Theres' really not a hard cutoff, as far as I can tell. It's more of a sliding scale, and the more that isn't current, the more "C&V" it is. Horizontal top tube? Lugged steel? Quill stem? Downtube levers or bar ends instead of brifters? Friction shifting?

But overall, we're a pretty welcoming group. So as long as you're not asking about a carbon fiber wonderbike with electronic shifting, we're probably open to discussing it.