend buying a used car, just on brakes for a commuter bicycle, again, who am I. Its the notion that it must be that way that annoys me. Humanity did just fine before mechanical disc brakes made the concept feasible to implement in "affordable" consumer bicycles. I've owned the tandem with the BB7's since 2005. That bike only comes out to play in the summer and only when there is a group ride on at the Tandem Club. Our other tandem which is our car and is in near daily use taking the wife to the train station has V-brakes. My commuter singles, cantilevers. Folders, v-brakes. If disc brakes were really that much better, it would be criminal of me to continue riding all those other bikes until they were upgraded. FWIW.

H

P.S. I'm sure some of my bikes have had the same rims for 12 years!

It sounds like bragi lives in a wet climate. I have the same problem with rim brakes - since I ride on gravel roads in the rain sometimes, it turns the brake pads into sandpaper.

On my road bike, if I only ride it in fair weather and on paved roads (or even occasional rain on paved roads), I'm sure my rims would last many years. On my hybrid, riding in salt and slush and ice and sand and gravel, I can go through a rim in 2 years.

I also went with discs for my foul weather/winter bike. I wouldn't consider rim brakes for a winter bike anymore. Rim brakes can completely fade out when riding in freezing rain. There's nothing quite like the feeling of pulling a brake lever and having nothing happen.

Disc brakes can be noisy, especially when wet. It's just one of those things. Maybe someone will make a rotor that plays tunes when you brake.

Fact of life, Disc brakes make noise, sometimes a lot of noise, sometimes none. Debris, dust, moisture, poor pad adjustment or wear, and they'll let you know they are there. It's a new bike right? I'd say ride it for a couple hundred miles and then take it to an LBS you really trust and have them dialed in. That can help, but it will never eliminate the possibility of noise.

Half my bikes have discs the other half are rim brakes. ALL my disc brakes make noise sometimes, NONE of my rim brakes do and it's all because they are properly adjusted and maintained, by me.

My disc brakes squeal too when they get some some crud splashed on them. It bugs me but beats pulling a break lever and not even slowing down a little, -which happened a couple times to me in the winter with rim brakes.

I'm glad we're seeing these kinds of posts because I find it reassuring that it's not just my brakes. It will also give potential disc brake owners a heads up as to what to expect from them. For a commuter I'm wondering if a more ideal combination might be a disc in the front and a drum or roller brake in the rear. If you just need to gradually slow down or stop in wet weather, you can use the rear brake without waking up the neighborhood. If you need to stop now, use the front.

I had that kind of set up for awhile the but the grease in the roller rake turned to molasses in cold weather and the bike didn't roll as well. Perhaps a drum brake?

cleaned the discs I had after a couple years and replaced the pads and then the sound was quieted down ..

BB7, now running with Kool Stop's organic compound pads .


the Shimano Roller brake is a greased hybrid somewhat coaster brake like in that it runs in grease which will harden in the cold.

the Sturmey Archer Drum brake hub is a dry friction pad , and is unaffected by cold weather .


The bike I break out when the road is Icy is an old MTB with drum brake hubs and studded tires .. that I leave on.

You can add me to the list of people whose disc brakes squeal and make noise. I don't really care about them making noises, as long as they stop me, that's all that matters.

Disc brakes should not make noise if properly adjusted.

Assuming your brake caliper is properly positioned here are some things that may help:

1. Make sure your wheel is properly seated and that the QR is tight.
2. File off any deformations or junk on your brake pads.
3. Make sure your pads are properly seated (there is typically a small dimple that is filled by a protrusion on the caliper).
4. Try switching to OEM or a different brand. (Pad thickness varies from manufacterer and I've had pads that were slightly too big when new.)
5. Try organic pads (sintered and metal tend to leave residue in the caliper that can cause squealing)
6. Clean the rotor with isopropanol or other mild solvent.
7. Check whether rotor needs to be trued.

Noise when wet is pretty common. Noise when dry should only be because of pad/rotor mismatch or contaminated pads.

