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-   -   Brake squeal that could wake the dead! (http://www.bikeforums.net/bicycle-mechanics/937199-brake-squeal-could-wake-dead.html)

f00dl3 03-07-14 04:51 PM

Brake squeal that could wake the dead!
 
I have a weird break problem on my Giant Cypress DX bicycle and was wondering if anyone may be able to provide tips/suggestions regarding it. This problem has been kind of bad lately and getting worse. Back in early January I had the bicycle overhauled at a LBS and when they overhauled it they put a new front wheel on. For several weeks after that the rims were squeaking. I asked them if that was normal and they stated that it was probably just the rims needing to get some break padding worn into them.

Break pads were / and still are fine. Probably at least 50-60% life left on them as they have only had a maybe 500 miles on them. Visually inspecting them shows they are not torn up or anything from road grit.

Fast forward about 3 weeks I had a nasty spill on the bike - wasn't hurt too badly due to the fact it was 18 and I had 2 layers on everywhere - but did get a sore hip for a week or so. Regardless - when the spill occurred it's almost like my front breaks "stuck" (The breaks are not getting stuck inside the cable housing - I am sure of that.) when I briefly squeezed them, causing me to lose control as I had 100% front breaking power but 0% rear breaking power going on. After getting the bike checked out I was on my way - but the squeeling was getting worse. To the point where cars could hear me and I could tell they were looking at me even though it was 15 and they had their windows rolled up!

I was going to go to the LBS to return the wheel and demand for them to give me a full refund on it and take it to another LBS, but I ended up wrecking the wheel by accidentally backing into my bicycle in the garage. (Oops!) Either way no harm done because the end result was the same just a bit more $.

Had the 2nd new wheel put on mid February. It worked great for about 2 weeks and then started squeeling again. Wednesday the squeeling was terrible to where even lightly pressing on the breaks caused it to do the "wake the undead" style screeeeeeech! Oddly enough, when I got back to the bike about 5 hours after my ride my front tire was completely flat. I put a new tube in and aired it up to 55 lbs - no squeaking. Aired it back up to the recommended 75-80 lbs when I got home to the floor pump, now it's squeaking again.

I can somewhat mitigate the problem by using the rear breaks 70/30, but unfortunately I still have to use the front breaks to fully stop and they still squeak no matter what. I'm also concerned whatever caused the squeaking caused the flat, and could potentially cause a front blowout which would be bad considering my average is about 15 MPH.

Going to take it to the bike shop for the 6th time for this problem on Monday (2nd time to the different bike shop.) - but this is getting old and I'm starting to wonder if there's something else wrong. One thing I have noticed is it seems when I press the breaks the actual metal cantilevers in the front have quite a bit of play - they move up the rim about 1.5-2 cms to the front of the bike when I break before locking out in that position. The rear breaks don't seem to do that as badly - maybe only half as much. I'm wondering if that could be the problem? Or maybe cheap wheels (they are StaTru brands - never had a problem before now with them though.) Or maybe the bike is starting to age - it has 5,500 miles on it now.

Kimmo 03-08-14 07:14 AM

Quote:

Originally Posted by f00dl3 (Post 16558418)
I have a weird break problem and was wondering if anyone may be able to provide tips/suggestions regarding it.

Yeah, we really, really hate it when people call brakes 'breaks'. Especially folks who can bandy around words like 'mitigate'. Also, they squeal.

It's a good thing you wrecked your wheel before stalking into the LBS to demand a new one; it wasn't the wheel's fault. Would've been an ugly scene.

And squealing brakes can't cause a flat, although you noticed lower tyre pressure can damp the squealing some, that's interesting.

As you've noticed, your brake calipers are crappy. The squealing can often be mitigated by setting the pads with some or even lots of toe-in, but if this doesn't do the trick some decent calipers should.

I'm assuming this is a MTB with V-brakes, but if it's quite old it'll have cantis as you say. If it's a newish bike with V-brakes, it's likely to have a stupid little spring in the noodle (the 90 bit at the end of the cable) on the front brake. If present, this is likely part of the problem, along with noobishness. The springs are put there by lawyers to protect the bike companies from noobs who can't modulate their front brakes, and squealing often goes away once a few hard stops have been performed, which a noob with a spring won't.

