A post-mountable exercise apparatus includes an exercise device, a 3-walled bracket and a bridge. The exercise apparatus is attachable to a post by surrounding the post with the 3-walled bracket and bridge, which tighten together in place on the post. The exercise device has a frame that supports a horizontal shaft rotatably mounted in the frame such that two crank arms extending outside the first side and the second side of the frame can be rotated to turn the horizontal shaft. A band tensioning device using a threaded member may be added so that tightening or loosening the threaded member causes a change in the tension of the pliant band and resistance of the exercise device to being rotated.