What to look for when buying bicycles for children I have young children (5 - 7 years old), and having taught them to cycle on some really cheap bikes, I am looking to get them something more road worthy with a view to cycling to school with them. (~1 mile). 

I looked briefly at a chain store (Not my regular local bike shop but closer to home), but was disappointed by build quality - The bikes were about twice as heavy as my own racer, the bearings seemed a bit rough, and the final assembly seemed to have been performed by chimpanzees. Even if I bought these, I think they would require a lot of tweaking after purchase and a lot of maintainance.

What should I look for when buying children's bikes? Are there any check lists that anybody can recommend? With regard to weight, is it normal for them to be so heavy? Why are the tyres on children's bikes all so wide? (~2 inches across) - I would imagine that the lower weight of a child would make thinner tyres a better option?

Thank you.
To answer your specific questions first:


wrt weight: you are paying less for the children's bikes than for your own I hope? (they'll only fit on it for a few years after all) so kids' bikes use cheaper materials, cheaper usually means heavier in cycling gear. Don't expect to match your racer, but twice as much is a bit much even for a cheap model. Shop around a bit more.
Tires: Wider tires are more stable because of the wider surface and because the higher tire weight that comes with width increases gyroscopic stability of the tires. Width, and the thickness that comes with it means the tires can take more of a beating going over bumps, ridges, ledges and sidewalk edges. So actually wide/heavy tires save you time in money in patches both for your kids and for the tires.


As for things to look for:


Make sure the bike just barely fits your kid now (i.e buy maximum workable size), that way you can use the bike for a few years with just some adjustment to handlebar/saddle height.
Make sure you can add something like a flag on a long (high) pole to the bike. That way your kid is still visible from the other side of parked cars etc.
Brake quality is a big issue, especially if you are going out on the road with your kids, more so if the route is slightly hilly.
avoid bikes with gears unless you like spending your weekends cleaning and fixing bikes. Less gears=less maintenance.
Regarding the tire issue, and my point about bike size: when considering multiple bikes: get the bike with the largest tires. Larger tires=higher gyroscopic force=more stable and all at the same weight.
Don't overspend. Your kid is not going to be as careful with his/her bike as you are. You shouldn't be wincing every time they just let the bike fall to the ground where they stopped.