Originally Posted by
PeteHski
I agree, not that much difference, but I wonder if the 50/34 was chosen to be at the limit of what was considered to be a smooth shift? Otherwise why would they have not chosen a wider range with less gear overlap?
True. But Shimano is famous for system robustness and tolerance; Very often their rear derailleurs can accommodate a bit more compacity than their rating.
Also, others on here have done 20T drops for touring bikes back in the day of flat chainrings with no shift ramps or pins. But, upshifts may not have been as smooth.