[ARWUN]

Re: Arwuns' complaint

Arwun,

They disallowed the charge to us mate, I'd be happy to fax you a copy of it.

Keith

Sure; should I p.m. you with my fax number?

 

[Keith Code]

defining body steering

OK, by shifting your CofG rapidly you can effect some input into the bike that will alter its direction. As in Trevitts demo on the No BS bike.

Downside is there is a lag between the body motion and the direction change.

It sounds like the one agreement point is that a shift of body mass must accompany a body steering action.

If that is indeed the case then from our original list that eliminates footpeg pressure and tank pressure--unless accompanied by a shift of body mass i.e., CofG.

Without the accompanying change in CofG it is, as someone said, like trying to push your car by applying pressure to the dashboard.

Just because it follows Newton's second law, is this really going to fly with Body Steering guys?

Keith

PS: Arwun, how much did that azzhole (me) charge you for hitting the garage at Mid Ohio?

 

[winders]

Re: defining body steering

It sounds like the one agreement point is that a shift of body mass must accompany a body steering action.

No, I don't think so. Did you skip over the posts that discussed the effects of peg weighting? There do not have to be significant shifts in body mass to weight pegs. I believe Vish discussed the physics of what happens when this is done. Maybe he will clarify those points again....

Scott

 

[Andrew Trevitt]

Re: defining body steering

Downside is there is a lag between the body motion and the direction change.

It's not so much that there is a lag, but in some situations your body is in the wrong position to begin with-you have to get in the right position first.

AT





AT

 

[Andrew Trevitt]

Re: Re: defining body steering

No, I don't think so. Did you skip over the posts that discussed the effects of peg weighting? There do not have to be significant shifts in body mass to weight pegs. I believe Vish discussed the physics of what happens when this is done. Maybe he will clarify those points again....

Scott

I can't find any physics that shows you can move something while solidly attached to it, unless you offset your cg and use that to create a torque-meaning you have to move into position first. I'm thinking of something like a ladder falling over. And, I scared the crap out of myself on Keith's No :bs bike by trying to ride it without moving.

Consider this, Scott: when you push down on a peg, you have to brace yourself against something-say your thigh on the seat, or your knee on the tank. This will make an opposite torque to the one made by your foot on the peg, cancelling out most of the effort.

AT

 

[KneeDragger77]

Man, this thread is great! I'm smarter already:sneaky Keep it coming guys

 

[Keith Code]

AT said.

Consider this, Scott: when you push down on a peg, you have to brace yourself against something-say your thigh on the seat, or your knee on the tank. This will make an opposite torque to the one made by your foot on the peg, cancelling out most of the effort.
------------------

AT and Winders,

Cancels out ALL of the effort.

AT,

When you say it's not so much that (refering to the lag in throwing your body mass at the bike and the actual alteration of direction) that is a factor and is important, certainly in street riding/accident avoidance situations where you don't have time to prepare.

I know what you mean, you have to kind of wind up and pitch your upper body at it but really, what would Mat Mladin or Doug Chandler look like if they did that--Hippo Ballerinas I think.

Keith

 

[winders]

AT said.

Consider this, Scott: when you push down on a peg, you have to brace yourself against something-say your thigh on the seat, or your knee on the tank. This will make an opposite torque to the one made by your foot on the peg, cancelling out most of the effort.
------------------

AT and Winders,

Cancels out ALL of the effort.

Keith,

No, that is not correct. You do not have to brace yourself to unweight one peg and transfer that weight to another. Vish described what happens when you transfer weight.

Scott

 

[vish]

Re: Re: Re: defining body steering

I can't find any physics that shows you can move something while solidly attached to it, unless you offset your cg and use that to create a torque-meaning you have to move into position first. I'm thinking of something like a ladder falling over. And, I scared the crap out of myself on Keith's No :bs bike by trying to ride it without moving.

Consider this, Scott: when you push down on a peg, you have to brace yourself against something-say your thigh on the seat, or your knee on the tank. This will make an opposite torque to the one made by your foot on the peg, cancelling out most of the effort.

