I don't use a GoPro, I use a much lighter camera the Sony HDR-AZ1. If I wanted it for a GoPro, I would make the arm shorter by about 1". I have no problem with chip seal roads and camera shake. There are SHORT ARM versions included with the YouMagine files. The short arm version places the mount just over 1" away from the seat post when the camera is mounted in the upright orientation.

From the year and a half that I lived in Saint Claire Shores, I don't remember ever driving on a single smooth road in the entire state of Michigan.