I bought one of the racks in the first post for my 4 mountain bikes (26 inch wheel through to 29er) , it works well.
It fits all (various widths from 2.1 to 2.4 inches) except one of my bikes tyres fine, the exception was my bike with 2.6 tyres , for this I had to use a car scissor jack to bend the rack bars apart slightly, now they’re pushed apart permanently the bike fits fine.
I alternate the direction the bikes are in the rack, ie back wheel in the rack for the first bike, then front wheel for the next etc, so the handle bars dont clash, and then you can roll the bikes in and out without issue.
It works fine with my road bike as well, but I typically keep that seperate.
I mounted the rack to a wall, so the bars that hold the wheel stickout from the wall rather than up from the floor as per the photo above, the bikes are more stable this way.