[Eric]

Here is the biker towards the end of the second turn. He is in a steady state turn.


Now he will slightly overcontrol, turning the wheel towards the inside of the turn, this will create an unbalance of forces that will stand him up.


His earlier over steer has now stood him up vertically. He is ready to enter turn three. Note that his front wheel is pointed away from the direction he plans to turn, he is countersteering at this moment, creating a lateral force at his contact patch that will move the bottom of the bike out from under him and lean him into the next turn.


In this image he has already started to lean and his wheel is still pointed to the outside of the turn. He is still countersteering and it is still causing the bike to lean. He is decreasing the angle slightly to slow the speed that he is falling/increasing his lean.


In this image his wheels are in line, neither steering nor countersteering. As such no forces are generated at the tire to stand him up or cause him to fall to the inside, however gravity will lean him using the horizontal distance between the contact patch and the center of gravity as a moment arm. (This is why when leaning to avoid falling over you have to angle the wheel toward the inside of the turn, to counteract gravity.)


Now he begins to turn the wheel in the direction of the turn. This is when "normal" steering begins. Not being aware of the initial counter steer does not stop it from existing. He doesn't quite have it turned enough to fully counteract the lean force caused by gravity at this point, but it is quite close.


In the last images he continues to turn the wheel into the turn untill he reaches an angle that will generate a force that will prevent gravity from continuing to drop him on the inside.




After he will turn his wheel more to the inside of the turn, which will stand him up, then he will continue into the next turn, as described above.

Also if anyone is still leery about slow speed countersteering I'll rig up a video camera with a steering angle indicator to demonstrate conclusively. As soon as the wheels begin to move all increases in lean are caused by countersteering followed by no steering, all steady angle leans and decreases in lean are caused by positive steering (Toward the direction of lean) At any speed you want to see it done at.

[ben segrest]

I just got back from the carwash and as I was pulling up, I ran a 4 second experiment. I was moving at somewhere between half and 3/4 walking speed. I removed as much weight as I could from the bars, but kept my hands feathering the clutch and throttle and rear brake was dragging. I don't think my speedo was even registering anything, BUT I observed countersteer! I think that everybody involved in this thread should go get on their bike and try it before this discussion continues. I don't mean that in a smug way; my veiws on how motorcycles work are changing having read this thread and tried it myself. So yall go try then we'll talk some more.

[Mojoe]

Eric....I buy your explaination in that video.....but even he is rolling much faster than I intended to use as an example for this thread.
set up your camera and explain the whole thing at crawling speed.
I guess you can say there is some counter steering involved when you see the front wheel keep flopping from one side to the other. That is the slow speed I want to see you explain.

[md86]

At all speeds

I am talking at everything from just barely rolling to screaming like a banshee, physics doesn't change with speed, our kinesthetic perception and the handle bar forces change, giving us the illusion that the controls change.

Sorry , I ain't buyin it . I move at REALLY slow speeds quite often , and I'm ALWAYS pointing the bars in the direction I need to go with no countersteering . I PROMISE .

[Mojoe]

At all speeds

I am talking at everything from just barely rolling to screaming like a banshee, physics doesn't change with speed, our kinesthetic perception and the handle bar forces change, giving us the illusion that the controls change.

Sorry , I ain't buyin it . I move at REALLY slow speeds quite often , and I'm ALWAYS pointing the bars in the direction I need to go with no countersteering . I PROMISE .

yup....I feel the same way. I was just out in the parking lot this morning to examine exactly what is going on, and there is no countersteering involved. Just like riding a bicycle.
So unless you have some university degree in mathematics with some kind of formula that can DEFINATELY make me feel different about it, I am not buying it either.

Who knows Matt.....we might just be stupid.

[Eric]

Hello, I'm not trying to insult you two, or insinuate in anyway that you're stupid, just that you've failed to notice a subtle and very commonly overlooked part of motorcycle and bicycle riding.
I've been lurking since late january when I got the Kat (registered in March) and respect both of you as being very knowledgeable.

In this video I deliberately introduce a very large counter steer to very quickly lay the bike over. I couldn't do that large of a countersteer at anything but very slow speeds or I would lowside in a split second. (Even at 5 or ten miles an hour an input as large and abrupt would lowside you in a heartbeat.)

As I said earlier countersteering starts a lean, no steering or futher countersteering increases your lean. Habitually in low speed manouevers I don't run as much lean as in the video, and thus need less countersteer to initiate. (And perhaps you don't run much lean either, resulting in such a small and quick countersteer that you don't realize it happened.) But it still works the same, at all speeds.

