Comment by Tor3
That article is weird, for me at least. I very clearly remember when a bunch of kids around the age of six and seven learned to bike, all at the same time. All it took was a woman's bicycle, the old type (I should say "very old" type at this point. Big wheels too), easy for kids. The kids had to stand up, not sit (too big bicycle), and all it took was a single run with someone holding the seat, and letting go after a short while. That was it. No further training required. And that was indeed how I myself learned to bike as well, when I was a kid. Training wheels didn't exist, and are in my opinion pointless unless you want your three year old "bike". For older children it actively does harm.
> all it took was a single run with someone holding the seat
I think this is the key - holding the seat. The author of the article says "I did so in the usual manner - have her sit on the seat while I grab the handlebars and run along side her" - this surprised me, it would never occur to me to grab handlebars. I am not sure why exactly, it's an intuitive thing. As a lifelong road cyclist and an ex-racer, I have a pretty good feel for a bike... and you don't actually steer with handlebars, you "steer" (as in 'control where the bike is going') with your ass (which is why every experienced cyclist can easily turn with both hands off the handlebar). Someone grabbing your handlebars would misalign where your body is going vs where your front wheel is going and this makes you fall.
EDIT: I just realized that "steer with your ass" is something our coach used to say when we were kids. I think "your ass" is a kid-friendly proxy for "your center of mass".