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Body Positioning (hanging Off)


CHAOS
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After looking at tons of different pictures and researching this topic on several forums...I have come to 0 conclusions on which BP/form is "better".

 

I have read and heard all of the information regarding hanging off the bike to keep it more upright and lower the center of gravity.

 

I have seen tons of pictures with people hanging off the bike...and tons of pictures with people basically inline with the gas tank. Some people are off the bike and "kissing the mirror" where some people are not.

 

Ok, this first picture is me. I am in the middle (all black). This picture was taken at Talladega GP.

 

I am off the bike, butt and upper body. It also looks as if the instructors have close to the same BP as I do.

 

070923-7463.jpg

 

 

 

This picture is of a professional race. You can see how his body is basically inline with the tank.

 

mat1.jpg

 

 

Here is another example of a rider not hanging off. (Yes - that is a Hayabusa). Maybe this isnt a good example because you can see his bike has alot of lean angle.

 

busaroadrace.jpg

 

 

Here is an example of both styles.

 

0007.jpg

 

Here is another example of a racer who is "biased" to the inside but is basically inline with the bike. .

 

02sugoce02800cx8.jpg

 

More examples of the two different styles...

 

JB202.jpg

 

MMS_9541.jpg

 

Ok, I know that the most common response is "just do what works for you". But scientifically speaking, there has to be one way that is better than the other.

 

There is a distinct difference between the pictures of riders who are inline with the bike and the riders who are hanging off (like I am in the first picture).

 

I read a couple of discussions stating that hanging off the bike the way I am and some others are can be detrimental because you can actually "pull the bike down". They said that by staying a little more inline with the bike you are applying more downward force on the tires, spreading the load and utilizing more of the middle of the tires instead of loading the sides of them.

 

So which way is better?

 

Is my BP in the first picture ok...or should I be a little more on top of the bike?

 

(Sorry for all the pictures, I couldn't really explain myself without showing examples).

 

Thanks Chris

 

BTW, I am signed up for Level III at Barber in August so maybe we can continue this discussion in person......

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Here is another example. Nicky is straight up and down with the bike...he isn't hanging off at all. His bike and obviously his tires are different than mine.

 

Is that the major difference? If your tires are good for 60+ degrees of lean angle do you not have to get off the bike as much...and you can simply lean over?

 

Nicky_Hayden_Valencia_02.JPG

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Keith Code teaches students to hang off with the body "long" and low, parallel to the bike, ie. not crossed up over the tank with limbs sticking out. The subject has been discussed here ad infinitum and you can undoubtedly find dedicated threads including posts by Keith and the riding coaches explaining the "why" of it if you use the search feature at the top right of the page.

 

I think your BP in the first picture looks pretty good according to CSS's program.

 

I could speculate all day about the reasons why some pros don't do it that way. For instance, I think the specific technique is relatively new (in the last ten years) and many pros undoubtedly trained before Keith started teaching it and simply don't know about it. It was not a part of the curriculum when I trained with the school some years ago. Many racers around the world surely never took the CSS school at all. Or even trained with anyone at all. They are merely doing what comes "naturally" for them. Then there is your point about personal preference, what works for them, etc.

 

I don't have time to get into the science right now, in the meantime, check out this cool physics course website or one of the many others you can find with a search engine like Google:

 

http://www.glenbrook.k12.il.us/gbssci/Phys/Class/BBoard.html

 

 

racer

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OK, so first answer is Level 3 and we will get into this in real detail,. Pretty much the whole day (except the last class) is devoted to this subject, and the first class will really help.

 

Did you ride the lean bike in Level 2? If so, we should have sorted out how to anchor to the bike so as not to input undue bar pressure. Let me know on that, then let's go to the next thing. I'll be in a bit tomorrow, then gone to Vegas, but I'll get back to this! :)

 

Cobie

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Scientifically speaking:

 

This is my idea of what is happening with the physics of a motorcycle when a rider hangs off. If anyone has a better answer, please speak up.

 

OK...so...in general, getting your body mass low toward the inside of the corner is the goal. Being 'crossed up' by having body mass (head, torso, etc) up over the bike negates the effect of the mass of the other body parts (hips, butt, leg, etc) that are hung off. In other words, if you are going to be really crossed up, there is no point in hanging off. It won't really accomplish anything.

