gazedrop

Counter steering is how a 2 wheeled vehicle initiates a turn. Not very well understood still by a lot of people because it's also counter-intuitive. It's also why kids fall over when trying to ride a bike for the first w/o training wheels; they haven't yet "learned" counter steering via trial and error...

On a bicycle, it's hard to feel counter steering because it requires so little of it to get big results. So most riders steer by "learned instinct"...

Physics time! Your two rotating wheels are gyroscopes. Their gyroscopic mass resists being tilted or pivoted from their rotational plane. Up and down and side to side is fine, but they resist deflection. This is the main reason why a bicycle stays upright. To further demonstrate this, those of you who ride rollers know that it's easier to balance on them in a high gear with a high wheel speed than it is in a low granny gear and low wheel speed. More wheel speed equals more gyroscopic stability; i.e. the faster the gyroscope spins, the more it resists deflection.

However, when you DO deflect or pivot a gyroscope (such as when steering your bike), the gyro responds with a motion in different direction from that of the input. This is called precession.

When you turn the wheel to the left, the wheel instead leans to the right (provided that the wheel is spinning in a "forward" direction). Turn it to the right, and it leans to the left. This is precession in action. It's also the "Counter" in "Counter-steering".

The best part about this bit of theory is that there's an easy way demonstrate it to yourself. Take the front wheel off of your bike, hold it in both hands by the axle, and give it a good forward spin. Now, gently and "intuitively" turn the wheel to the right... What happened? It leaned to the left! (Please try this! It's far more telling than just listening to me!)

Rate and degree of precession is also dependant upon rate and degree of input. In other words, steer hard and fast and it'll lean hard and fast. Get your wheel spinning again. This time, turn it to the right again, but do so quickly and firmly. Wow, it leans over pretty quick, huh?

As long as you have that greasy axle in hands, there's two more things to try...

First, try to steer it to the right AND lean it to the right at the same time. Get's pretty unruly, huh? That's we do as kids learning to ride, right before we pick ourselves up off of the ground...

And second, just to drive the point of precession home, give the wheel a good backwards spin and go through the above motions. Now you'll see that it does just the opposite as before.

I have one more way for you to prove to yourselves that countersteering is what initiates a turn (and, by the way, straightens the bike out of a turn...)

Put your wheel back on the bike and go for ride down the street. You don't need to go very fast. Stop pedaling and glide to help take leaning your body out of the equation. (If you ride a fixie, don't worry, this experiment will still work.)

Now place your domiinant hand on the stem and take the other hand off of the bar. (This will prevent your years of "learned instincts" from taking over and coloring this test.) Turn the stem to the left. The bike tried to go right awfully quick, didn't it? PLEASE be careful doing this! It takes suprising little effort for the bike to steer from under you!

Now that your getting a feel for this, with your hand still only holding the stem, try progressively sharper steering inputs. Do this just to get a feel for counter steering and to imprint it into your mind. Now place your hands back on the handlebars and practice it. You'll feel it even less because you have more leverage on the bars, and with this leverage your counter steering input doesn't need to be as strong. But I'll bet you're now aware of it nonetheless...

"But when I look down at my bars and wheel in the middle of a turn, I can SEE that they're pointed in the same direction of the turn, and not counter steered!"

Yup. Like I said, counter steering is how a two-wheeled vehicle initiates a turn. But yes, they do track through a turn the way you'd expect.

When the wheel leans into the turn (a result of the counter steering input) it partially neutralizes the original input. That's where the turning energy goes. But since the act of leaning equates to another input on the wheel, it precesses again. This time it does so into the direction of the turn.

Take that wheel off your bike again. Get it spinning in a forward direction. This time, don't steer it. Instead, lean it to right. It steers right.

Have fun with this! And learn to trust it without doubt. Many accidents can be avoided by reacting with counter steering (like while in the middle of a peloton).

If you don't respond with counter steering in a panic situation, what usually happens is this: Riders, bikes, debris, etc. in front of you. You see an escape path to the right. Wanting really, really bad to go to the right, you lean hard to right while also trying muscle the bars to the right. Input #1 tries to take you right. Input #2 tries to take you to the left! Result: You go either straight, or lord knows where and with little control...

Give it a try!

-Erik