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-   -   Disc brake problems (https://www.bikeforums.net/mountain-biking/166945-disc-brake-problems.html)

Brian 01-23-06 07:25 PM

Anything else? :D

cryptid01 01-23-06 07:26 PM


Originally Posted by Expatriate
Your wheels flex when a sideways load is applied to them. Might not be a problem with a custom 36h wheelset with evenly tensioned spokes, but if you're running 32 spokes, and weigh a bit, your wheel will flex enough for the rotor to rub. No big deal.

The rotor's bolted to the hub. Spoke count or tension doesn't have anything to do with it.

cryptid01 01-23-06 07:27 PM


Originally Posted by Expatriate
Anything else? :D

Sorry to bust your bubble.

dkisluk 01-23-06 07:31 PM

then what is it????

Brian 01-23-06 07:36 PM


Originally Posted by gastro
The rotor's bolted to the hub. Spoke count or tension doesn't have anything to do with it.

So you're telling me that my huge dual crown fork flexes? I was told that my front disc rubs in hard corners due to wheel flex.

kakashisen77 01-23-06 07:44 PM

errr, what happened to my question?

hmmmm, i just riding around with my bike and i realized that there is the screeching sound yeh?

and when i just press down the front brake the slightest bit, the sound goes away. im not a bike mechanic so could someone please explain?

thanks

cryptid01 01-23-06 07:53 PM


Originally Posted by kakashisen77
errr, what happened to my question?

Chill. Someone who knows the answer to your problem (I don't) will reply.


To Expatriate, yes, your fork flexes.

Brian 01-23-06 08:08 PM


Originally Posted by gastro
To Expatriate, yes, your fork flexes.

So my dual crown with the huge stanchions and lowers, and the 20mm thru-axle flexes, not the wheel?

cryptid01 01-23-06 08:49 PM


Originally Posted by Expatriate
So my dual crown with the huge stanchions and lowers, and the 20mm thru-axle flexes, not the wheel?

No, your wheel flexes also.

It's just not the cause of the brake rub. Everything outboard of the hub body is irrelevant.

Brian 01-23-06 09:07 PM

I've got a dual crown, and I've also got a Headshok. I don't think either flexes. Next you're going to tell me a 9mm axle doesn't compress a bit when you tighten the QR. :D

badsac 01-30-06 06:34 AM

Gah. 2 rides on my new xtc2 with Juicy 5's and the front brake is squeaking like a mouse on acid already when I'm just riding along and not pulling on them. I swear these new fangled technologies are a pain in the arse. Give me the old canti's on my Trek anyday. Least you could run them for years and not worry about them and they'd still work good as new (which isn't that good but who cares? They always stopped me). I think I'm going to start a thread on why new bikes are bullarseproduct and everyone should be riding around on 80's vintage mountain bikes. :mad:

badsac 01-30-06 07:34 AM


Originally Posted by Expatriate
You should have at least room for a business card between your rotor and inboard pad.

Well my thing's got that. But the other side rubs. Do I take it that it shouldn't be?

mx_599 01-30-06 09:24 AM


Originally Posted by badsac
Well my thing's got that. But the other side rubs. Do I take it that it shouldn't be?

correct...there are multiple ways to alleviate your squeals. did you read all of the past brake posts from the past few weeks??

i use auto pad prep.

you need to start by making sure the pads are aligned....isn't this supposed to be easy with Avid**********

Brian 01-30-06 03:32 PM

Saccy, did you bed them properly? You need to do 20-40 stops to get them to break in.

badsac 01-30-06 04:57 PM

I'd say they'd be bedded. First ride was a pretty gentle one down a fair sized hill around here. Next ride where they started squeaking was on a hilly xc track.

Manual says loosening a couple of bolts it supposed to be for alignment. I just thought I'd make sure here that there is supposed to be no rub at all, sicne both my front and back brakes rub a bit, and any disks I've had on cars and motorbikes have always rubbed slightly. Thought it might just be a natural thing.

I was just hoping I didn't have to go dousing my disks in metho already since they're only 2 rides old. If I have to clean them every second ride then they'd be more likely getting some kero and a match tan metho.

BTW, you fellas say metho's a good cleaner. But doesn't the rubbish they put in it these days to stop me drinking it leave a residue?

mx_599 01-30-06 06:41 PM


Originally Posted by badsac
I'd say they'd be bedded. First ride was a pretty gentle one down a fair sized hill around here. Next ride where they started squeaking was on a hilly xc track.

Manual says loosening a couple of bolts it supposed to be for alignment. I just thought I'd make sure here that there is supposed to be no rub at all, sicne both my front and back brakes rub a bit, and any disks I've had on cars and motorbikes have always rubbed slightly. Thought it might just be a natural thing.

I was just hoping I didn't have to go dousing my disks in metho already since they're only 2 rides old. If I have to clean them every second ride then they'd be more likely getting some kero and a match tan metho.

