How old should you be to ride a dirt bike does depend on the child. You may be surprised to learn that kids as young as 3 years old can ride small electric dirt bikes. Kids at the age of 4 are progressing to ride small petrol (Gas) dirt bikes safely. Perhaps with training wheels. Then kids aged 5-6 upwards are riding petrol (gas) 50cc dirt bikes without training wheels and even learning to take small jumps.