Countersteer - Push-me Pull-me?

[ElevenFifty]

Had an interesting ride down the BRP last week. I've never done a track day or performance riding school and tend to be on the conservative side regarding speed and sight lines. As a lifelong sailor of small boats, one of my favorite homilies is "The bottom of the ocean is littered with the bones of optimists". When you are responsible for someone else's safety then that concern is the primary one and about half my riding is 2-up so I'm a bit of a slow poke.

 

Solo on the bike, I do okay. 'Slow in-Fast out' ... 'Kiss the mirrors' ... 'late apex' ... and so on. I actively work on my skills and on some days ride quite smoothly.

 

Set up for the turn, keep revs high to maximize speed control without braking, shift weight to the inside, maximize the sight lines, wait for the apex, active countersteer with force on the inside grip ... On lousy days, all this is like some kind of mantra that I repeat over and over while doing most of it wrong. Zen sort of problem ... over thinking everything.

 

Last Wednesday, riding the sweepers on the BRP and having way too much fun, I did something different. In one left hand sweeper, just for the fun of it, I sort of 'hung' on the high side grip. Instead of taking by weight on the inside hand and applying pressure (countersteer) to the inside grip, I was just applying very light force on the inside grip to modulate the force of my fully extended right arm that was taking the weight of my body and 'pulling' me through the turns.

 

I found that my input was just about effortless and I was riding much more smoothly. I'm very right hand dominant and found that the natural feel of left hand turns was not quite so natural when turning right so I started working on that.

 

I have a hunch that the 'correct' way to do all this is better balanced ... neither pushing nor pulling the bike through the turns. But I have to say that just hanging off the high side seems to keep my body weight well to the inside of the turn and requires minimal and very light input from the inside hand.

 

 

[Mister Tee]

You shouldn't have to force or apply pressure to the bars through turns if your body position is correct. I used to demonstrate one-handed full lean turns to my track students.

[racer7]

True enough but ignores the issue that for some, the bar pressure one way or the other is also a key feedback to their control. How much pressure on either bar side depends on a lot of things from tires and chassis to speed and relative use of brakes or not. A very common phenom is that the amount of weight shifting that it takes can change a lot as tread wears, especially if it "squares up" much as it wears out.

 

There is a happy spot with light controls for most riders. One shouldn't have the feeling of ever having to fight a bike in a corner in normal riding- that would be a sign that a large improvement in technique is required before the rider gets hurt- there are plenty of folks out there who simply run off curves at low speeds because when you cut through everything, they're got low /no skills and get bit by one of what Keith Code calls SR's.

Beginners often fail to move around enough on the bike and end up with excessive steering effort as a result as you recognize in teaching about it.

 

Racing go karts make pretty good trainers for riding. It takes a lot of crawling around the kart to get optimum traction and therefore turning and acceleration- its extremely physical- and what's leaned there will transfer to bikes re weigt transfer importance. (Not the steering however; karts are brutal on hands and require gloves if you want to keep your skin) One can start kids on it early, just like on small dirt bikes, and racing rentals against friends can be hoot, should you have a track nearby..

[Joe Frickin' Friday]

You shouldn't have to force or apply pressure to the bars through turns if your body position is correct. I used to demonstrate one-handed full lean turns to my track students.

 

For any given turn there is indeed a body position that will result in neutral steering, but I don't believe this is neessarily the "correct" body position. I tend to prefer leaning off well beyond this position, such that even after I am fully in the turn, I have to apply continuous pressure to the outside grip to keep the bike from spiraling into a tighter and tighter turn; the benefit of doing so is that the bike itself stays closer to vertical, resulting in better suspension action and greater ground clearance for the low parts (e.g. footpegs).

[Mister Tee]

You shouldn't have to force or apply pressure to the bars through turns if your body position is correct. I used to demonstrate one-handed full lean turns to my track students.