BTW, you fellas say metho's a good cleaner. But doesn't the rubbish they put in it these days to stop me drinking it leave a residue?

maybe its okay...the pad retractors on my Hopes work just barely enough to get no rub...not sure if the pad retractors are designed to retract 'em all the way on yours.

brake cleaner works good...no residue :rolleyes:

Brian 01-30-06 07:37 PM

Metho should be ok, but I see no need to use it. Check to make sure the brakes aren't glazed. If they seem to work fine and alignment looks good, give them a few more rides. I guess your LBS doesn't offer the same free lifetime service that mine does?

Hopper 01-30-06 07:37 PM

To the constant squeaking problem, you have rotor rub..... get over it, most of the lazy bastards in Australia (me included) have slight rotor rub.

If you want to fix the problem, take off your disc caliper, make sure all the contact surfaces are clean and flush, re attach the caliper loosely, spin the wheel and lock up the brake. Now tighten all bolts (with brake still locked). Release the brake and voila, you have an aligned caliper. Now adjust the inboard pad as already mentioned. This should hopefully fix your problem. Another possible cause to this problem is that the actualt rotor itself is slightly warped (that is what is wrong with mine and it's not bad enough to need replacing). You can tell if this is the problem if the sound is not continual, but goes up and down in the loudness.

Whoever it was that was implying we Aussies only drink Fosters........... HELL NO. Gimme a Coopers or a nic Tasmanian beer over that crap. Fosters is the most famous Australian beer and no one here drinks it!

Hopper 01-30-06 07:41 PM


Originally Posted by Expatriate
Check to make sure the brakes aren't glazed.

I have been told on this forum that brakes on mountain bikes don't see the temperatures required to glaze a pad :rolleyes:

Also I have no idea how my mate did it, but he saved a pair of pads that he dropped in a bucket of mineral oil after he bled his brakes and went to put down the new pads he got. He put them down in the waste bucket :eek: He said he did a quick buzz with the blow torch (like 1 or 2 secs) then boiled them in water then cleaned them with metho. He finally sanded the surface a little bit (just to get a cross pattern) his brakes feel fine and he said he never needed a break in period for them:p

cryptid01 01-30-06 08:10 PM


Originally Posted by Hopper
I have been told on this forum that brakes on mountain bikes don't see the temperatures required to glaze a pad :rolleyes:


:eek:

Let's be careful out there, people.

badsac 01-30-06 08:14 PM


Originally Posted by Expatriate
Metho should be ok, but I see no need to use it. Check to make sure the brakes aren't glazed. If they seem to work fine and alignment looks good, give them a few more rides. I guess your LBS doesn't offer the same free lifetime service that mine does?

They offer 6 months on purchases, but they have to charge like a wounded bull after that or they wouldn;t make any money.



Originally Posted by Hopper
To the constant squeaking problem, you have rotor rub..... get over it, most of the lazy bastards in Australia (me included) have slight rotor rub.

So I should get used to riding with ear plugs? But yeah, I'll try the alignment thing although I think they should be pretty good already. I can see that I'll never have a great love of disk brakes on bikes though.

Now I've jsut got to figure out how to back the compression off on my RS Recon 351 fork. Thing is as tiring over small bumps as my old rigid. Hopefully I wont have to spring for a PopLoc Adjust lever or pull the forks apart. :(

mx_599 01-30-06 08:19 PM


Originally Posted by gastro
:eek:

Let's be careful out there, people.

i have said something to this effect. people throw around the glazing term and don't even know truly what they're talking about. (and i am going to cover my a$$ here, but i don't know i could give the exact "definition" of glazing...so don't ask me!! with my auto and motorcycle knowledge, i'd say i have a good idea...but i don't feel like being tested on it after a rough day)

i stand by what i have said. chances are, if you have just been doing cross country riding, your pads aren't glazed!

mtb-chop 01-30-06 08:26 PM


Originally Posted by Hopper
If you want to fix the problem, take off your disc caliper, make sure all the contact surfaces are clean and flush, re attach the caliper loosely, spin the wheel and lock up the brake. Now tighten all bolts (with brake still locked). Release the brake and voila, you have an aligned caliper.

That's basically the procedure for aligning Juicy 5 calipers. If you don't have the user's manual that came with the brakes, you can download it from Avid (SRAM) here.



Originally Posted by Hopper
Now adjust the inboard pad as already mentioned.

There's no separate adjustment for the inboard pad on Juicys. Once you adjust the alignment, you're done.

If you still have a little rub in one spot, you can experiment with aligning the caliper to different places on the rotor. Easiest way to do this is take not if where the valve stem is when you align the caliper, and if it still rubs a bit, see where in the tire rotation the rub occurs and change the spot where you align the caliper to. A slight warp developed in the Polygon rotor that came with my Juicy 7s and by re-aligning the caliper to a different place on the rotor, I got the rub to go away.

For badsac, they're great brakes - don't give up on them yet.

Brian 01-31-06 02:12 AM

Give me any brake with a rotor smaller than 203mm, and we can glaze them on one run with the tandem. If you like that blue look, we can burn the rotor a bit too. :D

badsac 01-31-06 04:50 AM

Brakes are for cats. You'd be much quicker down the hill if you'd leave off 'em. ;)


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