>>1608459from what I have seen they are farely good, aside from the rust eventually flaking the chrome off
I have seen a few that crack where they attach to the seat bolt.
but very few cracks where the they attach to the rear axle,
it does not stop the rack from working but it does weaken it a little, such that the bolts are holding it together
I have seen them used as a seat for a passenger, but I would not put much more than 20 kg on one