I think half the people posting on this list are a bunch of whiney old 'better than thous' who need to grow a serious sense of humour.
Yeap, if your SOLE intention in riding a corner is getting your knee down and you're using the street as your practicing place, then you're probably going to fuck up - and fucking up on the street is a very bad thing. No argument there...
But...
I've been riding for over 14 years and for 10 of those years I never even had a car, so I've ridden a LOT. I didn't 'learn' to get me knee down until I had a few close calls when I didn't 'THINK' I could make the turn. But I wasn't dragging anything, nothing slid, it was all in my head. I wasn't going too fast, I was surprised/misread a corner/a blind lesbian jumped out in the road swinging a 10ft dildo. Whatever. Spare me the 'every accident is avoidable' crap too - sometimes shit just happens and learning that you aren't limited to a certain turning radius can help you avoid a hazard better.
So, I took myself off to a deserted roundabout (on a road that wasn't open yet, so I could practice both ways) and went round and round in circles at about 30mph to find out how far the bike would lean, then how much faster hanging off and getting me knee down would take me.
LO! A miracle. I could go MUCH faster dragging my knee and peg, than just the peg. I could also drag my knee going SLOWER than when I was dragging my pegs. I therefore knew that I had quite a large margin left over if I was hanging off, even going slower than I would normally.
Getting your knee down on a blind-right on Highway 9 at 10am on a Sunday is pretty damn stupid. But getting you knee down EVER on the street being ALWAYS unsafe? Spare me! Ever ridden Mines Road at 8am on a Sunday? Visibility on some sections is MILES, especially the lefts at the end going toward Livermore. Ok, I know this is hard for you fuddy-duddies to take, maybe some people don't do it to pose, or to impress - maybe it's just FUN! Isn't that what biking is about? Or did it suddenly turn into a politically-correct friggin nightmare while I was napping? Did I miss the vote? Was it in Florida?
I've also got into the habit of hanging off when I have no intention of dragging my knee just because it gives me a larger envelope to play with in case anything goes wrong. And, if you do it ALL the time, you get to be pretty damn smooth. So I'd take umbrage with all these 'holier than thous' spouting on about 'I never lean off the bike except at the track, blah blah, it upset the bike, blah blah' - it upsets the bike because you're CRAP AT IT!
Maybe if you got down off your high horses and just practiced it all the time you'd do it as second nature. Even going slow, this gives you more cornering clearance ergo a bigger safety envelope.
And all the AFMers on here who I know could blow me into the weeds at the track, screw you - I can outride you on the street anytime - and by that I mean making smooth, safe progress without endangering myself or anyone else and not beating myself up over OMG I LEANT OVER 2 DEGREES TOO MUCH IN THAT CORNER TO BE SAFE! Shock horror. The street is changeable and learning to react and having an extra bit of ability left over is more ammo in your reserve for the unexpected. Yeah, you pick your places to practice wisely and there are MANY assholes out there who have no business trying to get there knee down yet, or even ever - but there are plenty of old farts like me and many others who pick and choose their places to do it and if the site of my dragging my knee on a deserted stretch of blacktop in the middle of BFE offends you, then please, use your neck muscles and turn the other way...