This shows the steel Shad bracket attachment more clearly.
GR,
Your photos show the Shad attachment plate. It obviously does not load the FJR rear rack...but deposits the load to the FJR rear subframe.
I agree, that is a great picture of the Shad mounting rack, and clearly shows what is going on. But I disagree with the idea that there is no loading of the stock plastic luggage "rack". Yes, the rear center mounting bolt does transfer load directly down to the bike's subframe (the GIVI works this way too), but look at the forward part of that bracket. It clamps directly to the forward horizontal member of the plastic rack. So the plastic rack is bearing the weight of the trunk in the front.
We've already seen from wfooshie's marked up diagram that the entire case is seriously cantilevered off the rear end of the bike. That means that the solid center bolt mount will act as a fulcrum and we will be prying the Shad's steel plate bracket against the plastic rack.
The racks have two vertical pieces at the front edge that also go down through the rear cowling to the subframe to support the front end of the rack.
Here's what we're looking at on a Givi:
Both the stock plastic rack and the Givi steel frame fasten at these same 3 rearmost points of the subframe. These three points support the entire load onto the rear cast alloy subframe.
Here' a pic of where the two vertical elements fasten to that subframe.
So, all the weight of the trunk and its contents will be cantelevered on this subframe and this is what ends up eventually cracking if overloaded, usually just to the side of that red button. THat button is just a means to turn off my bright Whelen LED 3rd brake light. I've actually never needed to use it.
Now this is where the GIVI Is different.
The Givi rack also replaces the two passenger grab handles, which become long, relatively stiff levers against the cantilevered forces on the subframe. In essence, those handles are struts resisting the sub-frame from flexing under load. The stock plastic grab handles aren't stiff enough to prevent the subframe from flexing and cracking.
Now, in all fairness, there is a sticker on the GIVI rack stating that its maximum load capacity is 13 lbs, which would one would think would have to include the weight of the trunk itself. My empty V46 trunk weighs 10 lbs. :huh: Obviously that doesn't give you much headroom for dropping a case of frosty cold beers in there. But I'm pretty sure that is just a CYA sticker to limit Givi's liability. And, FWIW, the stock plastic rack (rear carrier) is only rated for
7 lbs. on first gens,
9 lbs on 2nd gens, so you do the math.
