Bicycles for kids are sized differently than for adults. Adult bike sizes are determined by seat height and frame size. Children's bike sizes, on the other hand, are determined solely by the diameter of the wheel. Consider a few factors when purchasing a child's bicycle. The child should be able to get off the bike easily and straddle the bar with both feet flat on the ground. Not only should the child be able to get off the bike easily, but onto the bike as well. Leaning the bicycle slightly should allow the child to sit on the seat and to pedal off. The less expensive bikes will be heavier due to the material used in the frame. A reputable local bike shop will be able to assist in the purchase of a bike offering information on safety and fit.
12-inch Wheel Diameter
A bike with a 12-inch wheel diameter fits ages 2 to 4. Measure the child's inseam (from the top of the inside thigh to the ground) to see if it fits the recommended inseam of 14 to 17 inches. Most bikes in this category come with training wheels.
14-inch Wheel Diameter
A bike with a 14-inch wheel diameter fits ages 4 to 6 with an inseam recommendation of 16 to 20 inches. Note that this size is not readily available and difficult to find.
16-inch Wheel Diameter
A bike with a 16-inch wheel diameter fits children ages 5 to 8 years old. The recommended inseam for this size is 18 to 22 inches. Rear coaster brakes are typical on this size of bike; however some will have front hand brakes.
18-inch Wheel Diameter
A bike with an 18-inch wheel diameter fits children between the ages of 6 and 8 who have an inseam of 20 to 24 inches. This bike size is not readily available.
20-inch Wheel Diameter
A bike with a 20-inch wheel diameter fits children ages 7 to 10 years old. The recommended inseam for this bike size is 22 to 25 inches. Some of the bikes this size have gears and hand brakes.
24-inch Wheel Diameter
A bike with a 24-inch wheel diameter is appropriate for ages 9 and up. The inseam recommendation for this size is 24 to 28 inches. At 24 inches, these bikes can sport most of the same features found on an adult bicycle.