Any detriment to hanging a bike by its front wheel? I came across the below image today and thought it a great idea for storing bikes. However I wasn't sure if literally hanging a bike by its front wheel might cause undue stress to either the wheel itself or the front forks. Has anyone else done this to no ill effect? In the image below the back wheels don't even seem to be touching the floor, which I would have thought would take some of the weight.
You'd have to calulate the actual forces to be 100% sure but it's not going to be a problem: forces on front wheel/fork/headset while e.g. just sitting on the bike, braking or landing jumps will be (much) higher than the force applied from hanging it.

That being said, I do note at least two problems with this setup: first, good luck getting one of the center bikes out without touching or getting stuck in another bike. Second: from the picture it seems like you'd have to hold the bike with one hand then use the other to attach it. Ok for a roadbike, but for anything heavier that is just hard. Usually these systems have an open 'C'-shaped fixed hook into which you simply hang the bike which is much more convenient.