adaml wrote:How do they compare in the speed stakes (single vs. geared)?.......I'd be willing to lose a few km/h on average, but not much. My commutes are fairly flat (inner Melbourne) so my gear ratio would reflect this.
There is more pedaling efficiency per stroke on a SS so if you are reasonably strong in the legs and riding on flat terrain you will find there is no real differnce with the right ratios. You can accelerate a bit snappier and the extra weight loss from the lack of drivetrain makes this easier also. I raced/rode geared bikes all my life and made the switch to SS a few years back for something different but I'm totally converted now. I can now keep up with my geared XC mates on a SS MTB....probably due to an increase in fitness from not relying on gears.
It also makes one focus a bit more on pedaling rhythm and leg strength, which wont hurt your speed at all