An exemplary seat having seat connection mechanism for attaching the seat to a wheelchair includes a seat frame and a backrest. The backrest is pivotably connected to the seat frame through a pivoting mechanism. The seat further includes a biasing member connected to the backrest at a first connection point and a second connection point near the seat frame. The second connection point and the pivoting mechanism are spaced apart from one another by a distance C. The seat further includes an adjustment mechanism adapted for changing the distance C. The second connection point may be connected to a guide arm, such that the position of the second connection point is adjustable by sliding the second connection point along the guide arm, thus making the distance C adjustable.