 

For any given turn there is indeed a body position that will result in neutral steering, but I don't believe this is neessarily the "correct" body position. I tend to prefer leaning off well beyond this position, such that even after I am fully in the turn, I have to apply continuous pressure to the outside grip to keep the bike from spiraling into a tighter and tighter turn; the benefit of doing so is that the bike itself stays closer to vertical, resulting in better suspension action and greater ground clearance for the low parts (e.g. footpegs).

 

Okay but those are two separate aspects of cornering. Of course you want to be leaned in such a way that you maximize your bike's upright position, but any force you put on the bars results in a scrubbing of the front tire, and subsequent traction loss, so you don't want to have to put a significant amount of force on the bars either way in order to maintain your line.

[Ken H.]

Of course you want to be leaned in such a way that you maximize your bike's upright position, but any force you put on the bars results in a scrubbing of the front tire, and subsequent traction loss, so you don't want to have to put a significant amount of force on the bars either way in order to maintain your line.

Yes, that is also my understanding/approach. A neutral balance body position, light if any grip pressure, on either one, will allow the bike, all things else being constant (which of course they rarely are), to continue in an unassisted arc indefinitely. Much like a banking airplane does. This we know.

 

However any ongoing bar input once the arc is initiated, e.g. forcing it more up right with outside grip push pressure, actually in and of itself is reducing available traction due to, as you mentioned, increased ongoing front tyre scrub. The better approach is to allow the bike to establish a more upright but self-sustaining arc by moving more mass (yourself and where applicable pillion) more inside.

 

Now I certainly use what Mitch is describing when setting up for a pending/upcoming curve. Move myself (and Donna) inside while still in a straight line, holding the bike going straight with opposite grip push pressure, and then once the apex is reached – release, and as necessary apply counter-steer inside grip push pressure, to allow the bike to drop into a neutral arc through the turn.

 

If I get everything perfectly right. Which I rarely do.

 

Side note - We often talk (correctly) about counter-steering in terms of pushing on the grip in the direction you want to go/turn. But we all should not forget that pulling on the other one is exactly the same thing. In some critical situations where a massive sudden turn is what’s going to save your bacon, and you need all the strength you can muster, it’s worth remembering you can use both arms to force that puppy over.

 

It’s a fun and learning exercise to go ride slaloms with one hand, alternating pushing and pulling on a singe grip. (Of course a throttle lock or cruise is needed when doing this with your left hand.)

[Joe Frickin' Friday]

Of course you want to be leaned in such a way that you maximize your bike's upright position, but any force you put on the bars results in a scrubbing of the front tire, and subsequent traction loss, so you don't want to have to put a significant amount of force on the bars either way in order to maintain your line.

 

However any ongoing bar input once the arc is initiated, e.g. forcing it more up right with outside grip push pressure, actually in and of itself is reducing available traction due to, as you mentioned, increased ongoing front tyre scrub.

 

I'm pretty sure this ain't true. Lemme illustrate with a situation in which the forces might be more obvious.

 

First, consider a fellow on a bicycle traveling in a straight line at a steady speed. I'm going with a bicycle here because it only weighs 10-20 pounds, and so when the rider leans off, the bicycle really leans the other way. Now, instead of traveling through a turn, let us imagine the rider is traveling in a straight line down the road. He hangs his body off to the left, and the bicycle itself leans way over to the right, with the net result that his center of mass stays centered between the two tires' contact patches. With zero steering input, the bicycle's steering geometry would automatically turn the bars to the right, steering the contact patchs out from under him and sending him into a left turn. So before this happens, the rider grabs the bars and holds them straight, with the result that the bike continues straight down the road. Can you see that there's no traction force required from the tires in this scenario? You could even do this in the snow (i.e. under minimal traction conditions), and you would not induce any tire slip at all.

 

If you don't believe me, wait a few months for an inch of fresh snow, then get out your bicycle and try it. This works well because you can do this experiment at low speeds in a safe area, so if you fall, you won't get seriously hurt. But trust me, as long as you're traveling in a straight line you won't fall, unless you do something dumb with the brakes.

