I have a bronze anodized 700c Mavic Open 4 CD rim on the front of my recent Super Le Tour build that screams like a stuck pig when braking, in spite of having been scrupulously cleaned and with brand new Koolstop Salmon pads.

Ideas? I'm wondering if it is due to the anodized surface, or something else. The rear Mavic rim (different model) has a machined braking surface and is silent.

Brakes are the original 1985 DiaCompe sidepulls if that matters. Thanks!

With non-machined rims, you have to make sure you've got plenty of toe-in on those pads. One strategy that works for setting toe-in is to loop a rubber band around the rear of the pad to create a gap between it and the rim. Then set the front of the pad in toward the rim. This should fix it.

If it doesn't, the other thing that works is time. An extra clean rim is more prone to squealing in my experience.

+1 to the need to toe in the brake pads. If you can't do it with the Koolstops, you might spring for some adjustable ones from Velo-Orange: https://www.velo-orange.com/voadbrsh.html

Neal