Forget training wheels and other funky gadgets; all you need is a child who's ready to learn, a bike, a gently sloping grassy hill, and a wrench. You'll want a bike with a single gear and a foot brake that allows your child to stop by pedaling backwards, which requires less coordination than bikes with hand brakes and multiple gears. Make sure the bike isn't so big that he has to struggle to control it. Be sure to set the seat all the way at its lowest point so that your child is able to put both feet on the ground while comfortably straddling the bike.
Find a park with a grassy slope that's angled enough so the bike will coast down, but not so steep that it will be hard for your child to hold the bike still with his feet. There should be plenty of level ground at the bottom.
Start part way up the hill and put your child on the saddle with their feet on the ground, holding the handlebar straight and arms slightly bent. Be sure that the feet are lifted up while rolling to the bottom of the hill, and that the child is able to control the speed by putting his feet back on the ground, if needed. Walk the bike back up and repeat until your child can keep his feet on the pedals while coasting down. Once your child has more confidence, move higher on the hill and repeat a couple more times.
Instruct your child to apply the brake after the hill levels out. Once he is able to stop safely, work on steering with gentle turns to the left and right. Repeat riding down the hill, turning each direction at the bottom two or three times.
Adjust the seat so that when sitting on the saddle, your child is only able to touch the ground with his toes. Repeat.
Finally, raise the saddle high enough to allow a slight bend in your child's leg when the pedal is at the bottom of a stroke. Start partway up the hill and have him coast until he gets to the bottom of the hill and then have him pedal while riding circles in the level area. Allow a proud smile to cross your face because your child is now riding a bicycle!
Teaching your child to ride a bicycle shouldn't be hard to do. As a matter of fact it can be done in an afternoon or two. Teaching a child to ride a bike opens up a new world of freedom and fun to them. And it's great exercise, too!
***It's important to teach your child the importance of wearing a helmet at the same time you're teaching beginning cycling skills. Make sure the helmet is level when worn, not tilted back or angled to one side. The side straps should form a snug "V" under each ear and the chin strap should be cinched enough to allow you to slide only two fingers underneath. Make sure they know which is the rear and which is the front so they don't wear the helmet backwards, there's usually a sticker inside pointing in right direction. Most bike shops are more than willing to help fit a helmet correctly--you only have to ask.***