A main shaft assembly of a wind turbine (10) includes a main shaft (34) secured to a bedplate (48) of the wind turbine (10) and a bearing (54, 58) seated within the bedplate(48). The bearing (54, 58) is held in place via a cover (68) that is secured to a mounting surface (49) of the bedplate. Moreover, the bearing (54, 58) includes an inner race (56, 64), an outer race (55, 62), a plurality of roller elements (57, 66) arranged therebetween. In addition, the bearing (54, 58) engages the main shaft (34) so as to provide rotation thereof. The main shaft assembly further includes a flexible member (72) arranged between the outer race of the bearing (54, 58) and the cover (68). As such, when the flexible member is compressed, a gap between the mounting surface of the bedplate (48) and the cover (68) is reduced or closed.