Andrews, Lewis and Lovejoy introduced the partition function P D(n) as the number of partitions of n with designated summands. A bipartition of n is an ordered pair of partitions (π 1 , π 2) with the sum of all of the parts being n. In this paper, we introduce a generalized crank named the pd-crank for bipartitions with designated summands and give some inequalities for the pd-crank of bipartitions with designated summands modulo 2 and 3. We also define the pd-crank moments weighted by the parity of pd-cranks µ 2k,bd (−1, n) and show the positivity of (−1) n µ 2k,bd (−1, n). Let M bd (m, n) denote the number of bipartitions of n with designated summands with pd-crank m. We prove a monotonicity property of pd-cranks of bipartitions with designated summands and find that the sequence {M bd (m, n)} |m|≤n is unimodal for n = 1, 5, 7.