I rarely head out for the sole purpose of clearing my mind, but I do find that cycling always relaxes me and makes me feel better. A couple of days ago, I was stressed to within an millimetre of having my neighbours on television talking about how I "always seemed so normal." I had planned a ride that day, and when I went out -- offroad with our 'cross bikes -- with my GF, I immediately started to feel better. By the time the ride was done, I felt great!