Friday, October 15, 2010

Countersteering: Why Doesn't it Work at Low Speed?

Countersteering is often oversimplified into the expression "Push right to go right, push left to go left". The reason this expression is taught, is to help riders remember which way to push. Actually, countersteering also works by pulling the handlebar, and if you pull the handlebar, it would be "Pull left to go right, pull right to go left." My own feeling is that memorizing phrases like this is actually pretty useless. For one thing, your brain is too slow to steer and balance the bike if it has to process catch phrases, and for another, this is an oversimplification that ultimately prevents understanding of what you are doing.

Once you are told what countersteering is, it is your job to make it a subconscious reflex. Not to be constantly repeating phrases to yourself as you go around curves. I have been countersteering for forty years, and I never think about it any more unless I am doing something unusual. For example, let's say I am holding the right handgrip with my left hand. If and when I do that, I find out that my hand is unconsciously doing the WRONG thing to balance the motorcycle. By the way, this crossing your hands trick is a dangerous practice that I do not recommend trying. There is another time when my unconscious countersteering is bad, and that is when I am in deep gravel. In deep gravel, the front wheel should not be steered too forcefully, you have to be very gentle and balance the bike with your body more than you would on pavement.

Countersteering, once it becomes unconscious, is at work all the time, not just in curves or high speed. It works in a straight line, or in fighting a side wind. It works at low speeds and high speeds.

Next we come to this so-called exception to countersteering that you often hear about. It is said "countersteering does not work under 10 kph." I am suspicious whenever I hear of a law of science that has exceptions. Usually it means the law has not been properly formulated in the first place, and that it needs a rethink.

The fact is that countersteering is not simply a matter of "push right to go right." More correctly, it would be this: A motorcycle (or any two wheeled vehicle) actually must steer to the right to go to the right. But it is only in very sharp corners that you would actually turn the handlebars enough to see them turning. In a high speed gradual curve, you turn the handlebars so little it is almost invisible. But when turning around in your driveway, you need pretty much full steering lock to make the corner. So sharp corners (usually taken at low speed by the way!) need a visible amount of steering to get around. Gradual corners (a 100 kph onramp) only need an almost invisible amount of steering with the handlebars.

OK so now the actual steering is taken care of, let's deal with leaning. Remember at high speeds, the amount you turn the bars is almost invisible, but you need to lean a lot for the centrifugal force. In case you don't know what centrifugal force is, let's just say it's the reason you need to lean the bike over at high speeds, but hardly at all at low speeds (like a U turn in your driveway).

We cannot just steer a two wheeled vehicle around a corner, because we first of all have to make sure it leans into the turn. If we try to steer it WITHOUT leaning it, we will fall down to the OUTSIDE of the curve, due to centrifugal force. So how do we lean it into the curve? There are a couple of ways, one is to lean you body into the curve. This is fine at very low speeds, on lightweight machines (bicycles), but at high speeds, and sharp corners, on a heavy machine, you need help. That help comes from countersteering. With countersteering you can lean the bike over to any angle you wish, almost as fast as you can blink. Of course, the bike must be moving (the faster the better for countersteering), and you must be aware of the phenomenon, and secondly you must train the muscles of your wrist to do it without the aid of mnemonics like "push right to go right"

A motorcyclist is both steering and countersteering all the time. So imagine that the countersteering is overlayed on top of steering. Further, imagine you are in a high speed ring, circling to the right at 100 kph, leaned over at about 30 degrees to combat the centrifugal force, and everything is in perfect balance. But if you accidentally steer to the right more than necessary to get around the ring, the bike will stop leaning over. That is very bad, because now you are not balanced, and if you do not make it lean over again quickly at 30 degrees, it will continue to "fall" to the left. What can you do to bring the forces back into balance? One, you could reduce your speed, because you don't have to lean as much if you are going slower. Two, you could force the bike to lean to the right more by easing off your steering to the right. In other words, undo the mistake you just did when you accidentally steered too much to the right. As you steer less to the right, the bike will gradually lean more to the right, until it is in balance again, and you can resume the normal steering angle.

How can the rider tell when everything is in balance? I think that is almost unconscious also. It is actually just as hard to explain when you are driving in a straight line. How can you tell when the motorcycle is balanced in a straight line? Because it is not falling down. Same thing in a curve, except that you are leaning at 30 degrees to the horizon. But it still feels like you are not falling. I'm not sure I can explain that any better.

Here is my previous blog on countersteering.

http://lostmotorcycles.blogspot.com/2009/04/motorcycle-control-counter-steering.html

Here are a couple of videos, some of the ideas expressed are slightly different to mine, but the laws of physics would be the same.

http://www.youtube.com/watch?v=C848R9xWrjc

http://www.youtube.com/watch?v=B8IdTq3_3WI

Picture: That is a Kenworth. Not Peterbilt, not Western Star, not Freightliner. I know that because countersteering is now unconscious, so my conscious brain has time to deal with more important things.

3 comments:

  1. It doesn't work when riding (driving?) a combination either ... attempting to counter steer a sidecar rig can be interesting ... LOL!

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  2. That's a situation I had not thought of when the unconscious countersteering can be harmful. Now maybe if you drove the sidecar rig with your hands crossed to the opposite bars, it would cancel out and you could steer normally.

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  3. Countersteering, at slow speed, is more difficult to do on some motorcycles than others. It must be realized both direct steering and countersteeering are started from traveling staight. So practice them both from traveling straight. Depending on weight and its distribution, wheel base, degrees of rake but especially the amount of trail it may take more action to countersteer at slow speed. More trail makes direct steering easier when turning the front handlebars slowly in a direction. Traveling slowly and turning the front tire slowly a direction moves the motorcycle off to that side of the front tire's contact patch (because of trail). Gravity pulls down on the bike causing a lean to the turn side and the turn is made. It is impossible to trun a bike without leaning in that direction. That is slow speed direct steering. The way to countersteer at slow speed because there is less momentum available is to steer quickly and to more of a turn degree to cause a lean. The lesser available momentum pushes the front tire contact patch to move out from under the motorcycle to the turn side before gravity can cause a lean to the turn side. The motorcycle leans the opposite direction. This is followed the turning of the front tire to follow the lean. Many riders are afraid of turning the front tire quickly and to more of a turn degree at slow speed. It can be scary (because the motorcycle is less stable the slower it goes) until the rider gets comfortable with it. Practice slow speed countersteering on a bicycle first. Once you are comfortable countersteering at slow speed, you will find turns can be made sharper and quicker. Slow speed countersteering is a danger avoiding maneuver just as it is at higher speeds. In the photo of the motorcycle and the truck above, the motorcyclist is braking. That will make him and her to travel toward and possibly fall toward the truck. I would steer quickly toward the truck and accelerate at this point to lean away for a turn away from the inpending accident. Then I would countersteer toward the edge of the road and brake. That photo is a great example for why slow speed countersteering should be practiced extensively, while accelerating and braking so you know how to react. Theodore E Basler, author of Iron Horse Sense

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