I have a slightly shorter rear mudguard due to it having broken in the past and generally being a bodge job. The key point for it is leaning the bike on the rear rack onto the blocks of wood. This way the bike is supported on the back wheel, rear rack and front wheel leaning against the wall (has moment of pause because: Physics), which I feel is better than the bike pulling up on the wheels.
That said if the hook holds onto the wheels by the rim (not spokes) then half the weight on each rim should be okay as they must have at least that load with a rider on it (though compression not tension).
...
Anyway, I am less convinced by my ability to mount hooks into a wall that could hold 15kg without ripping out.
Yes, cunning use of a Useful Bit Of Wood™, there.
My take on dangling by the rim is that the bike frame isn't going to be bothered, but the rim might. I rebuilt the Streetmachine's rear wheel after a couple of years because it was cracking around the spoke nipples. No idea if that was train-related, or just too much spoke tension or what. The replacement has a much better rim with eyelets, which has some cosmetic scuffing but remains structurally sound.
My only other bike that's done dangling train journeys has similarly sturdy wheels, and has never had a problem.
Of course, if you're hanging it for storage, you can pad the hook with something soft, and it's not going to be swinging around like it would on a train, so much less load.
