Key mechanisms relating to buffeting forces on tubes in fluidized beds have been identified by analyzing results from simultaneous measurement of force and pressure on a horizontal tube. Careful experiments have been carried out in a two-dimensional fluidized bed with an accurate sensor tube for single bubble passage, bubble chains and free-bubbling. It is shown that the buffeting force in fluidized beds consists of the net pressure force, i.e., form drag and lift, and additional forces induced by particles become so large for high-velocity free-bubbling beds that it is impossible to estimate the total force only from the net pressure force, while for low velocity beds the total force is mostly accounted for by the net pressure force. The wake particles play an important role for large bubbles, and therefore the details of this component have also been investigated for single bubbles as well as for bubbles undergoing splitting and coalescence.