Well I asked this question last year and ignorning all the nay sayers and after looking at the Suzuki, the Polaris and a few other (non-Chinese Quads) we then looked at the Yamaha 50cc (with electric start, I think it was the TTR50 not the Peewee50?) and the Honda CRF50. In the end Santa went with the CRF50, one for each girl as we picked two of them up in the pre-Christmas dealing time of the dealers for just slightly more than one Quad bike.
The girls are not even allowed to sit on their bikes without all their safety gear on. They were 6 and 5 when they got their bikes and could ride a pushbike without training wheels before we let them loose. The neighbor also lent us an electric scooter that used a twist throttle the same as the bike and we got them to ride around the cul-de-sac on that getting them to learn that there wasn't just one speed of flat out and also how to use brakes.
The girls can now ride their bikes (I won't let them in the back yard just yet as they WILL panic and go into the fence) and they have started to go over bumps and get all excited when wheels come off the ground! In Sydney they have been to Pacific Park and out to Leuwee. We are looking at getting them into fun-kana if they want to. They absolutely love it.
They have had many many offs but have never hurt themselves as we have the proper riding gear and also the throttle is restricted and we only allow them to go in second gear at this stage. During the day you can see them gain confidence then they have an off, and god bless their little cotton socks, they jump back on, but are much more weary than before. Then their confidence starts to rise again and they have another off. Good fun.
All I can say is have a serious think about two wheels rather than a quad. In the end actual price decided for us. You can wrap your kids in cotton wool and not allow them to do much and experience much in our nanny state. However my kids, whilst keeping them as safe as possible, will get to experience most things in a controlled manner and if they like it then we will keep going with it. Things like motor-bike riding, driving, water skiing, hiking, flying/aerobatics etc my kids have done and they love them all. Abseiling, rockclimbing, diving and shooting will be added to the list as soon as they can. Pity they have to go to school and I have to go to work! Nothing beats bonding with your kids as much as undertaking new activities. And these are all good wholesome, fun-for-the-whole-family things.
Just need to buy a farm or get access to a hundred acres or so closer to Western Sydney so I can get out more often to undertake these things with them!
Anyway don't listen to the naysayers. They are in ALL walks of life and in EVERYTHING we do. I do believe you should listen to all sides of the story though and as much as the good doctor here has been slightly bagged, I am sure he is well meaning. But in the end do what you think is right, most of us have a decent enough moral compass to know what is right and wrong. Let your kids experience life. There will be stumbles and if you have done your job responsibly then there will be no major issues. We learn for the stumbles, it grows our character but more importantly, that is how we learn. Yes the paint is wet...
Cheers
CB