I teach the concept of counter steering in motorcycle safety classes. My response is that "It's Magic. Push right and turn right. I know you don't believe me but go out there and try it. It works." I've seen contradictory explanations for it using laws of physics. The best answer I've come up with is that It's Magic.

reggiedog,

Stand beside your bike and hold it upright. Now start to lay your bike over on its side but watch the front wheel as you do this.

If your headset is not over tightened to prevent your front wheel from turning freely, you will discover that your front wheel will first begin to "turn" in the opposite direction from the side on which you are trying to lay your bike down on. This phenomenon is counter steer.

Counter steer is not leaning your bike over. Counter steer is steering away from the turn or intended direction. Hence the term, counter which in this instance means opposite.

This technique also assists the rider to properly position his body weight to help negotiate the turn rather than struggle to get in the proper position without counter steering.

This is a significant part of the difference in descending skills between Armstrong and Ullrich. Armstrong is a very accomplished counter steerer and Ullrich is a very timid, uncomfortable counter steerer. But Ullrich has made some significant progress in recent years with his descending skills and this should give you confidence that you too can improve your cornering and descneding by learning and practicing counter steering.

---

Ben Cline


Better to aspire to Greatness and fail, than to not challenge one's self at all, and succeed.

When you turn left, not only are you leaning, but you're actually turning your bars a bit to the left too. So I don't think your understanding of counter-steer is appropriate.

Think of when you start a turn. If you're going to turn right, you'll actually initiate the turn by turning your bars to the left, this will cause you to start to lean to the right, then you'll follow your lean with your bars and turn them right too. So to turn right, you start by counter-steering to the left. Think of riding VERY close to the edge of the road or a curb. It's pretty difficult to turn away from the edge/curb with out going over/hitting it. This is b/c you can't counter-steer to initiate your turn away from it. (I think Dan's prolly got an article talking about this somewhere...)

Pooks nails it.

Ride through some small puddles and, after you leave the puddle, make a slight turn. Go back and look at the tracks. You will find that you are counter steering without even knowing it. When you turn right, your front wheel will first move slightly to the left until you have leaned over. The curve of the wheel then bites and you will turn right.

Counter steering is only involved at the start of a turn.

Turns on a bike are, like turns while running, initiated by moving the support position out from beneath your center of gravity, in the opposite direction of the intended turn.. To turn right, you need to move the contact patches of your tires to the left of your body. You don't do this by leaning, you do this by turning the bicycle to the left. You are now unbalanced, and you fall to the right.

This is all second-nature.

---

----------------------------------
"Go yell at an M&M"

Having actually gone through a motorcycle course and clearly tried to start a technical explanation in my post (and yes ridden a bike a bunch) it seem that Wants2 and Pooks are completely off the mark:

I don't think you turn a bike - at any appreciable speed - by using your handlebars. Rather you turn by leaning, which requires as counter steer to modulate. (my question is about the modulation, I guess)

Hence the ideas that either Ulrich is a "poor countersteerer" or that you start a turn by turning you handlebars towards the turn (try that at 20 mph ;-) seems off.

simplysean's idea of magic must be at work for you two...

i agree with sean, that it is magic.

the most dramatic way i know to illustrate the phenomenon is this:

get up a moderate amount of speed in a large smooth parking lot, and then iniate a swooping, leaning, carving turn - let us say to the right. in the midst of that carve, push with gradual but firm force against the left handlebar. notice how doing so causes the bike ( or motorcycle) to magically rise up from the right turn and flop over into a left turn (!!!) on a motorcycle this rise and flop is almost alarming when first experienced.

notice also that the more you think about how it works, the more you are confused by it. that is because, as sean sez, it is magic.

Go do my puddle exercise described above.

Rest assured, you, too, are counter steering, but you don't know it.

You are right that you turn by leaning, but the counter steering initiates the lean.

