Fat bikes

dhunley1

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Jan 5, 2016
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582
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Michigan
Gotta love being able to combine two hobbies! Fenix BC21R in the front and a cheap Cateye in the rear. The dual distance beam on the Fenix is very nice. Lights up the ground directly in front of you, but can still cover some distance.

 

blah9

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Mar 10, 2011
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2,055
Yeah, looking good! Nothing like a nice night bike ride with some quality lights and fresh air.
 

harro

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Dec 5, 2009
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894
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Northern Victoria, Australia
Sorry for getting a bit off topic, but does anyone have any ideas on how to quiet a SQUEALING Shimano Deore rear disc/pad.
I have tried so far rubbing the pads on smooth concrete to rough the braking surface,
Thin cardboard behind the pad,
Remove the disc and spin it in the lathe tocheck for runout,
While there, rough up braking surface with 800 W&D,
Clean disc with solvent,

All this to no avail. The front is dead quiet, but the rear screams like a banshee. Next is a new set of Shimano pads, with thoughts that the originals may be contaminated with something. If that fails, i am pretty much out of ideas, any help greatly appreciated.

:hairpull:
 

blah9

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That's annoying. Sounds like you've used up most/all of my ideas.

I've been dealing with loud mechanical disc brakes on my cross bike and haven't been able to get them to quiet down yet too. I tried sanding the rotors but didn't mess with the pads actually. Not a bad idea.

Someone told me to go to a big hill and repeatedly go down fast and brake hard. Then keep pedaling against the brakes to heat them up a lot. Claimed it would help. I've tried it a bit and it may have helped a bit. Hasn't made it go away for me yet though.
 

harro

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Northern Victoria, Australia
That's annoying. Sounds like you've used up most/all of my ideas.

I've been dealing with loud mechanical disc brakes on my cross bike and haven't been able to get them to quiet down yet too. I tried sanding the rotors but didn't mess with the pads actually. Not a bad idea.

Someone told me to go to a big hill and repeatedly go down fast and brake hard. Then keep pedaling against the brakes to heat them up a lot. Claimed it would help. I've tried it a bit and it may have helped a bit. Hasn't made it go away for me yet though.

Thanks blah9, i have heard that as far as ' breaking the pads in '. Get them hotish in the manner you say, then swap front for rear and repeat the process. Helps to bed them in. As far as the squeal goes, i'm up to trying a new set of pads, to eliminate the possibility of contamination. The other thing i thought of since the last post i made, is to skew the calliper to the extent that the mounting bolts will allow, to see if uneven pad contact will do anything to quiet the noise. They are hydraulic operation, and i even checked for a leaky piston, but to no avail, all dry. Maybe i will go back to trying some sort of different packing behind the pads, but beyond that, i'm stumped. The annoying thing is the front brake is exactly the same, apart from a larger rotor, and its totally quiet. Haha, on a hill decent, at least the noise scares everything away from your path for probably 500 yards, and gives you a clear run.
 

blah9

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Mar 10, 2011
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Yeah that's a shame. Definitely let us know if you find something that works! Maybe I'll buy new pads for the cross bike too if that helps you.

My mountain bike with hydraulic brakes has been amazing so I wondered if the problem is that the cross bike is mechanical (I think one of the pads is even stationary if I'm not mistaken and only the other one moves to squeeze the rotor). But your situation actually gives me hope that it might be unrelated to that so maybe I should try harder to fix mine. Unfortunately I've been off the bikes a lot for a while but am trying to get back into things, so maybe I'll get it sorted soon.
 

NoNotAgain

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Jan 25, 2014
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Location
Blue Ridge Mountains, VA
I've had Shimano hydraulic disc brakes on my cross bike for many years. Mineral oil system.

The first thing I'd do is to drop the wheel, make sure the rotor is seated well against the hub and torque to either Shimano or hub manufacturers spec. Wipe the rotor with acetone or alcohol to remove any contaminates. Install the wheel in the drops and verify its sitting flat, then tighten the skewer. Spin wheel and check runout.

If the brakes are still howling, does your bike use the same caliper front and rear? If so, swap calipers, as it's possible the piston bore isn't bored 90 degrees to the surface.

The only thing I do to my rotors besides removing the grime of a ride is to sandwich a piece of gray Scotchbrite on both sides of the rotor and spin it from time to time. A quick acetone wipe and I'm back in business.
 

harro

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Eeeeeekkkk, i never thought of a piston not being square to the pad surface. The disc dialed fine in the bike, which squares away the disc to hub mounting surface. The disc also dialed fine in the lathe. As i was saying to blah9, i am going to try a new set of pads to eliminate contamination. If that doesnt work, then it may come down to substitution of the callipers. They are both BM-446 Deore, so that shouldnt be a worry. I clean the disc with an acetone, even getting into the clearing holes and making sure they are all clean. The annoying thing is my son's bike has the same brakes albeit with a slightly different hole pattern, and they work perfectly, front and rear. I will keep plodding away on this issue. I'll post it if i find the cause
Apologies to the OP and forum for getting off topic, but the suggestions recieved will hopefully help to sort this issue.

: Update :

Fitted a new set of pads to the calliper today. With the old set, and new, side by side, one of the two old appeared quite dark, even after a deep cut with a file, into the material. I couldn't say for certain that its contamination, but it was only in one of the two old pads. Anyway, got the new pads hot with pedalling against the brake, and so far so good. No noise, and a rear brake that feels more effective than it was, previously. Here's hopeing....
 
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