A guy on the Adventure Rider Forum recently lost his Top-Box off his Stelvio, complete with a nice Sony Camera, a couple of Lenses, and various other bits and bobs.
His Rack Rails snapped at the rear Bolt Holes.
This is the Bar of another Stelvio, from my FB Stelvio/V85 owners Group.
Luckily he noticed the Top-Box sagging before the other side broke completly.
As you can see, once the 8.5mm hole is drilled through for the Bolt, and the top end is counter-bored for the Head, there’s very little metal left.
Bar is 18mm square Steel.
The Bolt/Hole is right at the point where the stress on the Bar is concentrated too.
Poor design all round really.
I made replacement Bars for mine, out of 30x30mm Box-Section Steel, 3mm wall thickness.
The slots in the Mounting are only 23mm wide at the base (they taper outwards to the top), so I had to Mill them out to accept the larger Rails.
If you have a Stelvio (other models may have similar Rails?), and use a Top-Box, and/or regularly carry heavy items, it would be worth checking the Rails.