Anyone have experience and suggestion as to what is the "standard" chainring, sprocket ratio to use. I would imagine that it would also be a matter of terrain and personal preference but I'm looking for a starting place or range.

Also, anyone converted a 9 speed to a single? I have a frame that I love but I'm tired of having all those useless gears hanging around. Possible, practical, pitfalls? Thanks for any info or insights.