True if you assume a constant radius turn. If however, you get halfway through a turn and realize you need to make the turn tighter, counter steering will be involved to initiate the new smaller radius turn.

Quote, "Hence the ideas that either Ulrich is a "poor countersteerer" or that you start a turn by turning you handlebars towards the turn (try that at 20 mph ;-) seems off."



reggiedog,

I'll wait for you to catch up at the bottom of the descent. We can then talk about this some more.

---

Ben Cline


Better to aspire to Greatness and fail, than to not challenge one's self at all, and succeed.

So ken, when you run, you start a right hand turn by taking a step to the left?

I never tested that in my puddle tests, but it makes perfect sense.

First, I'm not sure what you mean by "modulate" in the first sentence. Do you mean how quick of a turn you make? Or how you keep a constant radius turn.

Second, the second part you wrote seems off because it is. You do not turn the handlebars in the direction of the turn at speed, above approx 10-15 mph. At low speeds, you do turn the handlebars in the direction you want to turn. At speed, you initiate a right hand turn by pushing on the right handlebar, effectively turning your front wheel slightly to the left. This initiates the lean and causes the right hand turn.

yeah, it really is "magic" to see how "local experts" don't understand the mechanics of biking. It is really a cool education when you do some of that slow speed stuff in the safety course!

by "modulate" I am thinking that you have to reduce the turning effect of the lean; mitigate that fact that the lean will cause you to turn sharper than you want to.

If you are riding in a straight line at any reasonable speed, are you not perfectly centered over your contact points? What is it that you are pushing against to initiate this alleged lean? Are you somehow pushing sideways against the ground?

Here's the wreck.bikes FAQ entry on countersteering:

"Countersteer is a popular subject for people who belatedly discover or
rediscover how to balance. What is not apparent, is that two wheeled
vehicles can be controlled ONLY by countersteer, there is no other
way. Unlike a car, a bicycle cannot be diverted from a straight path
by steering the wheel to one side. The bicycle must first be leaned
in that direction by steering it ever so slightly the other way. This
is the means by which a broomstick is balanced on the palm of the hand
or a bicycle on the road. The point of support is moved beneath the
mass, in line with the combined forces of gravity and cornering, and
it requires steering, counter and otherwise. It is so obvious that
runners never mention it, although football, basketball, and ice
hockey players conspicuously do it."

Just for background, this entry was written by someone who appeared in a bicycle tire ad leaning his bike over more than 45 degrees from vertical (I found it! http://www.sheldonbrown.com/brandt/). Don't try this at home.

---

----------------------------------
"Go yell at an M&M"

All you gotta do to understand this magic of physics, short of taking a junior level class of physics in college, is take your wheel off your bike, give it a good spin, and then try to slowly "turn" it in one direction. You will feel the force, young Luke...

---

FIST Certified Fitter
Salt Lake City, Utah

I'm at work right now, so I can't test it, but I'm willing to bet cash dollars that a turn to the right begins by placing either foot further to the left than normally placed to run straight ahead. Place the left foot further out, or place the right foot to the left of your center of gravity. How else would one do it?

---

----------------------------------
"Go yell at an M&M"

I dont think you can compare counter steering to turning while running. I agree there is a push off when running to change direction. There is no push off in cycling.

The purpose of both is to move the contact points (tires for cycling, feet for running) out from below the center of gravity. This initiates a lean in the desired direction. Try turning while running without leaning.

---

----------------------------------
"Go yell at an M&M"

Hmm, this is why I should have kept with my answer, "It's Magic". ;)

I believe your question is bringing into the discussion other principles of physics. Much of the explanation of counter steering is based on a constant speed, easy for a motorcycle. On a bike, unless you keep pedaling, not always smart, a turn introduces deceleration. This additional force requires either a modulation in lean to retain a constant radius turn or your turn will become tighter. Once you have constant force on the haldlebars ina turn, AT A CONSTANT SPEED, you will remain in a constant radius turn. If the bike accelerates or decelerates, the previous constant force on the handlebars will result in a different radius turn. I think this is what you are modulating against when you say the turn becomes sharper.