First things I would do is make sure your calipers are bolted on straight(just cuz it's new doesn't mean it was set up right) and rotors are true. Look at the caliper from the rear,and make sure the caliper is straight on the rotor. There are two bolts that go into horizontal slots in the caliper mount;they should be lined up. If not,that's a sure sign the caliper is mounted crooked. Next look down into the caliper from the top or bottom(if the bike is upside-down). Hold the wheel by the spokes and slowly turn it while looking at the rotor between the pads. If the rotor moves to the side and touches a pad,it needs to be trued. To do this,turn the wheel until the rotor touches,then grab the spoke above it,and turn the wheel until that part of the rotor is out in the open(by holding the spoke you'll know where the spot is). Clamp an adjustable wrench to the rotor(DO NOT use pliers or a wrench with teeth,the teeth will score the rotor) and gently bend the rotor in the opposite direction from the side it was touching. Then rotate the rotor back into the caliper and see if it still touches. If it does,repeat bending a touch more. Once it's clear turn the wheel until you've checked the entire circumference of the rotor.

My OEM Tektro Novela mechanical disc brakes tended to squeal a great deal on my 29er, but its upgraded Shimano M445 hydraulic disc brakes don’t squeal. Its brake pads don’t drag, so they’re quite while cruising along. I wish I had gone to these hydraulic disc brakes a couple of years ago.

I'll check this out, thank you.

True the rotor

Seattle is as hilly as vancouver if u are going down a long hill dont drag them for a long time youll blue the rotor and boil the fluid then lose all braking. Stab then off works the best.

It should be said that its not just the water making rim brakes slippy on roads, its the oil from blacktop & off of vehicles that causes it. Pure water has an effect on friction, but oil tends to stick, not evaporate like water does.

Perhaps there is some device or something that could clean the crud off of rims or discs before the rim or disc passes through the squeezy part of the brake?

- Andy

I can't imagine any city having hills steep enough to mess up hydros. Unless you're commuting on a tandem up and down Pike's Peak,this isn't a real world issue.

A bike magazine tested some and managed to do exactly what i said while dragging them, blued the rotor boiled the fluid crashed intentionally to stop, but he was on a highway. But it is a real world issue the only brakes made light enought and sleek enough are shimano freeza unlessyou stick clunky 203mm on there is always the chance. Ill try and look up the article.

If not 1st hand observation, its what is called Hearsay in court .. they would subpoena the author to appear.


same with rim brakes ..

Hilly Astoria ( actually its one hill the town goes up and over it) ,,BB7 160 discs in a 406 wheel speedial levers, work fine ..

just the pad adjuster is Me.

Did you use the SA drum brakes on your old MTB? I've been thinking of building a wet weather bike with drum hubs, and it would be an old steel mtb. I was planning on disc, but the more I hear about the squealing, the less attractive they are, plus you can't just throw them on an old frame. Are there any drawbacks on the drum brakes, other than weight (which I don't really consider to be a problem) and having to do a little more work to take off the wheel?

I rebuilt a 1st years Stumpjumper sport frame .. I had the broken dropout replaced . with 2 new old ones . then found a fork , etc, etc.

One thing about the rear, ( i got the still made in UK 'Elite' Freewheel /drum combo, with a sealed bearing cartridge.)

the freewheel it takes is a 7 speed or 6 .. the axle F&R is 9mm ,, think its OK in a 130 frame, 135 maybe . I havent measured it .. or forgot.

recently the Sun Race owner of the brand offers a cassette drum combo

to make rear wheel changes a bit easier the strap has 2 sets of bolt holes .. one holds the strap on the chainstay.

for the other one I use a ball detent Pin with a ring on it , so I pull the pin then loosen the axle nuts .. .

the brake cable end has a barrel held with a set screw , it pops right off .. EZ just back off the long barrel adjuster a bit .



it does build up rather asymmetrically with the dish looking like more because the 10cm hub.flange around the drum on that side .

A drum IGH would be more dishless they make a drum brake 3,5& 8 speed ..

front one the arm fits in a slot on the strap on the fork blade . just loosen the nuts and disconnect the cable barrel .. & it sslips right out ,


One big Benefit is the drum brake easy modulation stops smoothly
as its wearing the studded tires .. not being a sudden skid isa good thing, on Ice.

Try organic brake pads. I find them generally quieter in wet weather.

Might oil also stick to pads? If so and if rubbing alcohol can remove oil from the rotors, I wonder what can clean oil off pads.

Tried. contaminated pads are pretty much shot. I take sandpaper to them and remove material down to clean compound.

erm...no.
a bike magazine beta-tested crappy road hydraulics on a steep descent in hawaii and the reviewer admitted dragging the brakes the whole time.

i've never "blued" a rotor or "boiled" mineral oil and i descend ~210,000 feet each year.