 

As for the idea of "getting weight over the bike to put more weight on the tires" ... first, scientifically speaking, we need to separate the concepts of mass and weight. Mass is a measure of matter, weight is an effect due to a force like gravity. On Earth, 1 kg of mass weighs 2.2 lbs due to gravity. Being that gravity on Earth is constant (at 1g), this relationship is consistent all over the planet, hence, one may express weight in kilograms without confusion ... here on Earth. However, if we travel to the Moon, 1 kg weighs ~ 0.36 lbs as the force of gravity is only 1/6 what it is on Earth (or about 0.166g). So, mass remains consistent regardless of forces applied. Weight does not.

 

Cornering creates "lateral g force" toward the outside of a turn. The amount of lateral force required to create the same weight going sideways as gravity creates going down is, again, 1g ... 1g of lateral force. Sports cars are often rated for the amount of "lateral g-force" they can create.

 

When leaned over cornering on a motorcycle, the force of gravity and the lateral g-force are balanced around a common lever (or moment arm) drawn between the center of mass and the contact patch of the (rear?) tire and create "weight" in both directions ... down and sideways. Basically, the angle at which the lateral force (weight) equals the vertical force (weight) is where the bike will balance.

 

By hanging off, we lower the center of mass for bike/rider which, first, reduces the length of the lever (moment arm) overall and increases stability (it takes more force to move a shorter lever than a long one). More importantly, a CoM offset from the centerline of the bike, or biased toward one side of the bike, leans that CoM/lever away from the balance point (between cornering forces and gravity forces), hence, the bike has to stand up more to remain balanced at that speed, sort of like a counterweight allowing the bike to balance the same cornering force (same speed) with less lean. (Think sidecar monkey.) Or, to turn it around, it allows the bike/rider to balance more cornering force (go faster) than if they didn't hang off at a given lean angle. To say it another way, one can go faster at the same lean angle if they are hanging off than if they aren't. And, hence, they can lean further and go still faster.

 

Now, what happens if you climb on top of the bike to "add more weight to the tires"? By definition, the bike must then lean over more to remain balanced and tracking on two wheels. So, we can't really consider vertical weight in isolation when shifting mass around on the bike. For every gain here there is a loss there as CoM must reamin balanced wrt gravity and lateral G's.

 

I have ignored a critical point regarding turn radius vs cornering forces, ie. if hanging off allows you to use less lean angle for the same speed, what happens to the turn radius? Will it remain the same?

 

Whadya think?

 

 

r

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I have ignored a critical point regarding turn radius vs cornering forces, ie. if hanging off allows you to use less lean angle for the same speed, what happens to the turn radius? Will it remain the same?

 

http://www.glenbrook.k12.il.us/gbssci/Phys...cles/u6l1e.html

 

From: Equations for Circular Motion

 

 

Fnet = m * V2/R

 

 

So, it would seem that, in terms of force, speed and radius are proportional. If the throttle and velocity remain consistent, then radius must also remain consistent.

 

Hmmm...

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Excellent points and information!

 

I really appreciate the attention to details and yes, it does make sense.

 

Cobie, yes - I rode the lean bike during Level II and it really helped with my BP. My instructor basically forced me to ride the lean bike because I was scraping boots and footpegs due to not hanging off correctly.

 

Racer - I appreciate the comment regarding my BP in the first picture. And thanks for the scientific explaination. I have always been the type of person that requires proof. I never accept "it just is"...I must either see it for myself or have proof. Your post was excellent.

 

I guess looking at all the pictures of other riders/Pros threw me off because I thought I was doing it "right" and then I see all of these people with more experience and more skill than I have not hanging off the bike.

 

I never even thought about the fact that they might have never been taught or learned anything different.

 

After reading Cobie's comments, I am SO looking forward to Level III. I wish I could do it NOW.

 

Thanks guys...

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Ok, one more question...

 

I know that this one is very hard to answer because there are so many variables.

 

But, in the first picture (taken at T4, Talladega)...with all things being equal, how much more lean angle do I have available at that moment? Well technically, to use more lean angle I would need more speed to hold the same line...but yall know what I mean.

 

Those are 180/55 Pilot Power 2CT's.

 

I don't expect an answer like "5.3deg". But basically speaking, could I have leaned the bike alot more, a little more or that was about right?

 

I am having a track bike built and setup as we speak. It is an '07 750 and I will be running a 190/55 rear...and the Ohlins will be setup for that tire and my weight upon delivery.

 

So next question, take that same picture and insert my 750 with correct suspension settings and a 190/55 Pirelli SC2...how much more available lean angle would I have.

