If they can walk, they can ride. Just make sure they got a good helmet and an appropriate sized machine. The tether is good, but do not forget that powerwheels make electric kiddie quads.. They are fast for electric, probably 5mph, but they are also usable indoors. Which i guess could be a bad thing (for the dog anyways! ) Major downside is no throttle or brake control, just a go button, you could probably rig something up to act as a throttle, but still no brakes and they do stop pretty quick without power.

 

I bought my 2-1/2 year old son a "powerwheel" (a different name brand I can't remember) for christmas and he loves it. You can lock the power at half speed or unlock it for half or full speed. In full speed on pavement I have to jog to keep up with it. It has big wheels on it so it has no problem getting thru the grass. I can't wait till it warms up!

 

Oh yeah, one more thing when you let off the pedal it automatically brakes and it has reverse too.

 

My son had his first electric quad when he was one year old. He couldn't even climb on it by himself. He could however stand in front of it, reach around and push the thumb throttle and run over himself. Like father, like son...then at 3yrs old we moved him up to the Power Wheels 12 volt quad for a year. At 4yrs old he got his first real quad, a 2000 Suzuki LT50. You would not believe how the experience on the battery quads helped him. He mastered the 50 in no time, so this past fall, we moved him up to the Suzuki LT80. He does great on it. We have already taken all the throttle limiters off, and he does good with the power.
I grew up with dirtbikes and couldn't wait to get my son on a dirtbike or quad. I wanted to start with the real thing, but my wife talked me into trying the battery powered ones first. She was right. This served as a great way to stair step him right on up to where he is now. The person that said that you will be sacrificing your riding time to teach your kid, nailed it right on the head. Also, I agree that you have to start them out wearing the equipment young....that way there are no bad habits to break later. I make mine wear everything, even in the heat of the summer....I don't care if it is just a short spin around the yard,no equipment...no riding!
One other thing that I have mentioned several times on this forumn before is the 2-way radios. I think these mounted in his helmet so I can coach him along the way, have helped tremendously with his developement as a rider and has given him a great deal of confidence. Also, I can fuss at him if he gets a little to wild. If you are interested in info on the radios, e-mail me.
ATV's in my family have been a wonderful thing. But they are not for everybody. You can't just turn them loose like on a bicycle. They can get hurt too easy. But if you take the time and coach them well....then they will have something to enjoy for the rest of their life....

 

exmxr,
My plan on training was exactly like yours, down to the radios. Great fun but I'll be coaching them the right way. The 5 & 7 year old can't wait to go riding.

 

I started out on a power wheels ATV for about 5
years and when I was 9 I got a Yamaha Breeze I had it for 2 years and now I have a 250EX (I'm 11) its good for me and my dad.