Trajectories of single air bubbles in simple shear flows of glycerol-water solution were measured to evaluate transverse lift force acting on single bubbles. Experiments were conducted under the conditions of -5.5 less than or equal to log(10) M less than or equal to -2.8, 1.39 less than or equal to Eo less than or equal to 5.74 and 0 less than or equal to \dV(L)/dy\ less than or equal to 8.3 s(-1), where M is the Morton number, Eo the Eotvos number and dV(L)/dy the velocity gradient of the shear flow. A net transverse lift coefficient C-T was evaluated by making use of all the measured trajectories and an equation of bubble motion. It was confirmed that C-T for small bubbles is a function of the bubble Reynolds number Re, whereas C-T for larger bubbles is well correlated with a modified Eotvos number Eo(d) which employs the maximum horizontal dimension of a deformed bubble as a characteristic length. An empirical correlation Of C-T was therefore summarized as a function of Re and Eo(d). The critical bubble diameter causing the radial void profile transition from wall peaking to core peaking in an air-water bubbly flow evaluated by the proposed CT correlation coincided with available experimental data.