Like you can see in the later higherspeed turn, the needle still shows countersteer, then normal steer, then more normal steer (Or a speed increase) (But the countersteer is very quick and very small.)

To reiterate again (Pardon the repetition.)

From a vertical position all leans are started by some form of steering, since a lean in a desired direction is caused by steering opposite the desired direction of travel this is known as countersteering.

The degree of the countersteer changes the rate at which the bike will lean.

As soon as the bike begins to lean, gravity also assists in continuing the lean.

Positive steering is used to prevent the bike from falling over (arrest the lean) and to provide the acceleration to make the bike take a curving path.

Further positive steering (or a speed increase in conjunction with some angle of positive steering) will stand the bike up.

Effects such as tire and suspension geometry (weight shifting affects this allowing slow rate (not nessecarily slow speed) turns to be made),
gyroscopic precession,
and the bikes rolling rotational inertia (both the wheels, engine, and the inertia of the frame itself)
all have a small effect on the motorcycles turning, either hindering, or helping, or just resulting in forces felt at the handlebars, but are almost completely insignifigant in comparision to the effect of the front wheel's path on the ground.

At higher speeds the front suspension geometry will make it feel as though you are holding a countersteer through the entire turn, when as the video showed it is just a transitory initial countersteer followed by positive steer.

At lower speeds most don't desire to lean very far, and thus only a small nearly unnoticeable countersteer starts the bike leaning and is quickly caught with a larger normal steer, but it still exists.


I don't have a university degree in math yet (I'm heading to be an aerospace engineer) But I have enough math and college physics background to provide diagrams and equations for the entire turning operation. Which, as with the video, I'll be happy to provide if you aren't convinced, or would like to further your understanding of motorcycle control.

Lastly I'd like to state that while I know the physics are right the way that things are percieved from the seat make a lot of what I'm saying seem counter intuitive. (For example, in a high speed turn you aren't countersteering through more then a fraction of the turn but it feels as if you're turning the bars in a countersteer the whole way through.)

I respect both of your knowledge and the practical experience you both have with riding motorcycles and hope to continue benifitings from it in the future.

[Eric]

The video

When explaining I say ". . . a larger initial steer to catch . . ."
Should be ". . .a larger normal steer to catch . . ."

http://members.cox.net/ericmarc-aurele/Slowsteering.wmv

I'd also like to add that as you can see when I'm rolling very slowly in a straight line I wiggle a bit from side to side, with it appearing as through I am only normal steering. But all those wiggles where I follow the needle were unconciously initiated by a very small, unnoticed by me countersteer (or residual normal steering from a previous wiggle acting as a countersteer for the next wiggle, as with the video Mojoe posted.) Unless you're throwing the bike over quickly the initial countersteer is very small and hard to detect.

[Eric]

Sorry to keep beating this dead horse,
but this evening I thought maybe I ought to make a video showing what happens when you don't countersteer.

http://members.cox.net/ericmarc-aurele/bikesteer.wmv

(Also I just got the video camera a few days ago and am enjoying being able to put videos on my computer.)

I did it on a bicycle because I knew it would cause me to fall. I encourage anyone unsure about slow speed steering to try it, from a straight line deliberately move your handlebars to one side and hold. Firstly it will be very hard to hold for more then a fraction of a second, it feels unnatural, you will want to turn the bars the other way and catch yourself. Secondly if you hold, you will go down like a brick. In fact the time I put my bars to my left you can see me at the end snap them to my right trying to catch the bike. (Also note that even though I moved them left I started to fall right and as I moved them right trying to catch myself I began turning to the right.)

Also I am not deliberately falling to make my point rather it is the only outcome that can follow from steering with out first countersteering.

[freight dog]

just dump the clutch and ride 12 o'clock's all over.
problem solved

Does anyone have a vid of a stunter doing the Motorcycle Operator Skills Test up on one? That would be hilarious!

[Mojoe]

After seeing the vid, I can't argue the fact that there is a small amount involved. so small that I never even noticed......so in my head it didn't exist....or even count.

I think we ate some crow on this subject, Matt.

good explanation Eric.

oh....and I never took anything as an insult. I was just kidding around with the "stupid" comment.

[md86]

Crow huh ? . Well , I'll pay closer attention next time I go out for a ride I guess .....

[ben segrest]

I tried to keep the crowes safe, but as usual, nobody wanted to listen to Ben. In your defense though, it is a very subtle amount of countersteer used at those crawling speeds.