I've been on one of these in Denver. The spinning really isn't the most painful part of the ride - it's how tight they have to put the harnesses on. They're not adjustable; the machine just slaps it on seriously tighter than possible right over the bladder area so you won't fall out. It hurts so so so bad. Every time we spun around, people (in unison) would scream in pain.

I really liked it as a little kid though.