In this paper we study a class of bimodal cubic polynomials satisfying two
critical points belong to one invariant Cantor set. These maps have generalized
Fibonacci combinatorics in terms of generalized renormalization on the twin
principal nest. It is proved that such maps possess `decay of geometry' in the
sense that the scaling factor of its twin principal nest decreases at least
exponentially fast. As an application, we prove that they have no Cantor
attractor