An adjustable backrest support provides a seat back angle adjustment that eases the task of adjusting the position of a wheelchair backrest while keeping the user seated in their wheelchair. In one embodiment, the adjustable backrest support includes a strut, an adjuster ring, an adjusting barrel nut, an angle adjuster, and a clamping system including a clamp. The clamp may include clamping screws that permit adjustment of the seat back reclining angle the angle or the seat back lateral position when loosened.