Jonathan Hanson 

I have a Thorn Nomad bicycle with Shimano hubs, Mavic XC717 rims, and Cane Creek cantilever brakes. The front has developed a bad squeal that I cannot exorcise. I've adjusted the toe-in, changed pads, cleaned the rims and burnished them with steel wool. Top-end pads, cheap pads—both squeal. Pads adjusted properly, pads adjusted so toed-in that only the leading half-inch contacts the rim. Short of buying a new front brake set I'm at a loss. Just walking the bike and squeezing the brake I can make them squeal; at speed they shriek.

Any thoughts or theories from experts?

Thanks . . .

Andrew R Stewart 

Change your perspective. Dirty up the pads. Toe out.Andy

dsbrantjr

If you have a stem- or steerer-mounted cable hanger, change it to a fork crown mount one, like this: https://www.amazon.com/Tektro-Front-.../dp/B006GHDRYC This will get rid of the root cause of canti brake shudder.
Here is a discussion of the phenomenon: Technical Q&A with Lennard Zinn: How to stop cyclocross brake chatter | VeloNews.com

2manybikes

This happened to me at about 6,000 miles on my Jamis touring bike with cantilever brakes. I put on new brake arms
And that stopped the noise.

cny-bikeman

It may be helpful to know how old the bike is and what kind of use/conditions to which it has been exposed. It's quite possible that with extreme use enough wear could occur in the pivots to indeed require new calipers.

Jonathan Hanson 

Thanks very much for all the input. I did lube the cantilever posts—no difference. The bike is about 6 years old and is ridden regularly, but not abused. I rode it across Israel last year.

I can just slightly rock the brake arms on the posts. So perhaps I do need new arms.

I'll read Lennard Zinn's article and see if anything there sounds relevant.

Iride01 

If you've been toeing your brake pads, then toe them in the opposite direction. Just to see......

wschruba

Since everyone else already said what you can do, don't do this (in the future) unless your rims are steel. The particles from the steel wool will embed into the softer aluminum track, and cause rust to bloom in it.

They make carborundum/rubber blocks that work well to clean rims without leaving deposits that can rust. Check under the name "sandlfex" (SandFlex Flexible Abrasive Blocks | Rockler Woodworking and Hardware for example). For bicycle work, 'fine' works great.

You might also find something similar in hobby shops that cater to model train builders, who use it to clean the (conductive) tracks.

Of course, you can buy the [more] expensive [and smaller] equivalents that Hozan or Mavic sell, if you would like to lighten your wallet a bit more.

evan326

Just to be sure, you cleaned the rim and pads very well with alcohol or brake cleaner?
Scrubbing the track and the pads with alcohol usually works for me.

Jonathan Hanson 

I did clean the rims; however, I've also been using steel wool, and I appreciate the heads-up on avoiding that in the future.

fietsbob

won't need to buy a bell, its now a feature.. not a flaw..



Magura HS 33 rim brakes, Kool stop Salmon pads ..

Jonathan Hanson 

It definitely gets attention right now.

noglider 

I knew a mechanic who said the cure is to oil the rims. Of course, I didn't take that seriously. Many years later, I was working on a neighborhood kid's bike shaped object (BSO), i.e. bike from a department store, and I couldn't get the squeal out. I oiled the rims. It worked, and braking power was not reduced. So as a last resort...

Jonathan Hanson 

Well, that's a novel approach! At this stage it's tempting. I'll report back when I've tried a few of these suggestions (short of 10W40 . . .).

noglider 

It's quite conceivable that it changes the composition of the brake pad which is why it eliminates the squealing. You could try oiling the rims, riding the bike a bit (with the precaution of assuming your brakes won't work on the first few applications), and then cleaning the rims with acetone. The oil remaining in the brake pads is all you need.

SquidPuppet

+

grayEZrider

+1 on this. But I have for years simply made a wipe-down the rim pass with whatever slightly grease-stained rag (from wiping hands after greasing bearings) and it's always worked!

CliffordK

One question, is front squeal worse than rear squeal?

It is always easy to drip a little chain oil on the rim, or perhaps even built up chain schmutz gets down to the rim.

evan326

+1

2manybikes

Softer pads stop better and are quieter. I could see the oil softening the pads. Wd-40 softens lever hoods. It cleans them quickly, but they need Pledge after to harden up a little.

I can't recommend it on brakes though. No brakes seems likely on the first ride.

CliffordK

Brakes are over-rated.

Especially those people who ride their brakes down hills

Am I getting old when half my break wear is on descents?

2manybikes

Safety is over rated as well. What's life without a little risk? Yes you're too old. This year I started using brakes on fast descents at night. I actually thought about my safety. I'm really old.

Retro Grouch 

How well do you like that neighbor kid?

Jonathan Hanson 

The rear brake (same model) does not squeal at all. I've considered swapping them to see what happened; I think I'll try that today and report.

noglider 

Good question. It was a slightly uncomfortable situation. I was teaching a bike repair class to kids. It was a summer day camp program. The kids left their bikes at the school overnight. I worked with the kid trying to get his brakes to work properly, but since it was a BSO, the bike did not respond normally. The brakes were so bad that unless they were adjusted super tight, they didn't work worth a damn. Toeing them in required loosening them, which made them work insufficiently, so I couldn't toe them in. After class, I kept working on the brakes, because I was beyond teaching him a useful lesson and trying to make the bike safe for him. Trying oil was a last ditch effort. I was surprised it worked but also glad. Some of these kids were poor, so "get a better bike" was not an answer. Even if they weren't poor, it's not appropriate for me to say to a kid who has to live within his parents' budget decisions.