Question: What Are The Physics Of Continuing A Counter-Steer During Th

[korn]

I got into a heated discussion with a work colleague earlier today (perhaps the only person who didn't laugh when the music came on in my video at

) who didn't think it possible that you could hold a counter-steer during a turn.

 

That is to say, while he believed in counter-steering to initiate the turn, he claimed that you would then have to at a minimum bring the handlebars back to neutral - if not actually turn slightly in the direction of the corner - in order to continue through the turn. My own "experimental evidence" was to the contrary, and I challenged him "as a scientist" to adapt his theories to evidence rather than insisting that his conception is correct.

 

So...

 

Can anyone explain WHY you might have the front wheel turned slightly away from the direction of your turn, and HOW that works?

[ktk_ace]

http://en.wikipedia.org/wiki/Countersteering

[korn]

Thanks ktk_ace, but... I don't see where that article explains what I remember experiencing - that my front wheel is pointed slight away from the corner/lean.

 

The text has (emphasis added):

"Once lean is achieved

 

As the desired angle is approached, the front wheel

must usually

be steered into the turn to maintain that angle or the bike will continue to lean with gravity, increasing in rate, until the side contacts the ground. This process often requires little or no physical effort, because the

geometry of the steering system of most bikes

is designed in such a way that the front wheel has a strong tendency to steer in the direction of a lean.

The actual torque the rider must apply to the handlebars to maintain a steady-state turn is a complex function of bike geometry, mass distribution, rider position, tire properties, turn radius, and forward speed. At low speeds, the steering torque necessary from the rider is usually negative, that is opposite the direction of the turn, even when the steering angle is in the direction of the turn. At higher speeds, the direction of the necessary input torque often becomes positive, that is in the same direction as the turn.

^[14]

^"

Yet for me in the Sears Point carousel, I recall NOT having the front wheel/bars rotating toward the turn. Is my memory faulty, or am I correct - in which case, WHY? What forces have the front wheel pointing away from the turn DURING THE TURN be correct?

[Lnewqban]

I got into a heated discussion with a work colleague earlier today........... who didn't think it possible that you could hold a counter-steer during a turn.

.............

Can anyone explain WHY you might have the front wheel turned slightly away from the direction of your turn, and HOW that works?

 

Your work colleague and you could be right and wrong at the same time, since you are riding different bikes.

 

According to how the geometry of the steering and tires (width and patch deformation) work for each during a turn, once the balance lean angle is reached, there are over-steering and under-steering motorcycles:

 

Read pages 111, 112 and 317:

 

http://books.google.....page&q&f=false

 

"Tires have a large influence over bike handling, especially on motorcycles. Tires influence bike dynamics in two distinct ways: finite crown radius and force generation. Increase the crown radius of the front tire has been shown to decrease the size or eliminate self stability. Increasing the crown radius of the rear tire has the opposite effect, but to a lesser degree.

 

Tire inflation pressures have also been found to be important variables in the behavior of a motorcycle at high speeds. Because the front and rear tires can have different slip angles due to weight distribution, tire properties, etc., bikes can experience understeer or oversteer. Of the two, understeer, in which the front wheel slides more than the rear wheel, is more dangerous since front wheel steering is critical for maintaining balance. When understeering, the steering angle must be greater, and when oversteering, the steering angle must be less than it would be if the slip angles were equal to maintain a given turn radius."

[noamkrief]

Your buddy is correct 100%. Counter steering makes changes to bike lean. While in a turn - BELIEVE ME - your handle bars are pointed in the direction of the turn. Keith Code in his movie explains and demonstrates this.

 

again - you turn the handlebars to the right to lean left, but once in a left hand turn leaning - your handle bars are turned to the left

 

I've heard alot of people take "countersteering" to the N'th degree like that.

 

The exception is oversteer conditions. So if you are in a turn and you are on the throttle hard and your rear tire is spinning, the handle bars will point away from the turn - or at least so it seams. In fact, they are still pointed towards the turn, just that the ass end kicked out and that's the natural correction that also happens automatically.

[Fajita Dave]

The front wheel is always following the direction you're traveling in. So if you're turning left, the front wheel is pointing left. As Lnewqban explained it does depend on the tire profile as well. One thing for certain the only possible way to be turning left and the wheel to be pointing right (off the line of travel) is if the front tire is sliding. If that happens it wont be sliding for long before you hit the ground.

 

When a motorcycle oversteers the frame is what moves around the steering stem. It looks like the handlebars are turned in the opposite direction of the corner. In reality the handlebars haven't moved at all, instead the frame rotated around them while the front wheel continues to follow the line being traveled.

[EricG]

As others have said, you will start the turn via counter steer, but one you've committed, the front tire will face into the turn. You can continue to counter steer, but that will tighten the turn radius. TofW2 shows this in lime the first 20 mins where count steering is discussed.

 

Now, having ridden a cruiser and now a sport (touring) bike, I can attest to the fact that they steer very differently. Counter steer on a chopper, on the other hand, has a much lower duration than a sport bike. My per theory is the narrow front tire and low center of gravity - together with the limited lean angle - require you to steer into the turn much earlier, and at slower speeds counter steering has limited application. At least compared to the sportier bikes we tend to ride.