You don't NEED to do it at all. I never hang the knee out on the road because there's no benefit. You can get the correct body position without sticking it out at all. On the track where lean angles are present to the degree that one's knee would touch the ground anyway--then it becomes something one can do to gauge, hold the bike up, and the like. I have never seen an instance or experienced one where it provided a "pivot point" due to wind resistance.

 

From my understanding, when you are monkey hanging off the bike and knee dragging, you decrease the necessary lean angle of the bike to accomplish the turn

 

raylee

 

What you hardly need to knee down on public roads, if you do; either your going to fast! or your being an idiot throwing your body half ways off the bike taking a turn at 40 just so you can get your knee down. I always thought it was for measuring how much more you can lean the bike down before lowsiding it, well atleast that's what i thought.

 

Well I think I put or may I have put some myths out the door. Idk. At first I thought it would help to "throw" out my knee. After I processed that thought I thought that was just dumb and dangerous! I'm very skeptical of getting hurt doing anything. So any time I come in to any corner I always keep my inside knee pressed to the tank and countersteer thru the corner while keeping my eyesight directed towards exiting the corning. On a harder corner I will shift my body towards the inside of the bike maybe an inch or two bc I found for me that's all I need. This is all on the road and on our long back road rides. I haven't been on the track yet

 

Some riders lean using their knee against the tanks, some swing their knee out which allows your foot heel to appl pressure to the pegs......the greater your knee is swung outwards, the more pressure applied, the greater the lean.

Or it can be as simple as habit...

 

It's all about getting your body on the inside of the bike. Not just your ***. Not just your head. Your entire body. The knee is used to gauge your lean angle. Also to get you off the bike. If you stick your knee to the tank, you will stick yourself to the tank. You should have almost all your weight on that inside peg with maybe your outside leg holding you... Do not reach for the ground, you will strain your body position...don't worry, you will reach it eventually.

I find it especially helps corner exits.. the bike wants to stand up as you give it throttle..getting more weight over the inside part of the tire will help keep the bike there.

The rumor about using a knee to keep the bike up I believe is related to riding hard in the rain in which case they WILL actually use their knee to keep the bike from lowsiding.

Looking THROUGH a turn, countersteering, and using smooth throttle and brake inputs are the first part of getting quick on a bike. Lines are important too as is body position.

Dont get too used to not looking THROUGH a turn because if you focus on the exit, one day you will find yourself in the grass or going right into someone else.

Weighting the peg and kissing the mirror are all ways just to get you to hang off the bike. At lower speeds, it's easier to achieve steeper angles and thus you don't need to get off the bike as much as you get faster which is why the fast guys are basically ground/knee/bike. But notice even the GP guys will hang off like crazy on the faster stuff.

High speed MotoGP cornering at 1000fps - Casey Stoner - Red Bull Moments - YouTube

 

1. It lets the bike lean less for a given speed. By sliding off the
inside of the seat, your body weight is moved towards the
inside of the corner. This means the bike needs less lean for a given
speed and turn radius. As ground clearance is often the limiting
factor in cornering (particularly at higher speed) this allows you to corner at higher speeds.

Here's some nerd info that describes turning geometry:

t= arctan [ v^2/(g*R) ]

v is your velocity, R is the radius of your turn, g is the
gravitational constant. t is the "lean angle." It's the angle between the horizontal, and a line from the contact patch of your tires through the center of gravity of the bike/rider whole.

Hanging off and sticking out your knee moves the CG of the system to
the inside, while leaving the bike more upright, so you don't run out
of ground clearance.

Aside from running out of ground clearance, a second limiting effect
is caused by excessive lean. At lean angles below 45 degrees from the
horizontal, tires no longer purely roll and are rotating more about a
vertical axis rather than a horizontal one. This makes them act more
like a rotary brush of a street sweeper than a rolling wheel. With
steep lean, the contact patch twists in place scrubbing away traction and power so that leaning farther reduces cornering ability and ultimately causes a washout in the turn.

2. Some people like to 'feel' the road so they know their lean angle.
(You can't afford to look down for obvious reasons).

3. To use your knee to change the balance of the bike, for
example taking some of the weight off the rear wheel when you want to
induce a bit more slip.

4. Some will claim it also aids braking (because of air drag) going into
a corner. Every little bit helps....

5. Virtually no reason at all to ever need to do it outside of race track conditions.

 

The real question is why would you drag your elbow like Stoner in the video above?? does that help help with lean angle or wind? I would hang my knee out really far on a corner to improve the position of my coin purse.

 

Madman already explained it. Its not about knees or elbows, its about body positioning. Stoner hangs so far off the bike that his knees and elbows touch the ground. Some use it to gauge, some its habit, but what matters is body position.