Yes...i think I everyone has it right..riding prepares you for riding. If you need to develop your overall aerobic fitness before you go on (your) tour or (any) tour that involves long climbs such as the Cascades or Sierra, you might want to use stairmaster machines or the more recent, lower impact aerobic training machines that many gyms have.
I am rather old fashioned and trained for my world tour (and other, summer tours) by running stair laps in the winter months. It is powerful exercise that build immense lung/oxygen capacity which comes in handy when you are on the 15th mile of a 30 mile climb!
But stair laps have fallen out of favor since they can be brutal on the knees and other joints.
roughstuff