Abstract: A modular archery bow riser which is machined to accept an adjustable wrist brace, adjustable thumb grip and finger caps. The forward surface of the riser includes a number of finger channels and accepts alternative finger caps having different finger grooving. An aft surface accepts a semi-circular bracket which supports a pivoting upright wrist brace arm. The position of the brace arm is determined with set screws fitted between a slot at the bracket and brace and between telescoping extensions of an alternative brace arm. A horizontal shelf mounts to a side wall of the riser and an adjustable vertical stop mounts to the shelf to support the thumb.