Surly Brake Hanger Stainless
This is, by far, our favourite cable hanger for rear cantilever brakes. Surly says this:
We couldn’t find a Cable Hanger we liked that would also fit our Constrictor Seatpost Clamp’s oversized bolt. So we made one. Long enough to eliminate kinked rear brake cables, large enough to fit over thick post clamp bolts, versatile enough to work with most other post clamps, and it’s even got an adjusting barrel. Also it’s stainless steel.