My wife has shared my interest in road cycling since day one, so I suppose I'm lucky like that. However, we've both been into working-out for over 10 years, so we're pretty like-minded.
The one activity I couldn't get her into was mountain biking when we had to ride in mud - that lasted one ride and I caught holy-hell over that one the whole ride home
My pitch to her with road biking is that I'm going to be out riding for several hours, you can try to keep up on your mountain bike, but I'm not waiting up if you fall behind. So, want that new road bike now?
Works every time. Too bad the TT bike idea isn't flying with the higher cost of entry. Oh well, next season.