PedalingWalrus: Do You have a external or internal locking eccentric on your Rohloff tandem. I have a Burley Bongo tandem. It has the two grub screws with points that screw in from the outside. I have had to readjust many times. My Co-Motion Pangea Rohloff came with there internal locking eccentric. Because of my experience with my tandem I replaced it with the Bushnell clamshell type eccentric. The Bushnell expands out a larger contact area for better holding.