 

I generally use my knee as a reference point and I won't lean past the point of dragging my knee. Could I pick my knee up a little bit and get more lean angle without wiping out?

 

I know those questions are probably on a case by case basis and many not even be answerable. But most people say something like "keep going till you lay it down...then back off a little". I would rather avoid the 1st part of that equation. :)

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Ok, one more question...

 

I know that this one is very hard to answer because there are so many variables.

 

But, in the first picture (taken at T4, Talladega)...with all things being equal, how much more lean angle do I have available at that moment? Well technically, to use more lean angle I would need more speed to hold the same line...but yall know what I mean.

 

Those are 180/55 Pilot Power 2CT's.

 

I don't expect an answer like "5.3deg". But basically speaking, could I have leaned the bike alot more, a little more or that was about right?

 

I am having a track bike built and setup as we speak. It is an '07 750 and I will be running a 190/55 rear...and the Ohlins will be setup for that tire and my weight upon delivery.

 

So next question, take that same picture and insert my 750 with correct suspension settings and a 190/55 Pirelli SC2...how much more available lean angle would I have.

 

I generally use my knee as a reference point and I won't lean past the point of dragging my knee. Could I pick my knee up a little bit and get more lean angle without wiping out?

 

I know those questions are probably on a case by case basis and many not even be answerable. But most people say something like "keep going till you lay it down...then back off a little". I would rather avoid the 1st part of that equation. :)

 

Chaos;

 

There is not enough information in one static image to answer your question but let me answer it by asking you a question; what difference does it make? I don't mean to be provacative with my question because your question is not unique. Why I ask is because your other posts have suggested (to me at least) that you are interested in racing or at a minimum, how to get around the track as efficently (read quickly) as possible.

 

I have attended over 20 CSS Schools as well as CodeRACE and have Corner Worked at Pocono, Watkins Glen and Loudon multiple times and my recollection is that the School teaches the importance of turning the bike as quickly as possible allowing you to get the bike upright and back on the gas - period. They do not teach how to touch a knee or how to maximum lean angle because those are simply by-products of efficient cornering. Keith's books and his Coaches will tell you that as your lean angle increases, your options diminish in direct proportion to that angle because at steep lean angles you have loaded up that very small front contact patch considerably. Now add in any input changes like just a bit more angle or a bit more brake or too much gas and it becomes "see ya!" in a hurry. DAMHIK.

 

Otheres here may have a different perspective and I encourage them to join the discussion.

 

Kevin

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... how much more lean angle do I have available ... ?

 

Look at the unused portion of the tread at the edge of your tires. Some people refer to these as "chicken strips". That should give you an idea.

 

On the street I'll probably have 1/2" unused.

 

Riding school or trackday probably about 1/4".

 

Racing ... 0".

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Hi all.

 

I'd like to post a correction to a part of my scientific exploration of some of the forces involved in hanging off above:

 

When leaned over cornering on a motorcycle, the force of gravity and the lateral g-force are balanced around a common lever (or moment arm) drawn between the center of mass and the contact patch of the (rear?) tire ...

 

I have done some more reading on moment arms or the "lever" that is worked by gravity and lateral g force when leaned over and ... I think the sentence above applies only when all (or nearly all) of the weight is biased to the rear. If the weight is balanced 50/50 between front and rear, I think the moment arm should be drawn vertically from the center of mass to a spot on the ground between the contact patches.

 

I'm not really a scientist, I just play one on the web :P

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Thanks for the responses.

 

Kevin, you are 100% correct and i agree. My goal is not to drag knee. Dragging knee is a byproduct of good BP.

 

You are right, lean angle and dragging knee do not "matter" and yes...i am interested in maximizing my skills and eventually racing.

 

I guess i was just looking for a simply answer to a question that is not simply answered ;)

 

Most people use the suggestion of leaning till you lowside, then back up a little bit. Obviously i want to avoid the first part.

 

I know that lean angle will change with speed and BP. So i guess i should basically work on good and consistent BP. I think if my BP is consistent, then i can use my tires as a guide to how much available lean angle i have, like racer said.

 

As far as "chicken strips"...

 

On my street bike i have maybe 1/4-3/8 of an inch. On my track bike, i have maybe 1/8 of an inch...but it isnt noticeable. They basically look worn to the edges. So i guess that is my answer right there........

