I have a Wunderlich tank ring version. The ring came off my 1250RT and fits the 1300. On the GSA, it needs 2 washers on top of each of the provided spacers on the tank ring, to clear those ugly BMW tank bag brackets. If you reverse the lock mechanism under the Wunderlich bag (4 screws), the bag then sits further rearward and doesn't interfere with the phone cubby.