Referring to the above diagram , a 12″ wheel bicycle is the first bicycle which is recommended for the kids age between 2.5 -4. A 12″ bike is usually installed a pair of training wheel which helps to guide and train the kid on cycling. You may consider a tricycle as an alternate choice under this age group.
Between age group 4-7, a 16″ wheel bicycle is recommended. Most of the 16″ bikes is also come with a pair of training wheel.
When the kid reaches 6 year old, you may consider to select a 20″ bike for them. If the kid is still unable or lack of confidence to balance his/her body to cycle on 2 wheels, you may consider to install a pair of training wheel on the bike, but it is usually not so encouraged because kids at this stage are expected to cycle on 2 wheels.
The main difference between a normal 20″ bikes and a 20″BMX is BMX is built of strong frame and fork, using tough components will is suitable for rough rider. BMX bikes have no age boundary so long the rider ages 8 and above because it possesses a hige-raised handle and longer fram. If the rider is skillful on doing stunt and performance, a BMX is the best choice.
Another alternative choice for age group 8-13 is 24″mountain bike (MTB). MTB comes with multiple gear with a total speed of 15-24 . A MTB is recommended for teenagers who prepare to travel for longer journey.
A 26″ MTB is recommended for rider ages 13 and above.
If rider has interest on speed riding on road, a road bike or racing bike can be considered.
City bike is an utility bike is good for schooling or nearby shopping. Additional accessories such as basket, carrier and fenders are usually installed on this bike.