 

All things being equal as far as speen/line/tires, i need to improve my body positioning so i can get more speed without increasing lean angle.

 

Thanks guys.

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Prior to taking the L3 class, I over-analyzed all the potential variables. That's the beauty of the L3 class is the skills they teach are very simple. Things really began to gel for me as far as the "body positioning on the bike".

 

I too heard about "kissing the mirror". From some of the pictures it looks like some guys are leaned WAY over. Not much room for error IMHO. The pictures of the pros look like they have moved their butts parallel to the long axis of the bike.

 

I don't want to give anything away here, but hanging off is only half of the solution. Having your lower-body anchored is the other part.

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I have ignored a critical point regarding turn radius vs cornering forces, ie. if hanging off allows you to use less lean angle for the same speed, what happens to the turn radius? Will it remain the same?

 

http://www.glenbrook.k12.il.us/gbssci/Phys...cles/u6l1e.html

 

From: Equations for Circular Motion

 

 

Fnet = m * V2/R

 

 

So, it would seem that, in terms of force, speed and radius are proportional. If the throttle and velocity remain consistent, then radius must also remain consistent.

 

Hmmm...

 

But ... the rolling radius of the tire changes at different lean angles, doesn't it?

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I have ignored a critical point regarding turn radius vs cornering forces, ie. if hanging off allows you to use less lean angle for the same speed, what happens to the turn radius? Will it remain the same?

 

http://www.glenbrook.k12.il.us/gbssci/Phys...cles/u6l1e.html

 

From: Equations for Circular Motion

 

 

Fnet = m * V2/R

 

 

So, it would seem that, in terms of force, speed and radius are proportional. If the throttle and velocity remain consistent, then radius must also remain consistent.

 

Hmmm...

 

But ... the rolling radius of the tire changes at different lean angles, doesn't it?

 

If the body position is changed, it effects the weight front/rear, and can this then effect rake (by lowering/raising the front)?

 

C

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I have ignored a critical point regarding turn radius vs cornering forces, ie. if hanging off allows you to use less lean angle for the same speed, what happens to the turn radius? Will it remain the same?

 

http://www.glenbrook.k12.il.us/gbssci/Phys...cles/u6l1e.html

 

From: Equations for Circular Motion

 

 

Fnet = m * V2/R

 

 

So, it would seem that, in terms of force, speed and radius are proportional. If the throttle and velocity remain consistent, then radius must also remain consistent.

 

Hmmm...

 

But ... the rolling radius of the tire changes at different lean angles, doesn't it?

 

If the body position is changed, it effects the weight front/rear, and can this then effect rake (by lowering/raising the front)?

 

C

 

Welll... there is increased cornering force compressing the suspension at higher speed/lean angles and vice versa.

 

Soo... then the rake would change between being leaned over more and less. Hence, the steering geometry would be altered, ie. the front wheel would be turned in more or less, no?

 

Aand... it would then seem to follow that the more weight biased toward the front, the more effect there will be...

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I don't agree at all with the idea that you have to crash in order to know how far you can lean.

 

Obviously there are so many constantly changing variables ... tire model, tire temp, tire wear, track temp, track cleanliness, pavement type/texture, suspension settings, suspension oil temp, body position, rider inputs, on and on and on. To have to do this lean 'till you low-side experiment for each combination of variables would be very expensive and probably painful and you could never remember all the answers anyway.

 

My philosophy on this is to do everything GRADUALLY.

 

If you GRADUALLY roll-on the throttle coming out of the turn, then the worst that is likely to happen is your rear tire will slide just a little and it won't be that scary and you can back off before it gets out of hand. If you whack the throttle open all the sudden at a low lean angle then you are very likely going to crash.

 

If you don't have any sliding at all then you might think, hmm, I could gain more speed there if I roll on a bit heavier, which is true, just increaese the roll-on very very GRADUALLY from lap to lap so that you don't ever SUDDENLY go WAY over the limit.

 

If you come out of pit lane and do one lap nice 'n easy, 2nd lap a little faster, and 3rd lap maybe is full speed, GRADUALLY coming up to speed, then if your tires have been through one-to-many heat cycles you'll figure that out in a nice easy way somewhere in the 2nd lap.