 

Finally, one more logic test. Suppose that you're right, and that additional lateral forces are present at the front tire's contact patch when one navigates through a turn as I described (body leaned far to inside, outside hand applies forward pressure on the bar to prevent spiraling into a tighter turn). That additional lateral force at the front tire's contact patch would have to manifest as an increased lateral acceleration of the whole bike-and-rider assembly. Afterall, F = m * a. If you're right, that effect would be unavoidable. In fact, things would get crazy rather quickly: greater lateral acceleration at the front wheel, but fixed lateral acceleration at the rear wheel, means the bike's nose would veer inward toward the center-of-curvature of the turn. Note that nothing like this happens; that's a pretty sure sign that there's no extra scrubbing force when one is leaned off and simultaneously exerting a steering input to hold a constant-radius turn.

 

 

[Dave_zoom_zoom]

Hi Mitch

 

Well there you go again! You can really screw up a really great theory with all that damn logic.

 

Dave

[Ken H.]

Hummm… still thinking about this… Here’s where I get questioning your theory – If you are, let’s call it ‘overhanging’ for lack of a better term, in a curve, by your own admission and I agree, left to its own path, the bike would spiral in to itself (and go down) in a decreasing radius inside loop in short order. Agreed?

 

So to counter act it from doing just that you push on the outside bar, keeping the front wheel in the track of the arc you want (your desired line). The front tyre is being forced (by you) to follow a path of a lesser angle than had it been allowed to track unimpeded. I contend that ‘delta of path’ has to a cause some increase in slip, scrub, as you are forcing it off its dynamically normal path.

 

In a normal neutral balanced cornering scrubbing still there even, but minimized. It’s the arc where the tyre is consuming the least amount (notice I didn’t say no) of our total traction budget. In standard turning, If we aren’t neutral, but are doing normal counter-steering (pushing on the inside grip), it’s consuming more of the traction budget as we as the rider are forcing the tyre to track inside its normal arc for the current balance of the mass and bike. We’re using up more of our finite amount of available traction in forcing the tyre inside. It’s the whole point of why we move mass inside to start with, so less of our traction budget is consumed in forcing the tyre’s path. It works up to the point where all the available traction is consumed trying to make the tyre follow a tighter than neutral arc and we low-side.

 

Your scenario is no different, just in the opposite direction. The tyre, for the current balance, wants to track inside (toward an eventual death spiral) but you are forcing it to track outside, just the same consuming more of the total traction budget than had the balance been neutral.

 

Because the traction between the road surface and a tyre’s surface is never 100% there is always some slip going on (even when going straight actually). Whenever we increase the demand on the tryre to use some of the traction budget, regardless of direction, the slip/scrub increases also. Thus as we countersteer in either scenario to tighten an arc or to widen it vs.the bike's neutral arc - tyre scrubbing goes up.

 

[Joe Frickin' Friday]

In a normal neutral balanced cornering scrubbing still there even, but minimized.

 

My contention is that if your tires are following a constant-radius arc through the turn, and you are traveling at a constant speed (and therefore at a constant lean angle as measured from the contact patches to the combined center-of-mass of rider + bike), then the traction forces at the tires' contact patches are determined entirely by your speed and by the radius of the arc along which your tires travel.

 

If there's some additional traction force at the contact patches because the rider is leaning off and applying steering force (not movement) to stop the bike from leaning farther and keep the tires following that same arc, then you have to explain why the bike doesn't spiral out of control as I described in my previous post.

 

 

[Ken H.]

Okay, let’s think about it this way for a second… If you are traveling in a straight line, but hanging way off to one side of the bike (assume no cross wind factor or anything like that for now) to continue in a straight line you would have to push on the grip opposite of your hang off, agreed? It would be impossible to do such a maneuver hands free, the bike’s natural balance for straight travel has been upset. As you are pushing on the opposite grip the tyre’s contact patch has moved somewhat to the same side as your hang off, also agreed? Also in the process of moving to one side, because of the triple tree’s geometry and rake of the fork, it has also turned slightly toward the pushed grip. Thus it is now side slipping, scrubbing its way down the road, yes?

