A variable speed belt comprising an elastomeric body, a tensile cord disposed within the elastomeric body and extending in an endless direction, a cog extending from the body, the cog comprising opposing flanks, each flank comprises a first planar surface describing an included angle (α), the first planar surface engageable with a sheave, each flank comprises a second planar surface disposed toward a cog tip describing an included angle (β); and included angle (α) is not equal to the included angle (β).