How much of this is true

[hang man]

In the article it claims that if you are riding at speeds and want to turn left and attempt to push your handle bars to the left you'll be turning right and vice versa , i mean WTF is that all about ?

http://auto.howstuffworks.com/motorcycle4.htm 

[happycommuter]

Absolutely true.  Same thing on a bicycle at high enough speed.

A good tip for performance cornering (courtesy of Lee Parks) is to push with the inside hand, and have the outside arm totally slack. 
 
Skip past the first third of banter and this video demonstrates the concept well.
here

[DesignFlaw06]

In the article it claims that if you are riding at speeds and want to turn left and attempt to push your handle bars to the left you'll be turning right and vice versa , i mean WTF is that all about ?

This is one of those lessons that the MSF teaches. It was the first I had heard about it when I took the course.

[gammer]

The main thing is that you have to be going fast enough for this to work.
I've talked to allot of newbies who think you push the bars the opposite way on all turns...no matter what speed.

[Deadly]

In the article it claims that if you are riding at speeds and want to turn left and attempt to push your handle bars to the left you'll be turning right and vice versa , i mean WTF is that all about ?

http://auto.howstuffworks.com/motorcycle4.htm 

I thought the same thing back when I started riding. The booklet for the Missouri motorcycle test said this same thing and I thought it had to be a misprint. I didnt understand the concept of counter steering until about a year later.
I was out riding one day and for some reason that I dont recall right now I pushed the throttle side of the handle bars forward and the bike fell sharply to the right. Thats when it hit me that the MO motorcycle book was correct and it was not a misprint.

[MrF]

100% true, although it can be hard to believe until you've tried it once.  It has to do with changing the angular momentum of the wheel. 

Angular momentum is what keeps the bike wanting to stay upright when the wheels are turning.  To turn, you have to lean, and to lean you have to change that momentum.  That article uses the term precession to describe this, but that's not technically correct.  The wheel is just responding to the forces you're applying.  You can play around with this with a bicycle wheel with pegs or some other way to hold the axle on both sides of the wheel.  Get 'er spinning, (off the bike) then try to lean the wheel and watch what it does (watch your face and arms too, go easy at first, it seems almost 'unpredictable' but it's not).

Nerd alert!
Apply the right hand rule to the angular momentum vector with the direction that you're pushing on the bars and it starts to make perfect sense.
/nerd

[Bumblebee]

IMHO, the gyroscopic force turning explanation is essentially wrong. Gyroscopic forces, while present, do not apply as much as everyone implies they do. (Yes, it does affect the overall system a bit in terms of total forces involved however it does not make a motorcycle or bicycle turn and it doesn't resist the falling over as much as friction does) The same exact physics/dynamics apply to a snow bike (or whatever it's called) which is essentially a bicycle with skis instead of wheels and has no rotating parts of any kind. If gyroscopic forces were necessary, those things would fall over the first time you try to turn however in reality at 30mph they handle just like a motorcycle on pavement. If gyroscopic forces were required to turn, then why does a snow bike turn? No rotating parts = no gyroscopic forces and yet it still handles exactly like a wheeled motorcycle/bicycle; therefore gyroscopic dynamic effects are minimal at best and only affect the offsetting of the wheels when changing the axle angle of the wheel. This isn't about precession as much as it is about force vectors.



A simplified explanation: You can demonstrate this to yourself while doing slow school skills in the parking lot around 5-7mph by deliberately oversteering a bit. (Work your way into the deliberate oversteering and just be careful since you can dump yourself fairly easily doing this - If you fall down, don't come whining to me because you were careless)


First, lets get into the right mindset. Quit thinking in terms of turning. Think in terms of force vectors. When you enter a turn, you are NOT turning the motorcycle at all. What you are actually doing is manipulating force vectors that causes the motorcycle to change direction. Read the last two sentences again then think about it for a minute. (Hang man, you fly. The same principles apply when turning an airplane in flight. A plane turns for essentially the same reason a motorcycle turns, only the medium it's pushing/pulling against is different)

Going straight ahead, the center of gravity along the longitudinal (roll) axis of the motorcycle is over the tire contact point on the ground. Everything is in balance and it goes straight ahead and doesn't fall over. No problem.

