Some children want a bike that looks just like an adult version - and if they're aspiring to look like an adult mountain biker, things can get tricky. It's common to see children's bikes with suspension forks, but most manufacturers of the best kids' bikes don't provide this until children are at least eight years old.
This is because a young child's upper body mass is low and they're rarely able to get the most from even finely tuned, responsive forks - and suspension will always add to the overall weight of the bike.
When it comes to gears - these should be introduced gradually. Most of the best kid's bike brands opt for single chainrings, with a wide spread at the rear cassette. For learners, this makes the whole process easier - and for older children, even those on racing road bikes, the single chainring helps to keep the weight down.