 

I visualize it’s no different so when you’re do the same thing during a curve. The tyre is side slipping.

 

ISFA you question as to why (when you executing your maneuver / riding style) you don’t spiral out of control, that’s because, just like in any conventional counter-steered turn, you have not yet fully consumed your traction budget. Normal traction required + the additional demand you are adding by opposite steering is < total available. If you carried the maneuver past the limit you would indeed spiral inward and down. It’s the same reason so many riders get away with lousily body position and excessive counter-steer to continue the turn – their tyre to road surface grip is good enough, that the total traction budget is high enough, that they don’t exceed it. Until of course they do and low-side.

 

[Joe Frickin' Friday]

Okay, lets think about it this way for a second If you are traveling in a straight line, but hanging way off to one side of the bike (assume no cross wind factor or anything like that for now) to continue in a straight line you would have to push on the grip opposite of your hang off, agreed?

 

We need to define steering "input" very carefully here.

 

Hanging your body to the left, continuing in a straight path, yes, you would apply a forward force to the right handlebar - but this is to prevent the bike's steering geometry from automatically turning the bars to the right at all (i.e. to prevent it from automatically countersteering to initiate a left turn). So you apply that forward force to keep the bars pointed dead straight ahead, i.e. zero steering displacement.

 

It would be impossible to do such a maneuver hands free, the bikes natural balance for straight travel has been upset. As you are pushing on the opposite grip the tyres contact patch has moved somewhat to the same side as your hang off, also agreed? Also in the process of moving to one side, because of the triple trees geometry and rake of the fork, it has also turned slightly toward the pushed grip. Thus it is now side slipping, scrubbing its way down the road, yes?

 

Again, for traveling straight down the road, there must be no steering displacement; when leaning off to one side, a force input from the rider is required to prevent the steering from moving on its own.

 

ISFA you question as to why (when you executing your maneuver / riding style) you dont spiral out of control, thats because, just like in any conventional counter-steered turn, you have not yet fully consumed your traction budget.

 

traction budget doesn't factor into this. Bike+rider is a mass that responds to externally applied forces in accordance with well-established laws of physics. A certain amount of lateral traction force is required to hold a constant-radius turn. Any additional lateral traction force will cause this mass to deviate from that path. So when you are following a constant-radius turn at a constant speed, the traction force at the tires must be the same, regardless of whether or not you are hanging your body off to one side.

[FLrider]

 

I tend to prefer leaning off well beyond this position, such that even after I am fully in the turn, I have to apply continuous pressure to the outside grip to keep the bike from spiraling into a tighter and tighter turn; the benefit of doing so is that the bike itself stays closer to vertical, resulting in better suspension action and greater ground clearance for the low parts (e.g. footpegs).

 

After years of (apparently) not leaning enough and using pressure on the inside grip to get the turn in I wanted, I started doing what you described above. I think my turning has improved. Right or Wrong, it just feels better.

[tallman]

Mitch passed me on the Cherohala going the opposite direction.

He got to the end and turned around passed me going my direction.

It works.

 

How about we include how big our feet are and how much pressure we put on which peg?

 

 

Doesn't pushing on a bar work in tandem with knees and feet on pegs wrt "steering inputs"?

Just asking 'cause I ride slowly no matter what.

[CoarsegoldKid]

My contention is feet on the peg makes no difference on our bike's ergonomics. On a bike with raised rear-sets and clip-ons the foot pushes rearward providing a point of purchase to push opposite the steering input. But on our bikes the foot is pushing down. Clamping the tank with the outside knee provides an "at one" feeling with the bike so you don't fall off. Not all road racers do that however. I've witnessed one or two actually fall off on the inside lean.

