The problem with children's bikes is that kids outgrow bikes as fast as they outgrow clothes. The 21-gear Morph looks like a mountain bike, but its unique features are its extremely long seat post and hinged frame, which enable the bike to grow along with your child. Experts say the Giant Morph is good for kids ages 10 to 13 with an inseam of 26 or greater. On the books, kids' bike sizes are recorded based on wheel size, but frame design plays a big part in the fit of a bike. This is why the Trek Mountain Cat 60 and the Schwinn Aerostar suit different inseam sizes - even though they have the same wheel size, one has a mountain bike frame and the other a BMX frame.
Kids seem to be happy with fewer gears than adults.
Although some advanced mountain bikes with 21 gears are marketed to children, the typical kid's mountain bike has six gears. BMX models have no gears. It seems that shocks are rarely discussed in the world of kids' bikes, probably because suspension systems are too expensive and too sophisticated. Kids' bodies absorb shocks a lot better than adults, anyway. Graphics and colors .