I like the "degree of exposure" element as part of a trail grading assessment. I like it a lot. But once again it's a variable that depends upon the skill and the foibles of the rider. For example, my "foible" is that I'm not too good with heights. This means that obstacles that I would categorise as "dead easy" suddenly become unpassable depending upon either how high up from the ground they are or how close to a very long drop they are. So riding along a foot wide plank on the ground is in the dead easy category. Take it six feet off the ground and I'm not doing it! It would have to be a six-foot wide plank before I'd go up there!
Another would be any trail only just wider than my bars, is once again in the dead easy category. But with a big drop to one side it becomes questionable. If its not too big a drop, I might get off and walk, but if the drop was big, then I would find it so unsettling that I would have to find another way around.
For those who are completely unphased by "working at height", fear of heights is a difficult concept to get your head around. It's irrational of course, but that is why it is so hard to deal with. I can't rationalise it, I can't argue with it, and just manning up doesn't work either. I just feel emotions ranging from uneasy to nausea inducing terror, depending upon the height involved and how long I'm exposed to it.
And the height exposure doesn't have to be real, it can be virtual!
When Thelma & Lousie went over the edge of the Grand Canyon in their open-topped car, I nearly threw up all over the carpet!
