Now that I've been teaching cycling 5+ times a week my legs feel pretty close to a perpetual state of soreness. I crave the days when I'm not teaching so I can give them a rest, yesterday was one of those days, today was not. I've heard from several people about using a foam roller is to stretch sore muscles, but I've only given it a half-hearted try once, using one at the gym. They look like such a simple tool and the "exercises" appear to be so basic that it doesn't seem like they will be very effective. They're not expensive, but on a graduate student budget even $15-$20 is a major purchase. Has anyone had experience with a foam roller? What kind of success have you had? What stretches have you done? What's the difference between an 18" and 24" roller (besides the obvious 6 inches)?