Been trying to figure how much shorter a belt I need with my new upper pulley. Here's what I figured. Someone agree or shoot it to h#ll:
3 1/2 inch original upper - change to 2 1/2 inch upper

shorter by: 1/2 inch in height
plus 1/2 the difference in circumference (2 x r x pi)
which i figured to be around 1.57 inches

So I figure the belt needs to be shorter by a little over 2 inches.

Input???

Mark