My wife has a Cannondale Quick. When we first got it for her, the brakes started squealing under hard braking. The LBS sanded the braking surface of the rims and put on Cool Stop Salmons. That solved the problem for about 300 miles. But now it's back. I did the sand-the-brake-surface trick, cleaned the pads and wiped down the brake surface with rubbing alcohol-all to no avail. Out of frustration, I took it to my new LBS to resolve. They just called and said even with new brake pads and a different wheel, the squeal is still there. That leads me to believe it's something else (yah, I'm pretty sharp, huh?). Any idea what could be causing this? It seems so strange that with different pads and wheel that it would continue. Thanks for any insights.

2012 Cannondale Quick 3 - BikePedia

Are the pads toed in?

The front edge of the pads should hit the rim first, by 2 mm or so...

I will confirm that, but I would HOPE the LBS mechanic would know that. He's a friend of mine and is a pretty sharp guy, but who knows, maybe he missed that. I'll double check.

I had Kool Stop pads on a bike, toed in, etc. and squealing would not stop. I switched to Cane Creek "Gray Matter" and all is silent. Plus full bike's worth in a pack less than around $12.

+1 this is the issue. Toe them in (you may have to tweak the brake slightly to do this) and no more squealing.

IME, Koolstop salmons tend to squeal more readily than some others. It sounds backasswards, but I've noticed the noise goes away after the rim gets a little dirty. Next time you ride, squirt a little water on the brakes then use them while they are still wet. Don't bend anything. Those are decent brakes and any toe issues can be resolved with the washers.

Thank you all. I appreciate the advice.