PS:
First motorcycle I had was at 5. An Indian sales sample with 12 inch wheels and exposed gear crank. Rode it alongside dad on his Harley Pan Head. I also drove cars and pickups at 5. Began mowing yards at 5. So, put the kids on the mowers and teach them not only how, teach them "why". My only learning problem was not how, where, when, but why. Teach them why it works. They're smarter than you think.
Another PS, just gave a mini bikes to my neighbors two boys. One is 4 the other is 3 and I'm ready to teach them to ride it. Their mom allowed them to have it, just isn't allowing them to ride it. I don't get that. lol
I did promise to build them a motor cycle stand treadmill for them to learn to ride on. She hasn't gotten back to me on that as of yet. It has only been 5 weeks though. lol.
Later all,
Max