I know tons of people go SS or even fixed gear for commuting. I'm looking at getting a new bike and I'm not averse to giving SS a try (not fond of the idea of fixed at this point though) but I wanted to get the expert opinions on this. My commute is rather long. About 18 miles each way. Now, many days I can take the bus for about 13 of those, but some days the timing just doesn't work for me. Plus, I'd like to eventually eliminate the bus part once I get in good enough condition to do the full commute every day.

So, given my lengthy commute, is SS viable? I read somewhere a while back that the author didn't recommend SS for anything over 5 or 6 miles. The terrain isn't terrible - mostly flat - but I do shift quite often when I make the ride on my current bike (Surly Long Haul Trucker).