Why does my cantilever brake squeal *nearly* all the time One of my bikes has cantilever brakes on chrome rims.  With dual compound Koolstop Eagle 2 pads braking is adequate and I can rely on the front brake at least in the dry.  

The back brake squeals like a stuck pig.  I could easily make it stop, but it's a much more effective warning than a bell or a shout when someone steps out in front, or when the lights change while passing stationary traffic. I like this feature.  

I'll restrict this to dry conditions as wet rims obviously change the behaviour. I can drag the brake lightly without squealing, or lock up the back wheel, but intermediate braking almost always produces a loud squeal for quite a range of pressure.  My issue is the almost.  This morning was dry, and I tested over a number of stops without using the front brake.  All were from around 20 km/h (10--15miles/hour) and were planned but fairly sharp stops. Excluding when I skidded the back wheel on a dirty bit of road, it squealed with no thought on about 80% of the stops.  On the other 20%, no modulation could produce a squeal.  Why?
I have cantilever brakes on my bike so I know the feeling. They just seem much more likely to squeal than any other type of brakes I've owned.  In the spring I had a bit of squealing. I cleaned off the rim, readjusted everything (cables, toe-in, etc.), and sanded down the brake pads a bit and everything seemed to be pretty good.

I also think it's something to do with the temperature.  Ever since the temperature started to drop, my front brake (also cantilever) has been squealing a lot. Even during the summer the first few times I would use my brakes they would squeal, but once they warmed up they seemed to work fine. I wonder if anybody makes a special brake shoe using a different rubber for cold weather braking.