Originally Posted by
zacharyt
I have another problem now though! The rear right post seems a little too large. Getting the right side caliper on is pretty difficult, and when I put the mounting bolt in the arm will barely rotate. I tried sanding the post down a little
...
Do I need to continue sanding down the post?
Are you sure the problem lies with the frame? I'd try all 4 brake arms on the post before trying to make the post skinnier. You don't want to mess up the post if the problem lies with the canti.