You CAN be detained for not having ID, until they know who you are, then they will release you unless they have another reason to hold you. You CAN be ticketed, just like a motor vehicle operator, in most states. It doesn't matter that you don't NEED to carry ID to ride a bike, nor does it matter that you are too young to have a valid ID. If you do something in violation of the rules of the road for the state or city/town you are riding in, the police have the right (and responsibility) to pull you over and cite you for that violation. If they ask for ID, and you have it, you must turn it over to them. If you don't have any, they can take your word for who you are, or detain you until you prove who you are. Personally, I never go anywhere without ID. I wear a road ID tag on my watchband with name, address, phone, wife's phone, and blood type/allergies. Just in case!!!