Mountain Bike Reviews Forum banner
1 - 19 of 19 Posts

·
Enthusiast
Joined
·
5,360 Posts
Discussion Starter · #1 ·
Arrrrgh! How can something so wonderful suck so much? Disc brakes on cars are a solved problem. Ditto on motorcycles. Why can't it be that way with bicycles? Instead, the front brake on my two-month-old bike "chatters" and vibrates annoyingly, and the rear brake, when I hit that brake you'd think very demons of hell itself were on my tail -- the yowl is that bad.

Why in blazes do I have any problems at all? Why can't disc brakes on a bike "just work" like they do in a car or on a motorcycle?

The brakes are Avid Juicy 3s. The chattering on the front end began within the first week after purchase. I threw $20-something at a new set of pads. That seemed to solve the problem, but alas, it was not to be. The chattering is back. It's creeping back and getting worse by the day. I don't understand the problem. Should I get new pads again? Should I replace the rotors? Should I replace the whole thing?

And the howling on the rear, that just makes me want to drive a walmart bike. It's awful. My whole neighborhood knows when I'm riding. I'm actually embarrassed to hit my rear brake at night, for fear of waking people up. (Sometimes I have to commute at very odd hours -- 2:10 am last night, for example). I've cleaned the rotor a couple of times, and that gives some very temporary relief. I cleaned the rotor today, rode six blocks to the bank in back in blissful silence, but just as I arrived home the howling has begun again. It's not loud yet, but I've no doubt it will be shortly. The hounds of hell are after me, and I can't peddle fast enough!

What to do? I suppose I'll buy some different pads, and maybe I'll swap out that front rotor. It's all very frustrating though. Maybe I should just throw the brakes out completely and buy a whole new set.

There. I feel better. I just had to vent.
 

·
Registered
Joined
·
510 Posts
I've often wondered why some people seem to have tons of problems with disc brakes. I've been riding Hayes Mags since the early 2000's and have never had any major issues at all. In fact I didn't bleed my first set for 3 years. I know this doesn't solve your problems but I'm just making an observation. Maybe you can try to switch to semi-metallic pads if you are running sintered.

Some ideas:

What do you clean your rotors with?
Are the rotors warped?
Are the rotor mounting bolts properly torqued?
Are the calipers mounted properly and centered?
Are the pads installed correctly?
Did you 'break in' your new pads when you first got them?

good luck.
 

·
A wheelist
Joined
·
5,991 Posts
JonathanGennick said:
Arrrrgh! How can something so wonderful suck so much?
Don't generalise; be specific. "Why do MY disc brakes suck so much?" would have been the better question. My plethora of disc brakes don't suck at all. In fact they're perfect.

It could be your choice of brakes (you didn't ask me what to get!) or you could be making your own bad luck - those are the two main variables.

There are others too - those brakes on another frame might be 100% silent as in many cases it's a high-pitched frequency vibration that causes something on the bike (even the seat stays) to "tuning fork".

I worked on one set once that a front rotor swap was the cure. Try another rotor (borrow one, preferably another make) or even switching yours front to back.

Try filing off the leading edge of your pads as the slight reduction in pad size might change the vibration frequency enough. Try a hacksaw slit through the middle of the pad (to 3/4 depth) for the same effect.

Always ride with others so you can say to bystanders (with their hands on their ears) "It's him not me!". In other words - be creative.

But you probably feel a bit better for having ranted. :madman:
 

·
Enthusiast
Joined
·
5,360 Posts
Discussion Starter · #5 ·
Mike T. said:
But you probably feel a bit better for having ranted. :madman:
Oh yes. It was cathartic. Now I can go back to problem-solving. :thumbsup:

We have five bikes in our household with disc brakes. Four work perfectly. I don't know why the Juicy 3s on bike that I bought this spring are such an exception to the rule.

I'll get back to the troubleshooting today. I know there are plenty of threads that deal with howling brakes. (Are there any that deal with vibrating brakes?)
 

·
Enthusiast
Joined
·
5,360 Posts
Discussion Starter · #7 ·
vitaccop said:
What do you clean your rotors with?
I've been using White Lightening Clean Streak.

vitaccop said:
Are the rotors warped?
The do not appear to be warped, no. I gave the wheels a spin this morning and watched the rotors. I did not observe any warping.

vitaccop said:
Are the rotor mounting bolts properly torqued?
I have no way to check -- don't have a torque wrench yet. I would hope the bike shop would have put the bike together properly, but I can't rule out a mistake here.

vitaccop said:
Are the calipers mounted properly and centered?
Hmmmm.... The gap between rotor and pad looks to be a tad larger on the outer side of the rotor than on the inner side.

vitaccop said:
Are the pads installed correctly?
The LBS put them in. I don't see anything obviously wrong.

vitaccop said:
Did you 'break in' your new pads when you first got them?
The first time around, no. I just rode the bike. And I did tend to ride it fast down hills and then slam on the brakes at the last minute. I still prefer to ride downhills like that. Go fast + Stop fast = More fun :D .

The first time I had trouble with vibration on the front, I attributed it to my "go fast / stop fast" riding style. I had the LBS put on a new pad, and all was well. To break that second pad in, I made sure to take a few easy runs down the hill into town. I did not ride the brakes constantly all the way down, but I would lightly rub them for maybe a half-block at a time. Is that a reasonable break-in approach? All seemed fine for a few weeks, but lately I've been noticing vibration again.

One other thing: when the LBS replaced that front pads for me, they said that the old pads had glaze on them. They blamed the vibration on the glaze. They actually tried sanding the pads with sandpaper to improve things, but it took new pads.

