^I'll second that. Zacspins and Reverchon spinning mice are the only coasters I can think of where the forces make them too intense to be fun. Of course, there's loads of old knackers where 'rough' can be mistaken for 'intense' (Ultimate, Nash, Bandit etc.. ) but if we're talking about forcefulness alone then it's the spinny things that get me. Yuck!
Not a Zacspin but similar: Green Lantern at Magic Mountain in its opening year spun with a force and speed that was hard to believe. I mean, literally. When I was waiting in line, multiple groups kept looking up at it going and leaving. I found myself walking forward very quickly through the line (when does that happen? Not one group but many?). Then as for the actual ride, I could handle the insane spins, but the way that it flung me head first over the cliffs of the ride was kind of mentally/physically overwhelming, as if it were not something the brain was meant to handle. Soon afterward, the park modified the ride to make it spin less, and the main complaint from people shifted to the feeling of being banged up in awkward parts of the body.
Also, as other people have mentioned this type of ride, my first ride on X2 (when it was called X) felt overwhelming. I remember getting off thinking, but I love intense coasters; if I could barely handle this, how are people not having heart attacks on this ride? Now I’m a bit more used to it.
Still, these two coasters have always been my answer to this sort of question. I’m glad to see several others now saying the same kind of thing.