In regards to 1x12,14 and higher, the dropout spacing is going to get wider. And as far as gearing...I dunno, ride what works for you. Some people here don't need anymore than a single speed to get where they want to go. I've done my commute a number of times on a 42 pound 3 speed. Compact doubles also work quite well for me. If I lived in the mountains, I may want a triple instead. Anyway, ride what you want, and drink plenty of dubbels.