When you hear that a bicycle has "ten" or "twenty-seven" gears, it sounds complicated. It really just means that there are plenty of gears and that you'll have an easy time pedaling your bike regardless of what the road or trail throws at you. Still, having all those gears is daunting. You wonder which to use and how often to shift. Well, to put your mind at rest and have you shifting like a pro in no time, we've prepared this easy guide.