my ESP seems to be out of service today, so not knowing what is what, why dont you buy some 2X4s and some drywall screws and create something maybe something that wedges against the floor and the ceiling??
i once saw something for surfboards but i bet you could tweek it to work for ya, basically cut a 2x4 the same height of a wall either glue those little sample squares (or tack them) and wedge it between the floor and ceiling....
You can use this as a pattern for a four-bike vertical rack, substituting inexpensive hardware store hooks and 2x4s or 2x6s for the metal. The rack itself is 75" wide and 25" deep, although with bikes on it, it can be nearly twice that depth, depending on saddle height.
In my experience with only road bikes, I found I need only 16" between the hooks horizontally, but then I need 12" between them vertically. Although if you alternate hanging them front wheel, back wheel, front wheel, back wheel, you can move the hooks closer together both horizontally and vertically.
It'll hold up to 6 bikes. I've got 6 on mine;it takes up about 50x54"(the rack's footprint is smaller,but the wheels and bars stick out). If you only hung 2-4 bikes on it,it wouldn't be too big a deal to get them on off. Also has the advantage that you can easily move it if you redecorate or want it in another room.
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