Milo of 409B made a video about virtual 4 bars for IQ. Here’s the link.
Great job, Milo, in describing how a 4 bar works and how to get the same result in another way! What you call the virtual 4 bar is also commonly known as a chain bar. I will be sending some of my new students to watch your video when they ask about 4 bars.
Good video!!! For what it’s worth, one of my team built just like that, but used a larger gear on one end. This gave them a slight tilt going up and made it easier to drop the rings off on the horizontal post. So it was still flat enough for the posts but the little tilt gave them a boost to get over the end cap.