It's pretty obvious what riding high means here. No wonder it was called "The National Joy Smoke". And note the scientific precision of this thing. Of course the man must be behind. Note that although his seat is a little lower than hers, he's caught in a moment of pedaling which raises him above her, so that she has to look back and up to see him. Observe also that her coolots (shorts) allow for exactly the right amount of thigh to be seen.
Someone needs to talk more about the fact that so many Prince Albert and Sir Walter Raleigh ads of the 50s were focused on making the smoker more appealing to women. I suppose it was an easier sell than saying cigarettes made you more appealing to women.