On a dirt bike while standing shifting weight down on the inside peg assists greatly in turning the bike.

 

Pull or push accomplishes the same. Lee Parks says to do one not both. I do both on occasion. Then again sometimes I pull and sometimes I push. I believe front tire wear comes into play requiring extra effort. Pulling has aggravated right hand issues for me. Maybe it's arthritis setting in?

 

[tallman]

Joe,

Understand.

But I wonder if we measured the force applied to pegs, before and during the turn/exit, compared to before and plotted it with the bar input if there is a corellation or discirnible data.

Could be there is no change in foot pressure.

I'm merely interested...

[Ken H.]

Well I still don’t understand how we can apply any force in any direction to cause the front tyre to track other than where it naturally wants to for the bike’s balance of the moment, and not have that force that is acting on the tyre to road contact patch (even if to put it back on a straight track) consume some amount of the available traction budget and thus introduce some amount of scrub. But I’ll let the subject go...

[EddyQ]

If there's some additional traction force at the contact patches because the rider is leaning off and applying steering force (not movement) to stop the bike from leaning farther and keep the tires following that same arc, then you have to explain why the bike doesn't spiral out of control as I described in my previous post.

 

I think a bicycle going straight down the road with a rider hanging way off to the left, applying force to the handlebars will experience less traction than if he was not hanging off. A wheel with finite width and radius to the tire cross section will want to turn to the right if tilted to the right. If it is forced to go straight, then sections of the contact patch are skidding.

Hence the tire has lost traction.

 

Only if the tire has has zero width will radius be constant when the wheel is tilted.

[Quinn]

Okay, now I'm getting confused. I would assume that if I lean my weight off the left side, I'm smushing (technical term for compressing) the left side of the tire and in effect moving the contact patch over that way. The new contact patch is of a smaller diameter toward its left edge and therefore the bike wants to go left. To conteract this, I purposely upset the bike to the right by countersteering and the net result is that the bike keeps going straight. Since I'm having to force the bike back to the right with steering imput, looks like I'd be scrubbing rubber off the tire with sideways pressure to keep it upright. Sort of like a smooth crab walk down the road. That would be using traction, right?

 

My simplistic mind says that it is the conical shape of the contact patch that creates the radius of the turn. If weight is centered on the bike, then it's all in the lean angle. If hanging weight off one side, then the lean angle doesn't have to be as great to achieve the same degree of conicality (made up scientific term).

 

-----

 

 

[Joe Frickin' Friday]

I think a bicycle going straight down the road with a rider hanging way off to the left, applying force to the handlebars will experience less traction than if he was not hanging off. A wheel with finite width and radius to the tire cross section will want to turn to the right if tilted to the right.

 

Agreed, the front wheel does indeed want to turn to the right in this scenario. However, wheel width will have only a very small effect because of rolling resistance and braking inputs; we are assuming no braking here, and rolling resistance is neglibily small.

 

The front wheel wants to turn right almost entirely because of the steering geometry. The angle of the steer tube (and other parameters like rake and trail) are set up so that the front tire's contact patch is behind the steering axis, and the combined effect of the bike's weight plus lateral traction forces tends to cause the handlebars to move in such a manner as to make the bike "get its feet back under itself," so to speak, when it deviates from a stable straight course. This is what makes it possible to ride a bicycle or motorcycle hands-free without crashing out in just a couple of seconds.

 

(in the case of a bicycle traveling straight ahead but with the rider leaning off, there is no lateral traction force present - there can't be, or we wouldn't be traveling in a straight line - so it's only the road pushing straight up on the contact patch that causes the handlebars to want to turn.)

 

If you fabricate a bike with a 90-degree head angle and zero rake/trail, the contact patch will be intersected by the steering axis, and there will be no tendency for self-correction; the bars will not try to turn right when you lean off to the left side, and you'll be able to cruise straight down the road with pretty much zero rider force on the handlebars. Would you at least agree that a non-self-correcting bike such as this does not have any traction budget consumed when hanging off to the left while traveling straight?

