Originally Posted by jeneralist

Different gears let you match how you're feeling to what the terrain is like. You can pick a gear that makes it so that you don't need to push down hard on the pedals -- as long as you're comfortable turning the pedals around more often. That trade-off -- how hard vs how fast -- will probably be something you want to change if the road has a hill in it, or if you're feeling more or less energetic some days. Three speeds may be perfect for you, especially if you'll be riding in a fairly flat area.