No there is not anything holding them down. However, in order to place them in there you have to install them at an angle, they don’t drop right in. And as such will not fly out, but they could move. That being said, having them basically strapped together with the skis, it is pretty secure.Love seeing these DIY's, nice work! Are the 2x4's held down by anything, or are they 'free-floating'? I see your bedcover, so probably not an issue for you, but if someone doesn't have a cover, how will it work?