I moved into a small apartment last year and made custom wall mounts for my bikes. I have 2 that I keep inside - a CX bike and my tri bike. I went to Home Depot and got boards ~1 inch thick, pieces for metal piping (~1 foot long each), and foaming to wrap around the metal pipes where the bike frame sits. I stained the wood for appearance and drilled the piping on the wood so that the bikes would be held straight even though the top tube is angled. 3 long screws into the studs hold it solid. I attached a picture for reference!
They look fantastic and are very secure. Depending on studs, I could have probably fit 4 on the wall (2 on top, 2 on bottom)
Edit: I don’t know if the attachment worked… trying again.
Otherwise, I have a picture of it on my instagram:
https://www.instagram.com/p/BkOsvGqlpVj/