Originally Posted by: FingerSpasmOn the Circle of 4ths (I know this is also the circle of 5ths if you go clockwise.) I am trying to figure out why it goes C, F, Bb......why Bb and not B?

An interval of a 4th (fourth) is always a distance of 5 half steps. The distance from F up to B-flat is a 4th; the distance from F up to B is a tritone (or # 4th, or flat 5th).