I'm installing two of these bifold doors side-by-side in a 60" frame:
Unlike the closets that most people install bifold doors on, these will need to be opened and closed from both sides. From the traditional "front" side, I think I know where to place the knobs: on the hinge-side rail of the panel closest to the opening.
However, I'm not sure where to best place a knob on the other side. Opening is easy: push the door in the center. But closing flat, without a knob, is difficult. A knob directly opposite the "front" side knob would provide the right leverage, but it seems like that would prevent the doors from folding.