My kids are 8 and 11. I take them for rides as often as they want to. The 11 year old doesn't like the big roads so we just ride where we can keep it under 20 ish.
My 8 year old like to go out on the "real" roads. He hasn't been on the freeway yet. There is no need for that. Both of them touch the foot pegs fine but my concern is if we go on a long easy ride oneof them might get a little sleepy. I make sure that we talk alot so I can keep track of this.
The kind of crap I did on a BMX bike when I was 8-11... and then I got a mini bike... I'm glad they like to go for rides.