The changes in the mean-square charge radius (relative to 209Bi), magnetic dipole, and electric quadrupole moments of 187;188;189;191Bi were measured using the in-source resonance-ionization spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in 187;188;189Big, manifested by a sharp radius increase for the ground state of 188Bi relative to the neighboring 187;189Big. A large isomer shift was also observed for 188Bim. Both effects happen at the same neutron number, N ¼ 105, where the shape staggering and a similar isomer shift were observed in the mercury isotopes. Experimental results are reproduced by mean-field calculations where the ground or isomeric states were identified by the blocked quasiparticle configuration compatible with the observed spin, parity, and magnetic moment.