An axle of a scroll wheel for a mouse or other type of computer input device is held in a first part of a carriage. The first carriage part is joined to a second part of the carriage by a flexure. When a force is applied to one side of the scroll wheel, the first part of the carriage moves in one direction relative to the second part so as to engage a first switch. When a force is applied to the other side of the scroll wheel, the first part of the carriage moves in the opposite direction to engage a second switch. The carriage is connected to a base. When sufficient force is applied to the scroll wheel in the proper direction, at least a portion of the carriage moves and engages a third switch. The carriage includes a tang or other flexible member to bias the carriage against pivotal movement.