AT

what if i don't brace myself against the tank.. there will be a resulting unbalanced torque on the body that tries to close the gap between bike and rider.

Any unbalanced peg weighting will result in a force/torque that acts oppposite to the resulting tourque/force the body to the one the body applies on the bike (netwons second law)

but AT your statement that you need to move first inorder to apply torque is not true.. i can start to apply a torque without any displacement.. but by applying any resultant force on the bike... an unbalanced force/torque on you which .. if you were stationary w.r.t to the bike will try to move you.

example.. i'm leaning to the left and the body carries more role rate to the left that the bike.. apply force on left peg.. bodies role rate will reduce.

in pratice you would want to be hanging off quite a bit.. or you need to be rolling(about the role axis) when you try and use B.S... i think it is important that we differentiate movement of CoG with a rate of rate of change of displacement(acceleration)


lets define B.S. this way..
first we establish role, pitch and yaw axis on the bike.

Any steering action that results from an unbalanced torque applied by the rider on the bike along the role axis of the bike.

i think it safely excludes C.S. and possible shifts of body to change weighting on the front and the bike of the bike or lowering/raising CoG actions to change geometry or weight shifts.

at first sight it might seem that using B.S. might result in no changes of line.. since the bike will apply the opposite torque on the rider and the there will be no external torque on the rider/bike system.

the following reasons will result in a increase in lean of the bike/rider system when you us B.S. (in no particular order)

1. trail of the bike will lead to change in steering angle which will lead to bike dropping into the turn some more.. (this is a slow change.. we can get into why if people want to)

2. increased lean angle of the wheels will result in increased camber thrust that leans the bike some more.

3. torque on the gyroscopic momemtum when applied on the role axis will transfer some of it into the yaw direction... while leaned over not only will this result in a tightening of the turn but will also seem to lift the rear a little bit and put some weight on the front.

so when we use B.S. we will see changes in line.. and different demands on front and rear tires compared to using C.S. (which derives most of its sterring traction demands off of the front tire)

we havnt figured out how much of a change in line we can get from B.S. but i hope this offers some explanation into why B.S. might work... but isnt it useful to learn a technique that might be able to change the line without having to use as much traction off of the front?

vishnu

 

[Keith Code]

Re: Re: Re: Re: defining body steering

1. trail of the bike will lead to change in steering angle which will lead to bike dropping into the turn some more.. (this is a slow change.. we can get into why if people want to)

2. increased lean angle of the wheels will result in increased camber thrust that leans the bike some more.

3. torque on the gyroscopic momemtum when applied on the role axis will transfer some of it into the yaw direction... while leaned over not only will this result in a tightening of the turn but will also seem to lift the rear a little bit and put some weight on the front.

... but isnt it useful to learn a technique that might be able to change the line without having to use as much traction off of the front?

vishnu [/B][/QUOTE]

-----------------------------
Vish,

What I don't get (from lack of understanding) is how numbers 1,2 and 3 above change.

Are you saying that weighting a peg rather than, say, allowing most of your weight to remain on the seat, has enough leverage on the bike to effect these changes? Is it the leverage from the peg being outboard of the center of mass that is creating this?

For example if you put your weight on the engine cases like over your clutch cover would that affect it less?

Keith

 

[Eyespy]

Re: Re: Re: Re: Re: defining body steering

1. trail of the bike will lead to change in steering angle which will lead to bike dropping into the turn some more.. (this is a slow change.. we can get into why if people want to)

2. increased lean angle of the wheels will result in increased camber thrust that leans the bike some more.

3. torque on the gyroscopic momemtum when applied on the role axis will transfer some of it into the yaw direction... while leaned over not only will this result in a tightening of the turn but will also seem to lift the rear a little bit and put some weight on the front.

... but isnt it useful to learn a technique that might be able to change the line without having to use as much traction off of the front?

vishnu

-----------------------------
Vish,

What I don't get (from lack of understanding) is how numbers 1,2 and 3 above change.

