15½ Youngster up to 75 lbs

16.½ Petite Between 65 -125 lbs

17.½ Adult Between 125-235 lbs

18.½ Large Adult 235-280 lbs

19.½ Extra Large  280 & up

A smaller person can ride the larger seat, but a larger person cannot ride the smaller seat.

A child can comfortably ride a adult size.