How Bed Stiffeners Work

I have a set of Heavy Metal Off-road bed bars and am curious what exactly bed stiffeners do vs cross bracing along the bed rails. These bars are very heavy duty, they are 1.75” tubing and should tie the top of the bed along the bed rails together and prevent any substantial deflection of the top of the bed. Are bed stiffeners intended to prevent the bed sides from deflecting inward/outward or prevent buckling/bowing outward (see dotted line on my rough sketch). I could see a less robust bed rack or a shell allowing deflection in the direction of the arrows on the sketch (out or in) but with these heavy duty bed bars I can’t see the angle bracket of the stiffener in one location doing much more than the bed bars themselves. I may still get a set anyway for piece of mind and for the extra tie down points I would just like to understand what problem the stiffeners are intended to prevent.

 

There’s a video on YouTube that demonstrates it but basically the main job isn’t to keep the bed from further spreading which the stiffeners aid in that but the bottom corner where the bed stiffners sit on top of crack since it’s plastic when it has lateral force (off roading etc) so the main job of the stiffeners is to prevent the cracks in that location

 

there's a metal seam right at the 'crotch' at the rear bottom corner of the bed, where the two metal sections meet. the metal upright that later connects to the composite bed, as well as the metal tube that runs across the width of the truck and connects to each side.

this picture is straight off total chaos' site, credited to a post from this forum:



while you're correct that your bars are heavier duty than most, the issue has more to do with use and weight. even with your bed bars, the two rear-most sides will flex with a heavy upper load, but will likely flex in parallel with each other, but still against the underlying frame, because the bed frame isn't designed for that significant of an overhead load.

any bed stiffener is going to add material to the above weak corner, which works to increase the bedside load carrying capacity, which will reduce the potential metal flexing.

 

Total Chaos stiffeners, $175. Bed bars, far more than $175. Repairing cracks in the bed AFTER the parallel motion cracks it, more than $175.

Does that math help?

 

I should also state, I don't need the stiffener aspect at all, but installed them on my truck specifically for the added rear tie downs.

If you're actually using your truck for camping and the like(that I'm not), this is even more of a benefit to installation than the reinforcement acspect