 

If it is forced to go straight, then sections of the contact patch are skidding.

Hence the tire has lost traction.

 

The rider's fight (i.e. his steering effort) is against the self-correcting nature of the steering geometry, not against the tire's traction. The contact patches won't want to go to the right until the handlebars are allowed to turn to the right. If you don't let the handlebars turn right, then the contact patch doesn't want to go right, and so it continues to go straight down the road without a fight. On the non-self-correcting bike described above, the steering geometry keeps the front wheel pointed straight ahead; on a real, rideable bike, the rider does it. The tires don't know the difference between the two bikes; they only know that they're pointed straight ahead.

 

Okay, now I'm getting confused. I would assume that if I lean my weight off the left side, I'm smushing (technical term for compressing) the left side of the tire and in effect moving the contact patch over that way.

 

If you lean your body to the left, the bike has to lean to the right so that the combined center of mass is still centered over the bike (assuming we are traveling straight down the road). Since the bike is leaned to the right, the tires' contact patches are now somewhere between the tires' centerlines and their treads' right edges.

 

My simplistic mind says that it is the conical shape of the contact patch that creates the radius of the turn.

 

A turn happens because the axes of the front and rear wheels aren't parallel. On a bicycle, you can lean way off to the left while turning left, and the bicycle itself can be perfectly vertical through the entire turn. This shows that the conicality of the lateral areas of the tread is not particularly a factor.

 

If the bicycle is vertical, then the center of the turn is located at the point in space where the front and rear wheels' axes intersect; this sketch of car steering geometry may sort of help visualize what I'm saying.

 

If the bike is leaned over, then it's slightly more complicated:

 

1. For each wheel of the leaning motorcycle, visualize a plane that contains that wheel's axis and its contact patch. Each of these two planes (one for the front wheel, one for the rear wheel) is vertical.

 

2. Extend those two planes toward the inside of the turn; they will form a vertical line where they intersect. That line (or the point where it intersects the pavement) is the center from which the radius of your turn is measured.

[FLrider]

.....remind me to never ask Joe what time it is......

[Dave_zoom_zoom]

.....remind me to never ask Joe what time it is......

 

-1

 

I DON'T AGREE! He is one of my heroes.

[Bernie]

I fully agree with Mitch. Today several times I encountered big dips or potholes on tight curves, which could have spelled disasters, if the bike would have been leaned way over. But by leaning my body off the inside of the bike, the bike travelled through the hazard in an more upright position and the suspension was able to absorb the bumps without the tires losing traction.

It is not just for outright speed, but it is a safety issue.

[FLrider]

.....remind me to never ask Joe what time it is......

 

-1

 

I DON'T AGREE! He is one of my heroes.

 

I agree, he is very bright. You obviously missed my point.....

[Dave_zoom_zoom]

.....remind me to never ask Joe what time it is......

 

-1

 

I DON'T AGREE! He is one of my heroes.

 

I agree, he is very bright. You obviously missed my point.....

 

Sorry

[Joe Frickin' Friday]

I agree, he is very bright. You obviously missed my point.....

 

...which is that I am, on occasion, extremely tedious.

[Matts_12GS]

I agree, he is very bright. You obviously missed my point.....

 

...which is that I am, on occasion, extremely tedious.

 

Tedious at best.

 

Sometimes just verbose!

[Glenn Reed]

I agree, he is very bright. You obviously missed my point.....

 

...which is that I am, on occasion, extremely tedious.

 

You see, this is a perfect example. You couldn't go with just tedious, you had to amplify by making it extremely tedious.

Sorry I missed out on seeing you at the FART, looks like it was a great time.

[FLrider]

I agree, he is very bright. You obviously missed my point.....

 

...which is that I am, on occasion, extremely tedious.

 

I prefer the word ....accurate, detailed, ....like a swiss watch...