I'm posting here because I've browsed the SS sub-forum and there doesn't seem to be a lot of techincal information there so hopefully someone here can help me.

I am seriously interested in converting my bike to a Single-Speed. I've got semi-forward facing dropouts so my frame is designed to work as a SS. Part of my reasoning is curiosity about the feel and efficiency of a SS drivetrain, part is recapturing the nostalgia of childhood and a very simple bike and part is the fact that my bike riding is geared toward building or maintaining fitness and SS seems a good way to go.

I've been experimenting with riding in a single gear and not only is it doable, but I'm enjoying the experience. My research on SS's indicates that they are more efficient, for various reasons, and that a gear ratio of "x" on a derailleur bike will feel different (more difficult) than the same gear ratio on a SS. How big a difference is this? Are we talking a couple of gear-inches, 4-5 gear inches, or even 8-10 gear inches difference? I've been riding in a 61.5 gear-inch on my 3x9 drivetrain but what would the SS equivalent be? Would a 65 gear-inch SS feel the same? A 70? I checked the Surly CC SS and it has a 67.5 gear inch ratio so it seems I'm in the ballpark for what is common.

I guess my main question is when I find a gear on my 3x9 bike, how do I translate that to the same "feel" on a SS bike?