5 or 6 without training wheels. I rode my Big Wheel (remember those??!) earlier than that, I think. My dad taught me to ride by holding onto the back of the bike, running with me a bit, then letting go. I LOVED MY BIKE! Used to pretend that my Big Wheels was my "sports car" and my 2 wheel bike was my "station wagon" (like my mom's). I rode all the time until I was old enough to drive a car, and then I barely rode again until a year and a half ago. Now, I'm sad that I missed all those years...but grateful that I've rediscovered the joy of riding. Now, I'm trying to teach my 6 year old to ride without training wheels, to no avail. She's just not ready.