WHO ARE THEY FOR? - These are for seven to ten year olds who want to ride from A to B with both wheels on the ground. If riding without parents, riding only short distances, or if hooning around is the main purpose for the bike, a freewheeling BMX could be a better choice.
WHAT TO LOOK FOR
Gears - They'll have fifteen, eighteen or rwenty one gears, supplied by conbining five, six or seven sprockets at the back with three sprockets up front. More gears means smaller jumps between gears. Eighteen and twenty one speed gears will give better and smoother shifting than fifteen speed. A sinsible choice in this size is a bike with only rear gears (a single gear lever and five, six or seven gears), but they're about as rare and hsn't teeth in Australia at present.
Gear Levers - Small hands cope well with twist grip style gear levers. Also, thumbshifters are simple and reliable, and generally not too difficult for riders of this size to use.
Brakes - Mose will come with V-brakes. These are pwerful, giving plently of stopping power.
Brake Levers - Make sure the brake lever reach is OK, so the rider can comfortably reach and operate the brake levers. Many brake levers have adjustable reach. Adjusting the lever reach will mean readjusting the brakes. It's difficult to adjust brakes to a very short reach lever; slight brake rub on the wheels can be diffucult to avoid.
Weight - All else being equal, a lighter bike will be faster, easier and more injoyable to ride than a heavier bike.
Tyres - If the bike will mostly be in the dirt, a knobbly wide tyre will be good. If it'll usually be on sealed roads, consider a narrower, smoother tread tyre. If the bike doesn't have suitable tyres fitted, don't worry, they can easily be changed.
Bike Size - The rider not only needs to be able to stand comfortably over the frame with feet flat on the ground, they also need to be able to steer fcomfortably while seated. Check this before buying.
Alloy Rims - Alloy rims don't rust, and brakes work reasonably well in the wet on alloy rims. Steel rims rust, and give hopeless braking performance when wet.