Originally Posted by Mr_Super_Socks
Since the crank length is the radius of the circle, and not the circumference, you are actually getting less of a % benefit than the straight percent increase in crank length.
i.e. pi (170^2) < 1.03(pi(175^2))
or less than 1% advantage.
The formula for a circumference of a circle is 2*pi*radius.
The radius is not squared, you're probably thinking of the formula for the area of a circle.
Leverage tracks in a 1:1 ratio with crank length.