15 years
It depends if you want a street bike or an offroad bike. There is no age limit for riding offroad, but to ride on the street, you must be at least sixteen.
there are no age limits for dirt bike. but there are recomendations for size
18
no certain age to own and ride but there is an age limit to buy
yes you can
till your big enough to fit in someones pocket
im 16 and i went down the hill and back on the sidewalk real fast and i got a ticket... and i got my permit
Im not sure of the street legal knowledge of of scooters in California but I know on sidewalks and bike lanes you cant. the age limit is 17 +. hope that helps. this site will have even better knowledge (and great deals on scooters) . just pick your state and it will have what you need. http://www.thescootermall.com/StateLaws.HTML
Its more about your riding ability than a set age. If you can physically handle the bike and have confidence with it, go for it.
13
18
Seven