Tall enough that you can touch the ground with the tips of your toes while sitting astride the bike and you have to be big and heavy enough to be able to control it.
As long as your feet reach the ground when you are sitting astride it should be okay. If you can only touch the ground on tiptoe then you are still too short.
As long as your feet reach the ground when you are sitting astride it should be okay. If you can only touch the ground on tiptoe then you are still too short.