I only worry about the rides that if they fall out of they will do major bodily harm and you can't fall out of star tours! My son has been riding it since he was barely tall enough and loves it and he is a very small skinny kid. Personally I don't find it that rough, I mean you are sitting in a chair with a seat belt in a closed room. I think the barnstormer is much more jarring. This trip he just hit 48 inches and couldn't wait to ride RRC I was a bit apprehensive because he is 48 inches but only weighs 40 pounds but once he got the ok from the CM there was no stopping him, in fact he went on with my DD! Loved it didn't fall out and went on many more times.