Not sure when I'll be able to get in to the bike shop again to buy new pads. Between my work schedule and the distance involved, any trip to the LBS involves time off from work and pretty much burns up my entire evening. It is a non-trivial excursion. And my schedule this week might mean no trip in at all.
 

·
A wheelist
Joined
·
5,991 Posts
JonathanGennick said:
I know there are plenty of threads that deal with howling brakes. (Are there any that deal with vibrating brakes?)
I'm no scientist but I think disc brake generated high-frequency vibrations cause parts of the bike to howl - actually acting like a tuning fork. The trick is to cure the vibration or to band-aid the howl.
 

·
...idios...
Joined
·
5,662 Posts
Jonathon, you don't need a torque wrench to tighten bolts. As long as you're not ham-fisted about things, just use an appropriate wrench to double check the bolts holding the rotor and caliper. In my experience, the most usual, non-weather related cause for brake squeal is the pads touching the rotor at different times, ie. the rotor is not centred. It's very easy to fix with post-mounted calipers, you just loosen the bolts, centre the caliper over the rotor and tighten the bolts back up. IS mounts require shims and a little (or a lot!) more patience. Pads should be replaced when they are worn away, not when they are glazed. The harder the glaze, the coarser the sandpaper you'll need to get rid of it. Try swapping the pads over in the caliper (inner to outside) or try picking up some random cheap pads from ebay and see if the squeal goes. Even if the pads don't actually stop you, at least you'll have eliminated them from the equation.
If you follow the Maintenance Guides link in my signature, go to the Hope Mini Overhaul guide and you'll find the break-in process that I use.
Check bolts, check alignment and replace pads. It may sound stupid, but make sure the rotor is fitted so that it rotates in the right direction for the design. Most rotors will have an arrow marking their intended direction.
 

·
Registered
Joined
·
112 Posts
My bike came with juice 5's and have worked perfectly in the 250 offroad miles ive ridden with the bike, some of it in muddy conditions. The key part is cleaning them. I used a carnuba based cleaner/degreser that leaves stuff clean but not overly dry. If i use water only the brakes can squeal but with this stuff the brakes just work perfectly and make no sounds.
 

·
Registered
Joined
·
1,109 Posts
I know the "But you should try these pads..." stuff gets old, but I've been going over ALL the Juicy threads (old & new) since I've recently converted from BB7s to Juicys...

Consider getting an all-organic pad. Avid makes them now (the all-black pads), and it seems people are having very good results with them being quieter and less vibe-inducing (because of the softer pad compound). The downside is that they'll wear more quickly (esp in wet conditions) because they are softer organic.

Cheers, Chris
 

·
Enthusiast
Joined
·
5,360 Posts
Discussion Starter · #12 ·
I ran some errands on the bike over lunch today, and I'm much encouraged. The rear brake was mostly silent. Once or twice there was the hint of a yowl, but nothing so loud as to be bothersome. My cleaning late last night must have done some good after all. I'm just so hypersensitive to the noise right now that when I came home late last night and heard a hint of a yowl that I guess I got more discouraged than I should have.

Chris130, I'll see about trying those organic pads. My LBS mentioned those too, but they didn't have any in stock two weeks ago. I don't really care how fast the pads wear, so long as they wear within some vague zone of reasonableness. I just want the brakes to work.

The vibration up front is still a problem. That's actually the problem my LBS suggested that I try solving via an organic pad.
 

·
One Gear
Joined
·
1,078 Posts
non-weather related cause for brake squeal is the pads touching the rotor at different times, ie. the rotor is not centred. It's very easy to fix with post-mounted calipers, you just loosen the bolts, centre the caliper over the rotor and tighten the bolts back up. IS mounts require shims and a little (or a lot!) more patience
This worked great for me, on both front and rear brakes. Mine would howl on occasion, now they're quiet. Life's good.
 

·
Enthusiast
Joined
·
5,360 Posts
Discussion Starter · #15 ·
I appear to have been wrong about an improvement. During lunch yesterday, the brakes were quiet right up until I came home and brought the bike inside. I went out again after supper, and the howling is back. I don't understand what could change in such a short period of time.

Frustrating.
 

·
A wheelist
Joined
·
5,991 Posts
JonathanGennick said:
I appear to have been wrong about an improvement. During lunch yesterday, the brakes were quiet right up until I came home and brought the bike inside. I went out again after supper, and the howling is back. I don't understand what could change in such a short period of time.
Just how much supper did you eat? :D
 

·
Registered
Joined
·
510 Posts
If there is a drastic temperature change between outside and inside maybe the rotors and/or pads developed condensation on them when you take the bike outside. Then they would squeal because they are wet. Does it go away after a time period?
 

·
Enthusiast
Joined
·
5,360 Posts
Discussion Starter · #18 ·
Vitaccop. Good question. I have to park the bike outside all afternoon today, and all night too actually. I'll clean the rotors again first and report back on how things go.

Yesterday it did sprinkle now and then. Had the bike mostly indoors though.
 

·
Enthusiast
Joined
·
5,360 Posts
Discussion Starter · #19 ·
Took the bike back to the LBS today. Asked their mechanic to please find a solution for me. Asked if there was anything I was doing wrong. He said no, that I was doing nothing wrong, and that they've had no end of trouble with Avid Juicy brakes this year.

If I'm lucky, I'll get some relief under warranty. If I have to pay for new pads, or new rotors, or for some labor, that's fine too.
 
1 - 19 of 19 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top