Racers on this course undoubtedly have to know the layout comprehensively; what line to take on each of the 200 corners and every camber change. It is surreal listening to McGuinness walkthrough a lap of the course, with all the insane techniques and tricks which are added casually. The disparity between the sheer amount of talent and guts needed for an Isle of Man TT race and that of ANY other sport is severe. The only other sports I can think of that come close are free-climb mountaineering and maybe airplane racing.
"AEQUAM MEMENTO REBUS IN ARDUIS SERVARE MENTEM." -HORACE