Step 32: The World's Best Bicycle Storage System
They hang by hooking their seats over a horizontal pipe so they hang just overhead.
If they don't have seats you can use a loop of rope or poke them over the end of the pipe.
We used to hang them over one of the water pipes, but the safety office didn't like that. So I used tapcon masonry screws to bolt a length of unistrut to the ceiling, and used chain to hang a different pipe from that.
This method gets them off the floor and out of the way, and lets you hang any number of bikes in a small space. It doesn't bend the wheels etc. etc. Assign your students to list all the marvelous ways this simple pipe is the greatest bike storage system in history.