I've got the DVD version of Keith's old-school book. It's very good, and slightly humerous.
Countersteering is the most efficient way to make the bike lean over.
Once it's leaned over it turns because the front wheel is uneven on the surface (because of the fork rake) so it "falls flat" with the road and the wheel ends up turned in.
You only 'countersteer' to begin the turn, once the bike's actually turning it's not countering steering.
Obviously there's lots of other ways to make the bike lean all need to fight gyroscopic and/or traction forces so are inefficient. Gyroscopic force maintains a spinning objects position in space, since if you lean the bike over with only your body weight, the bike pivots around where the tyres touch the road, the spinning objects' (wheels, flywheel, engine, etc) position in space must be moved a lot (along the arc of the lean).
So, you counter-steer. Front wheel turns the other direction, so the bottom of the bike moves that way. The middle of the bike (where most gyroscopic forces are focused) doesn't want to move, so the bike ends up leaning.
It's easier to lean like this because the bike only needs to pivot around the center of the bike, and center most gyroscopic forces.
It's easy to rotate something that's spinning, but damn hard to actually move it.
And, it's even easier when you've got some gyroscopic force of your own (the now offset front wheel as it's counter-steering).
This is why children have so much trouble learning to ride bikes, and training wheels make it even worse.
The instant one of those training wheels touches the ground, the bike will turn like a car, as soon as the training wheel comes off the ground, it needs to counter-steer to lean and turn... that messes with kids' heads something chronic
Anyone teach a youngin' to ride a bike atm will find it heaps easier to get a bike that fits good, drop the seat right down and remove the pedals.
Let the kid push themselves around until the get the balance and can roll and turn propperly...
Then remind them about pedalling on the good 'ol 3 wheeler.
Then put the pedals back on and raise the seat a bit and it's a simple act of combining two already developed skills, which kids do easily.
Different on a moto though because of the weight, but trainers on the moto should only be there to catch the bike when they drop it. If they touch the ground during a turn it's just delaying the learning process.
Articles like those are pretty good, and Keith is awesome, but they rarely explain the whole thing coz they don't need to.
There's soooo much to bike physics it will blow your mind.
I've played with my fair share of nerdy RC bikes and robot bikes at uni. Sometimes it's hillarious the crashes that can happen.
Now someone just needs to bring up rear-wheel steering
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ZXR"900" - In pieces... again.
Another engine gone but at least the purple and pink are still there, oh yeah.
