The 18-in frame is the only size in this range that ships with a kickstand, so a child can park the bike upright instead of laying it on the grass. It fits riders 47.2 in to 59.1 in tall, ages 4 to 8, on a seat rated to 132 lb, the sturdiest in the size range. Two training wheels bolt off when balance arrives. Squeeze the lever or back-pedal to stop. At 23.5 lb the frame stays light enough for a parent to load into a trunk after a long afternoon out.