My kids first rode Space at Disneyland when they were 5,7, and 8. I'm afraid I didn't prep them (or my DH!) very well.The 5 and 7 yo were terrified, the 8 year old didn't want to ride it again that trip and my DH has yet to ride it again to this day.
at 4 years old my kids were daredevils. I also did not prep my kids to what to expect, darkness and in a seat all alone.
Let me tell you, I had topry his little fingers off the bar and he didnt talk for at least a few hours afterwards.
Now its my GDs turn and we show her youtube stuff and she is on the fence at this time