Are you saying that weighting a peg rather than, say, allowing most of your weight to remain on the seat, has enough leverage on the bike to effect these changes? Is it the leverage from the peg being outboard of the center of mass that is creating this?

For example if you put your weight on the engine cases like over your clutch cover would that affect it less?

Keith [/B][/QUOTE]

Vish and Keith,

A mechanical effect to change the bike's direction with peg weighting independant of bar inputs is only present if the combined effective rider/bike CoG changes as well. This goes back to the infinately long foot peg principle.

 

[Keith Code]

traction on the front

... but isnt it useful to learn a technique that might be able to change the line without having to use as much traction off of the front?

vishnu
---------------------

Forgot to comment on this. Yes and no, depends on the bike and its set up, of weight distribution, steering head offset and so on.

AS an example, EBoz runs a lot of front spring so he can trail the brakes hard into corners (so I have been told) and still have plenty of travel that isn't on the bottom of the overall fork travel. He uses that very forward and down position which compensates for the setup to a degree so he can ride it mid corner and not have it understeer, which it would do if it were too light.

Riders get used to setups and can't change, they just like it that way. Even, in some cases, when the lap times say it is better. If they don't like the "feel" it don't fly. I have examples.

Here is one you might like.

I set up a deal where team Kawasaki brought Eddie Lawson out to Riverside Raceway in 1982 on his SUperbike. He was going to test a device called the ATK. The device was a set of rollers that mounted on the swingarm (one above and one below, close to the swingarm pivot) that carried the chain straight forward off the rear sprocket with no dip in it as usual when it goes down to the countershaft sprocket. In other words the chain ran in parallel lines off the rear sprocket up to the device and then dropped to the countershaft.

The pupose of the device was to eliminate chain torque and therefore liven up the rear suspension under acceleration load.
It did make the suspension more compliant under acceleration and he did go over 1/2 second quicker with it in only three laps. Didn't like the feel and that was that.

Keith

 

[Andrew Trevitt]

Vish and Scott: If your cg hasn't moved from a stedy-state cornering situation, and you sum torques around say, the bike/rider roll axis, you get no change when you apply that weight to one footpeg, the seat, or the other footpeg. In your example, Vish, if you have more roll rate than the bike, doesn't that mean you have to be moving wrt the bike?

Have you ridden Keith's bike? Have you ridden no hands and tried it?

Camber thrust, yaw rotation, and the change in steering angle all happen with body steering as well as counter steering. Both BS and CS rotate the bike around the roll axis, bringing about these other results.

Vish also says:

" we havnt figured out how much of a change in line we can get from B.S. but i hope this offers some explanation into why B.S. might work... but isnt it useful to learn a technique that might be able to change the line without having to use as much traction off of the front? "

and I think this is a critical point. If you're at maximum lean and have to bring the bike more upright to correct a small slide, which would you rather do? Add turning forces to an already overloaded front tire, or move your body a bit off the bike to force the bike more upright?

AT

 

[vish]

Vish and Scott: If your cg hasn't moved from a stedy-state cornering situation, and you sum torques around say, the bike/rider roll axis, you get no change when you apply that weight to one footpeg, the seat, or the other footpeg. In your example, Vish, if you have more roll rate than the bike, doesn't that mean you have to be moving wrt the bike?

Have you ridden Keith's bike? Have you ridden no hands and tried it?

Camber thrust, yaw rotation, and the change in steering angle all happen with body steering as well as counter steering. Both BS and CS rotate the bike around the roll axis, bringing about these other results.

Vish also says:

" we havnt figured out how much of a change in line we can get from B.S. but i hope this offers some explanation into why B.S. might work... but isnt it useful to learn a technique that might be able to change the line without having to use as much traction off of the front? "

and I think this is a critical point. If you're at maximum lean and have to bring the bike more upright to correct a small slide, which would you rather do? Add turning forces to an already overloaded front tire, or move your body a bit off the bike to force the bike more upright?

