Extension for BackPower towbar-mounted bike carrier, 4th bike

To expand the capacity to four bicycles, an extended rail holder is attached to the bike rack. Both the third and fourth wheel rails are then screwed onto this holder. The third bicycle is secured to the frame as before with a single support arm, while the fourth bicycle is attached to the third bicycle with a double support arm spanning from frame to frame. This extension increases the weight of the rack by 4 kg.