I don't have any issues regarding Chris K's formation and (and definition) of the CR category. I won't be riding the event anyway, since I have nowhere near the required mojo for it.
But as a point of clarification, I believe a 7-cog Dura Ace EX cluster was available in 1982.
Dave Ross Portola Valley, California USA where I haven't seen so much "testing of the rules" behavior since my daughters went away to college!
Tom Harriman wrote:
"Sorry Mitch. 7 Speeds didn't show up until the 1990's, and had a rather short life. The 8's were showing up in the late 90's. But for this list, we'll have to wait for 2023 to discuss it."