Actually, after thinking about it, it would work for me.. The biggest problem I have run into is chainring sizes, a 35 would be a good one. As long as I maintain the 2:1 plus an odd number gear I'm ok. 16+16=32, 39-32=7, or 18+18=36, 39-36=3. If I was looking for a big gear using the rule of four, I could do a 39/12, which would give me 2:1 plus 11!!! almost 3:1! Or I could go 39/20, which I think would be waaaay to easy. I had a 28/14 while I was doing fixed gear, and spinning that sucker was tough!! I have one hill during my commute though, and it barley makes the cut as a hill.