7 is the magic age to ride by self so yes the 9 and 7 could ride togetherThis may not even be an issue come September. He's already improved leaps and bounds since he was younger. We never had this issue with the older two. Our #3 is just a curious adventurous and fearless little boy. He is learning, but I also want to take some precautions on my end, too. We will have lots of opportunities to "practice" over the summer and if need be, we will be putting him in a stroller for more than he would like.
I was misinformed. Somewhere else I read that kids 7 and up did not need a parent to ride alone. I wouldn't be sending them off to a park by themselves, I just meant on a specific ride where I would be waiting once they get off.