riding a shared paved trail last week I saw a Dad w his son who was learning to ride. they reminded me of me & my kids. Dad had him suited up with gloves, knee pads & helmet. anyway, from a distance, I spotted them but then heard a thud. I looked up just after he had fallen & hit his forehead on the ground. he was on his hands & knees lifting his head. it was loud enough for me to hear from a closing distance. as I rode by I said "wow that was a good one! good thing you had you had a helmet on!" & tapped my own helmet as I passed with a smile. Dad smiled but the boy looked a little embarrassed. he'll do fine. regarding speed, I don't think he was even rolling when he fell