Here's a nice article from the physics dept. at UC Berkeley that explains it.

http://socrates.berkeley.edu/...les/SteerBikeAJP.PDF

Here's a summary:

Many factors interact in a complicated way to determine how much torque you need to apply to the handlebars, and how the torques scale with velocity. If you look at Equation 1 of my paper, you see that

(Gyroscopic Torque) + (Moment of inertia of wheel around steering axis times acceleration of the steering angle)
= (Applied torque on handlebars) - (Trail-steering)-(Castering)

The sign of the gyroscopic term always tends to turn the wheel in the required final direction. Since you are countersteering, the torque that you need to apply works against the gyroscopic term. Thus the bigger the gyroscopic term, the harder you have to countersteer to compensate. And the gyroscopic term increases linearly with velocity, so the faster you go, the harder you have to countersteer.

But this is only a small part of the answer; the two last terms in the equation are much bigger than the gyro term. Both depend on the velocity like v^2 (this is explicit for the castering term, and comes from the fact that the final lean angle lambda goes like v^2 for the trail-steering term.) At the very beginning of the turn, when you need to turn the handlebars the wrong way, the castering term resists this, so the countersteering has to increase...like v^2. Later on, as the wheel eventually turns in the right way, the castering term helps out, but the trail-steering term almost cancels the castering term and there is no simple way to predict which "wins."

Thus
1) You've got to fight the gyroscopic term, which increases like v.
2) Initially you've got to fight the castering term, which goes like v^2. Eventually the castering term helps, but by then
3) You've got to fight the trail term, which effectively goes like v^2 because of its dependence on angle.

Hope this helps

excellent reference. ( I loved the shaving your legs myth).

But there is surely some turning effect of sidewall/arc of the wheel in a turn? And can't you start a lean without turning the handlebars?

Well, everyone else has given it a shot, so here is my explanation. Countersteering is a function of the wheel being a gyroscope. And as a gyroscope, it reacts strangely when forces are applied to it. Specifically, when a force is applied to a gyroscope, that force is felt 90 degrees in the direction of rotation. Sooooo, when you turn the handlebars of your bike to the right, you could say that you are applying a force to the right on the front part of the wheel, and a force to the left on the back part of the wheel. Imagine holding the wheel by the tire with one hand on the front and one hand on the rear of the wheel (like holding your steering wheel at 3 o'clock and 9 o'clock). In order to turn the wheel to the right, you would have apply a rightward force to the front and a leftward force to the rear. That applied force, because the tire is a gyroscope, is felt 90 degrees later in the direction of rotation. The rightward force that was applied to the front of the tire is now felt at the bottom of the tire, where it is touching the pavement. Because of the friction with the pavement, this force doesn't do much, but the other force, the one to the left, is now being felt on the top of the wheel. This force is what causes the bike to lean to the left. One way to easily see this effect is to remove your front wheel, hold it by the skewer, and spin it (pay attention to which direction you spin it), and then turn the wheel (apply a force to it). You will find that the wheel wants to turn in a different direction than you are trying to turn it.

Or maybe it is magic!

OK, so how does that sound?

And here it is ...

Where we quote

"... you need to understand how a bike is steered, and how a tri bike is steered. You don’t steer a bike—any bike—by turning in the direction you want to go. You first countersteer, that is, you turn the wheel in the opposite direction. You may not realize this until you’re next to a curb, or next to another rider, from which you must veer away. You then realize you have no room to maneuver, and that’s because the first maneuver is to veer away from the desired direction in order to get your center of gravity between the bike and the direction you want to go. Then you can lean into the turn."

Glad to help.

---

"What's your claim?" - Ben Gravy
"Your best work is the work you're excited about" - Rick Rubin