AT

AT.. i don't there can be any B.S. without an unbalanced force/torque by the rider on the bike..

and i agree with what you were trying to say about movement of the riders CoG for B.S. but i wanted to make the point that there seems to be too much importance placed on movement.. where instead all that happens when you apply a force or a torque is accelration (linear or angular) n this might lead to slowing down of rider movement (in the example i provided)

if all the forces (and torques) applied by the rider on the bike balanced themselves there is no B.S.

i'm not sure how much the roll to yaw tranfer helps turn the bike in the B.S. case.. but that will be one important use of B.S.

so do you like to continue for a while to use this definition of B.S.

"steering changes that are caused by an unbalanced torque along the role axis applied by the rider on the bike"

also i havent tried keith no BS bike.. i have tried riding with my hands on the tank..several times in the last week to figure out what it feels like..
i would sure like to try it some time and see if it feels any different..
i found tony foales comment about the no BS bike in his book interesting

"Rider comments do seem to indicate that it was harder to ride than doing it "no-hands". This is probably a psychological effect, the lack of a normal response from the handle-bar conflicting with the riders subconsciour expectations"

also i'm suprised non of the big guys(manufacters) have detailed simulation models that can help figure out all of this and help riders understand what they are doing.. while riding is a more feel than science i for sure would like to know why what i'm doing does what i want it to do.

vishnu

 

[51ways]

Here are a few more thoughts on peg weighting, etc.:

I. One can drive straight down the road, with all body weight supported primarily at two points : (1) either peg and (2) pushing on the opposite handlebar. Note that your body weight is raised off the seat. Note that some small weight may be put on other peg simply to stabilize your body position. However, the steady roll attitude (while traveling straight) of the motorcycle for the given speed is established by how much weight is carried by the primary peg (and equilibrated by an amount of countersteer).

II. One needs to push on the opposite handlebar for two reasons: (1) To stabilize your body position and (2) to provide a steady countersteering input to maintain straight travel.

The difference in steering effort require to turn the bike from this confguration as compared with from the normal seating position is large: In this configuraton, one can simply reduce pressure on the opposite bar to see how quickly the bike will fall into a turn.

The reduction of say this "positive" countersteer pressure is identical to the application of negative countersteer pressure, applied to the bike when traveling in the typical vertical configuration.

The weighting of a peg could be considered a "body steering" input. However, I will propose that this weighting of a single peg ("weight lateral bias", to coin a phrase) in a sense "preloads" the chassis, such that a REDUCED countersteer effort is required. As already mentioned, this effort may simply involve the reduction of the steady countersteer that is required to maintain the current heading once the bike is weight lateral biased.

The point here I think is that a rider may shift their body weight simply to facilitate quicker response to countersteering, rather than to actually provide a steering input. In fact, since this reduced counter effort can be established regardless of how slowly one shifts the weight, this is clearly a body weighting issue, not a body steering issue as a weight shift that happens slowly cannot generate significant inertia forces to actually steer the bike. The inertia forces generated by a true “body steering” input are a secondary input (and these inertia forces are reacted by body support points, inluding bar pressure).

Therefore, I can see two categories of inputs, as has been proposed in earlier posts:

1. Weighting (weight lateral biasing) to quicken the response to countersteer (including quckening the response to a reduction in countersteer effort)

2. Body inertia inputs: this would be the forces applied to the chassis by moving the body quickly enough to generate accelerations of the body (inertia forces) relative to the chassis. Note that the forces generated by the rider to provide reactions to the pending inertia forces are NOT the same as the inertia forces. One can provide countersteering pressure and peg weighting to react a body shift to one side or the other. As all such forces must be reacted by internal forces applied to the chassis by the rider, as riders, one can discern such “subtle” means of reacting these body motions, by simulteously, and to varying relative magnitudes, anchoring the body by pushing on peg, on tank, and above, modulated countersteer to both stabilize the body, and to negate the influence of the somewhat unconscious pushing and pressing the body does PRIOR to atually shfiting the body mass quickly. In other words, there are two phases of a mass shift (body steering input): One is this subtle "preparation" for the shfit, and then the shfit itself. The preparation could be simply increasing countersteer pressure on opposite bar prior to (and required by) the "quick" mass shift to the side.