 

If you GRADUALLY over the course of many track days increase your speed then once again you will be given some friendly hints that you are getting close the limit in certain situations in the form of some gentle sliding, rather than having to crash. In about maybe 50 track days all on the same track (VIR North Course) my lap times have gone from about 2:05 to 1:45. That means I can now do 6 laps in the same amount of time it used to take me to do 5. (The pros can do 6 laps in the time it currently takes me to do 5.) Never at any point did I feel that i was "pushing" it to a point of feeling uncomfortable. I just kept practicing and concentrating on the skills and naturally ended up GRADUALLY going faster. Only recently I occasionally had some moments where I felt some sliding, mostly when the tires had come to the end of their usable track life. When the sliding did happen though it was surprising to me that it wasn't scary. I specifically remember one incident in turn 1 lap 2 after 3.5 track days on the same rear tire. The rear just slid out under throttle and I musta flattened out my throttle roll on and it came back in totally smooth and probably nobody other than me even knew about it. The rear tire was toast, but because I was gradually coming up to speed in that session, and was gradually rolling on the throttle, I was made aware of the situation with no drama.

 

When a rider starts to push it to the point of feeling uncomfortable, that's when the big unpredictable scary slides/crashing happen.

 

The other thing I've noticed is, that sometimes I get caught up in trying to drag my knee more and lean lower, and then I remind myself to look ahead for the reference points and concentrate on actual cornering speed and throttle control, and whenever I do that, what d'ya know I end up leaning lower and dragging my knee more and no doubt going faster.

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Welll... there is increased cornering force compressing the suspension at higher speed/lean angles and vice versa.

 

Soo... then the rake would change between being leaned over more and less. Hence, the steering geometry would be altered, ie. the front wheel would be turned in more or less, no?

 

Aand... it would then seem to follow that the more weight biased toward the front, the more effect there will be...

 

Let's just look at one piece of this--rake: if their is more weight on the front, will that compress the front and in effect, steepen the steering angle? Will that then make it easier to steer the bike (let's say rider has not yet come back on the gas)?

 

C

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Welll... there is increased cornering force compressing the suspension at higher speed/lean angles and vice versa.

 

Soo... then the rake would change between being leaned over more and less. Hence, the steering geometry would be altered, ie. the front wheel would be turned in more or less, no?

 

Aand... it would then seem to follow that the more weight biased toward the front, the more effect there will be...

 

Let's just look at one piece of this--rake: if their is more weight on the front, will that compress the front and in effect, steepen the steering angle? Will that then make it easier to steer the bike (let's say rider has not yet come back on the gas)?

 

C

 

 

Yes, if the front forks are compressed, the rake will be steeper, hence, the steering geometry will be "quicker".

 

I am assuming by context that the rider in your hypothetical scenario is causing more weight to be on the front by body position and merely decelerating off the gas but not on the brakes?

 

 

 

PS: Your original question was posted in reply to a question of mine about whether or not a bike maintains turning radius when hanging off to reduce lean angle at a given speed, in other words if you ride the same corner at the same speed hanging off, will the bike turn the same radius as not hanging off at the steeper lean angle. I didn't see the connection of your question to my question, hence, why I talked through the other conditions of more suspension compression at higher cornering speeds to see if I could make the connection.

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Scientifically speaking:

 

As for the idea of "getting weight over the bike to put more weight on the tires" ... first, scientifically speaking, we need to separate the concepts of mass and weight. Mass is a measure of matter, weight is an effect due to a force like gravity. On Earth, 1 kg of mass weighs 2.2 lbs due to gravity. Being that gravity on Earth is constant (at 1g), this relationship is consistent all over the planet, hence, one may express weight in kilograms without confusion ... here on Earth. However, if we travel to the Moon, 1 kg weighs ~ 0.36 lbs as the force of gravity is only 1/6 what it is on Earth (or about 0.166g). So, mass remains consistent regardless of forces applied. Weight does not.

 

uhmmm.. kg and lbs measure the same thing...mass. It's just that the kg is ISO and lbs is imperial system.

1kg is approximately 2.2 lbs everywhere.

Now, the gravitational force (the weight, or the force pulling a corp towards the center of the Earth) is G=m*g where m is the mass and g is the gravitational acceleration and it is considered a constant (it's almost the same everywhere on Earth) and is about 9.8 meters/square second.

So one kg of mass will be pulled down with a force equals with 9.8m/s^2, or 9.8 N, where N (Newton) is the ISO unit for force.

A given body will have the same mass on the earth and on the moon, but its weight on the moon will be only about 16% of the weight as measured on the earth, because the gravitational acceleration (g) on the moon is lower than on Earth.

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