The best advice is to ditch the spring and get comfortable with the front brake. Practise stopping as hard as you can without going over the bars (hanging your weight off the back of the seat helps), and then practice using the front brake while turning - lightly at first, easing up to the point where bad things start to happen. The worst things actually happen at low speed, when the wheel can have a large angle. A momentary loss of grip at the front at higher speed is scary, but quite manageable with practice. A rear brake is totally optional (one of my bikes doesn't have one) because it has no more to offer when frontal weight transfer makes it lock up, at which point the front brake's just warming up. You should be able to use your front brake as hard as the conditions permit.

rydabent 03-08-14 08:25 AM

Get new brake pads. If they are "half worn" they are probably old and hard.

bkaapcke 03-08-14 03:24 PM

What brand of pads do you have now? bk

bikeman715 03-08-14 04:03 PM

Check and tighten any and all hardware on the bike 's brakes . Sand or replace the pads , but most of all try toeing them in , If you can't then have the LBS do it .

cny-bikeman 03-08-14 04:09 PM

If the brakes did not squeal before the wheel replacement and did afterward then it's either the wheel or something the shop did. There explanation is just plain wrong. Squealing is an symptom of vibration, and transfer of brake pad material to the rim typically causes, rather than relieves vibration. Either the rim had some sort of contamination on it or the brakes were misadjusted when the new wheel was installed. The shop should have corrected the problem when presented with it.

I would agree with most of the observations about front/rear brakes except that proper braking technique uses rear wheel braking as an early warning of overbraking. If the rear wheel starts skidding you need to let up slightly on the front or shift weight more rearward.

f00dl3 03-09-14 04:31 PM

Ok so I got it fixed. Turns out it was the break pads. They were generic Giant brand break pads I got in a 4 pack for $20 at the other LBS. Even though they were like only a month old when I got the first new wheel for some reason the sqeual is now nearly all gone with new KoolStop pads on front and Giant brand ones on back.

I am now REALLY pissed at the new LBS that gave me the overhaul AND new wheel, leaving me with a squeak. I really question their worksmanship if they didn't bother to think about mentioning the squeal and/or possibility that the break pads were just not working right.

JanMM 03-09-14 05:03 PM

B-R-A-K-E

Kool Stop pads have a great reputation.

Kimmo 03-10-14 05:45 AM

Quote:

Originally Posted by f00dl3 (Post 16563084)
Turns out it was the break pads.

http://stream1.gifsoup.com/view1/180...uuuuuuuu-o.gif

okane 03-10-14 06:33 AM

I am reading these posts while eating brakefast. Funny how that happens sometimes.

Kimmo 03-10-14 06:49 AM

It's like some kind of horrible mindworm.


f00dl3 03-20-14 07:23 AM

Or maybe not? The squeal is now back. Apparently ~120 miles was all it took to get the new break pads to squeal.

Just popped 2 brand spankin new tires on as well - as I was assuming that the front was going flat (yeah - happened again last week as well so 2 flats 2 weeks in a row) due to just wear (as I have had both tires about 2250 miles.)

Starting to think it's time to have the bike shop give the wheel a full check out and maybe the breaks as well - it shouldn't be doing this.

Homebrew01 03-20-14 08:10 AM

Are the pads toed in as suggested earlier ?? That means that the pads are not quite parallel to the rim, allowing the front of the pads (leading edge) to contact the rim a tiny bit before the rear. That could be the fix. Some pad holders have convex washer that allow that adjustment. The old-school method was to grab the caliper arm with a beefy wrench and bend it a bit.

noglider 03-20-14 10:39 AM

If you oil the rims, you might soften the BRAKE pads enough that they no longer vibrate at the current frequency. Despite how crazy this sounds, it will not make your BRAKES work any worse, because the pads will wipe the oil off the rims.

Breaks are different from brakes, which is why we spell them differently.

Chesterton 03-20-14 10:43 AM

I really doubt there is anything wrong with the wheel itself. Much more likely is the adjustment of the brakes, including toe-in.

Just to add some info for Kimmo, the Giant Cypress DX is a hybrid bike with MTB levers. I bought the same model in 2004 or 2005 and it has your typical linear pull brake with a noodle.

fietsbob 03-20-14 11:50 AM

crank-up the I Pod sound and it will be masked..

f00dl3 03-21-14 06:29 AM

Quote:

Originally Posted by Chesterton (Post 16595324)
I really doubt there is anything wrong with the wheel itself. Much more likely is the adjustment of the brakes, including toe-in.

Just to add some info for Kimmo, the Giant Cypress DX is a hybrid bike with MTB levers. I bought the same model in 2004 or 2005 and it has your typical linear pull brake with a noodle.

The brake pads I have always used for the front are KoolStop and are already pre-toed in (they are actually kind of curved at the tip towards the rim).

Ok now I get the spelling jokes. My bad. :)


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