Josh Gordis

 

[ARWUN]

Re: defining body steering

Arwun, how much did that azzhole (me) charge you for hitting the garage at Mid Ohio?

Keith ~ I’m not sure exactly how much the bills came to. If the total of both charges wasn’t $1,200, then I apologize for the mistake. If you have a cap of $750 on damage, then the total came to $1,150. The point is that you actually had the audacity to encourage a student to ride an experimental contraption with no stopping controls while performing any means necessary to turn the bike in a very narrow area, and then when the bike did turn and hit the wall, you charged for the damage. Charging for damage to one of your rental bikes that is the rider’s fault is expected; charging for an accident that is not the operator’s fault is ludicrous. It is the same as if CSS forgot to fill the brake reservoir with fluid on one of the rental bikes, or tighten an axle nut, and then when the rider crashed, charging him for the damage… regardless if it is $1,200, or $0.01.

When can you fax a copy of the deleted charges to me? It seems very strange to me that my credit card company would screw both of us, and keep the money. They told me that I paid, and told you that I didn’t have to pay.

BTW, I have not “badmouthed” you or your classes any more than many others on these forums. When people ask about CSS, I tell them that it is an excellent class if they are a beginning rider because the are forced to start out in Level I. I tell them that it is very organized, and the on-track stuff is very safe. However, I encourage anyone that is already comfortable on a track to consider another school because fast passing is not tolerated and the lessons are pretty basic. If someone has the time and money to take Levels I-IV, then it would probably be beneficial to anyone. My problem is that the first couple days and $400-$800 is not a very good bang-for-your-buck… if you have experience. And of course, I warn them about the no-BS bike. I recommend that they ride it to feel how much countersteering can add to a turn, but tell them to make sure that they ride it in a open area, go above 30mph, and to just apply a small amount of BS. I also tell them to be ready to quickly switch back to the real bars if anything goes awry. I also suggest that they don’t sign a damage liability form, if they are not using one of the rental bikes. These are some of the exact same comments that other graduating students have made.

 

[Keith Code]

Arwun,

Were you charged and did you pay $1,200 as you posted or not.

Keith

If you are unclear on this I can fax you the bill you signed at the
track, I will also fax you the statement disallowing the charge. Then you can answer my question and clear it up for these good folks on the R1-Forum.

send me your fax number.

 

[KneeDragger77]

Glad to see you guys are working this out. Thanks for the E-mails too Keith!

 

[ARWUN]

Arwun,

Were you charged and did you pay $1,200 as you posted or not.

Keith

If you are unclear on this I can fax you the bill you signed at the
track, I will also fax you the statement disallowing the charge. Then you can answer my question and clear it up for these good folks on the R1-Forum.

send me your fax number.

Yes. I was charged, and I did pay, as I posted. I’m not sure how much the bills came to, as I also posted. If you would like to fax the final decision from my credit card company disallowing the charge (not the initial dispute claim, obviously), then that would be great. I don’t really need to see anything that I was forced to sign against my will. I’ll PM you with a fax number.

I wasn’t aware that any of these good folks on the R1-Forum were desperate to know exactly what you charged me. Who cares?

 

[Viper333]

Re: Defining body steering

Originally posted by Andrew Trevitt

Consider this, Scott: when you push down on a peg, you have to brace yourself against something-say your thigh on the seat, or your knee on the tank. This will make an opposite torque to the one made by your foot on the peg, cancelling out most of the effort.

AT [/B]

Sorry, but due to lack of time I havent been able to completely follow up on this thread but after reading the quote above it brought to mind CF. (Centrifugal force). Has CF been covered?

As an example, take the guys that ride their bikes in a large drum and go around in circles stuck to the wall. Technically if you went fast enough you would have zero weight side loading the tank and it would be possible to put all of your weight on either peg.

Now, to a lesser degree I believe the CF would have an effect with peg weighing and effectively alter the CoG due to leveraging over the contact patch
Of course the CF would be infinitely variable due to degree of banking, speed, radius of corner etc.

Any thoughts?