A motorized window treatment system may include a roller tube, a flexible material, a drive assembly, electrical wiring, and/or mounting brackets. A mounting bracket may include a channel configured to secure the roller tube in position along a longitudinal axis of the roller tube. A mounting bracket may include a base and an attachment member. The base may be configured to attach the mounting bracket to a structure. The attachment member may extend from the base and may be configured to receive an end of a roller tube. The mounting bracket may be configured to retain electrical wiring for powering a drive assembly within the roller tube. The mounting bracket may include a spring that is configured to retain the roller tube within the channel in the mounting bracket. The mounting bracket may include a sliding cover that is configured to cover an access opening of the channel.