18.5
I'm measuring straight up with the tape from the peg and looking across and back to center of seat. I measure metal all day for a living and feal this measurement is accurate. I'm 6'1.5" and the ride is comfortable enough for me. I do believe the angle is better on GS than the r. I do have to say that when standing up my fingertips barely get to curl around the grips. I have to lean over a bit to off road ride in standing position comfortably. For my long legs there isn't quite a ninety degree angle which I hate but have to make do