For the moment of inertia about an axis along one side of the triangle \( I_1 \), the distance of each particle from the axis is proportional to the side length of the triangle. For the moment of inertia about the perpendicular bisector \( I_2 \), the distance is based on the distance from the center of mass.
After calculating both moments of inertia, we find the ratio \( I_1 : I_2 = 3 : 2 \).
Thus, the correct answer is:
\[
\boxed{3 : 2}
\]