General purpose bikes for kids between ages 2 and 10. Usually have one speed and coaster, foot brakes. Some have hand brakes. Also called dirt bikes. One speed, usually have hand brakes, short wheelbase frames, knobby tires.
More expensive models take MUCH harder use by larger riders better.
Best for riders age 10 or older, depending on strength and coordination. Made to withstand the wheel and frame stresses of ramp or half-pipe jumping. Have stronger, beefier wheel rims and hubs, larger, thicker bike frame tubes and front forks reinforced at stress points, heavier-duty seat posts, pedal cranks, etc. Some equipped with rotors and axle pegs for performing aerial freestyle stunts. A good bike for larger riders.