All Sunday frames use a mid bottom bracket and an integrated headset. A BB shell starts off perfectly round before the frame is welded, but after welding the shape is distorted due to the weld heat. No longer is it perfectly round, which makes it more difficult to install your BB bearing. It is difficult to install a round bearing into something that is not perfectly round. We go back in after-welding to remachine the BB and headtube, so that they are perfectly round and your bearings fit in without any issues. Very few companies take the time to do this.