My large ring is trying to down shift about every 10 pedal strokes. The chain will start dropping to me middle ring but will shift back up to the large ring in about 1/4 pedal stroke. If I let the deraileur rub along the chain then the chain will not try to down shift. The small and middle ring don't try to auto shift.
Is this a sign of a worn chain ring? I checked the run out on the ring and the ring appears to be running straight. I am not a strong rider and if the frame is flexing I better start looking for a cracked frame.
If you have any ideas about what I can do to keep the chain on the large ring without having to let the deraileur drag, please let me know.