General Discussion Triathlon Talk » Squeaky rear brake Rss Feed  
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2005-08-04 8:54 PM

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Subject: Squeaky rear brake
I'm still learning the basics of bike maintenance, so I wanted to know the solution for a sqeaky rear brake. Today during my ride, everytime I braked hard the rear brake let out a high pitched squeak. Where is the best place to lube to avoid this? Also, I fully washed my bike this week, so that may have something to do with it. Thanks,

Derek


2005-08-04 9:11 PM
in reply to: #216996

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Subject: RE: Squeaky rear brake

Don't lube your brake pads, lubing reduces friction and friction is what makes brakes make you stop.

The squeal could be from your brakes toeing out so tha the heel of the pad is doning all the work. You need to toe the brakes in a little so that the whole pad hits square on the rim.

If you're starting to learn maintenance, get Zinn and the Art of Road Bike Maintenance. Excellent reference book.

2005-08-04 9:17 PM
in reply to: #216996

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Subject: RE: Squeaky rear brake

Edit....looks like Bear and I posted at the same time...ditto what he said.  My original post follows:

Sounds like a brake shoe "toe-in" issue but could also just be residue on pads and rim. Lube won't help you out and if you are describing it correctly would actually be disasterous.

I would first make sure there isn't any obvious residue on the rim's braking surface or on the pads themselves.  Next thing is that when your brake shoes contact the rims the front or forward tips of the pads should touch the rim before the back portion.  Adjusting the brake pads at this slight angle (toe-in) prevents them from vibrating when applied and causing the high pitched squeal.  It really is hard to explain without pictures as far as just how much difference there should be but it is not much.

Here is a great resource for quick reference.  It is the starting point for repairs and you can just click on the bike part you want information on (the blue mountain bike image).  It will take you to a sublist and you can scroll through the choice to find the one that matches your parts.  Lots of good pictures also!  Good luck.

http://www.parktool.com/repair_help/FAQindex.shtml

Michael



Edited by mmakbenton 2005-08-04 9:23 PM
2005-08-05 12:51 AM
in reply to: #216996

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Elite
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Subject: RE: Squeaky rear brake

My brakes don't just squeal-they SCREEEEEEEECH!  Front and back, clean or dirty, started when they were brand spanking new and never really quit for longer than a single ride.

I don't think they adjust for the toe in/out thing...if they do I can't see how.  Otherwise I've made sure they line up with the rim. 

Other suggestions would be gratefully appreciated ( I bet my bike club would send a thank you letter!)

2005-08-06 3:12 PM
in reply to: #216996

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Subject: RE: Squeaky rear brake
Thanks for the info guys.
2005-08-06 5:15 PM
in reply to: #217076

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Subject: RE: Squeaky rear brake

Depending on what model brakes you have there are three basic ways to adjust the toe-in.

1. Some type of dome shaped washer or "ball and socket" style joint in the shoe itself.  This allows you to losen the pad, pivot it so the front hits a tiny bit earlier and the tighten in that position.

2. Older brakes and cheaper brakes (department store quality) are thin and flexible enough that you actually can twist the brake arms so the pad is at a slight angle.  Park actually sells a tool to that makes doing this easy but any pliers with some padding under them would do the trick.  DON'T try this one with nicer or modern brakes as you will probably "brake" them. :-)

3. Using an emory (sp?) board or piece of sandpaper you can lightly file the brake pad so it doesn't all contact the rim at the same time.  Lightly sanding your pads is also a good idea in order to remove any dried up residue. Don't need to do it very often but it helps remove any glaze that is evident by shiny pads.

I just eyeball it when I do it but somewhere I heard that you can take a folded business card and "pinch it" between the rim and the rear half of the pad with the brakes on.  While holding the brake on with the card under the rear half of the pad you then tighten the pads thus setting up the angle.  Make sense?

Michael



2005-08-06 6:12 PM
in reply to: #216996

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Subject: RE: Squeaky rear brake
Another thing that works great for cleaning your brake pads is rubbing alcohol. After a lot of use, your pads will get a glassy, irridescent coating on the surface, and there will be little tiny splinters of metal stuck in them from the rims. I use a dental tool or something similar to pick out the metal bits, then rub the shiny coating off with Alcohol. It doesn't take much, and it comes right off. It also softens the pads a bit.

Don't lube anything. If anything it could be something like lube that is causing the squeeling. Wipe off your rims and see if it goes away, otherwise you probably need to toe the pads.

Some people think brake squeel is a bad thing. Yes, it is annoying, but usually it means that your brakes working really well.
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