In regards to the bike hanger did something along the same lines this weekend using some cheap tool hooks, i think the two arms of those are much closer together than your idea. Managed to hang up a road bike and a couple of mountain bikes no problem with brakes etc. As also mentioned there is the option of hanging a few bikes using the wheel hooks in between. So not a bad idea at all, although i am tight and it was in the garage so the hangers would probably be too expensive for me!
In regards to the bike hanger did something along the same lines this weekend using some cheap tool hooks, i think the two arms of those are much closer together than your idea. Managed to hang up a road bike and a couple of mountain bikes no problem with brakes etc. As also mentioned there is the option of hanging a few bikes using the wheel hooks in between. So not a bad idea at all, although i am tight and it was in the garage so the hangers would probably be too expensive for me!