Push left (or pull right) and the wheel turns slightly right. The wheels now track to the right out from under the center of gravity. CG is now to the left of the wheel so naturally the motorcycle starts to dump over to the left - just like it does when you stop and don't put your feet down. The CG horizontal force vector line starts extending out to the left and down you go. That's what's also happening at 0.1mph or 55mph. You're toppling over and will go down in a washout if you keep the handlebars turned that direction.

At this point, before you fall down and go boom, straighten the handlebars.

The side of the tires are now in contact with the pavement. If you look carefully and think about it for a minute, you can see how the motorcycle is not tracking straight ahead. It's actually rolling in a left turn circle. (Put the bike on the side stand with the handlebars straight and you can see this or better yet get a bicycle and roll it around while leaning it way way over) If you get too slow, you'll notice that the bike behaves as if it's trying to roll up a hill and it'll try to back up on you just before it falls over. This is where you get the pushed down in the seat forces during a steep turn.

If you're paying close attention to what's happening with the bicycle leaned way over, you'll notice that while the motorcycle/bicycle is turning, the front wheel in the turn is not exactly straight ahead as it is while going straight. It's very slightly turned to the left by a very few degrees or less. (This is the same concept as applying a little bottom rudder in a turn to keep the ball centered in an airplane) The bars are nearly straight however the bike is now tracking to the left in a circle since it's actually changing direction at this point. The front wheel is very slightly out of alignment with the rear wheel in the direction of the turn. What's essentially happening here is that the vertical force vector line for the offset CG is countered by the horizontal force vector of the left turn. This puts the total force vectors (CG moment and left turn force vector moment) straight down the vertical axis of the motorcycle which is tilted over. If you add up the force vectors, the CG is in line with the wheel/ground contact point nearly along the vertical centerline line of the motorcycle. It's now stable and doesn't fall over because the motorcycle keeps trying to roll back underneath itself which causes it to change direction.

The same forces apply to get yourself out of a turn. You turn the handlebars further to the left to force the wheels up under the CG vertical force line. If you look at the total force force vector lines as the wheels are headed back toward the CG vertical line, they are trying to make the bike topple over on the right side even though it's still tilted to the left.

You are now piloting the front wheel dynamically to keep the forces in balance. Too fast for the angle and the horizontal force line extends to the right and it straightens out. Too slow and the horizontal line extends left and the turn tightens. You have to change the force line with the handlebars to keep everything in balance. All you're really doing is moving the wheel/ground contact point off to the opposite side that you're trying to go so the bike will fall over in the direction you want to go then running the wheel back far enough to balance the forces so you don't fall over and up the hill (round the corner) you go.

The same dynamic forces that let you turn is also what causes a high side face plant. Just extend the force lines way out of alignment and jam them back the other direction really quick to let them catch on the other side for a return force line and it'll pitch you off the front then hit you in back of the head for good measure.


Don't think too hard about it while riding. Just let it happen as if it were going to happen anyway. Understanding what is going on helps you maneuver the vehicle more instinctively with experience which makes you a better rider.

[happycommuter]

i suspect this is the same principle for a bike , you are just shifting you CG to the left or right without actually moving the Handle Bars to the left or right...

Keith Code's No B.S. Machine was built to disprove this notion.

[Bumblebee]

I've only flown Powered aircraft once and i do know that it is a complete opposite of free flight

I have too much aviation, physics and real world applications background...

The hang glider and powered plane work on the same principles. The controls are just different. Aerodynamically they're essentially the same though one's a lot more draggy with less control.

If you think in terms of how an airplane operates, you'll see that a motorcycle is very similar even though it's operating in a different environment.

(BTW: There's a book called "Stick and Rudder" by Wolfgang Langewiesche. Get it and read it, it'll make you a lot better real world pilot)

you simply shift your CG to the left and right to turn

Again, you're only changing and controlling the force vectors, not turning the vehicle. Moving the CG is creating a force vector. (Gotta quit thinking like a cager)

you are just shifting you CG to the left or right without actually moving the Handle Bars to the left or right...

Nope. Won't work enough to do any good. Check out Happycommuters link to the No BS Machine.
You're using the handlebars to move the wheels out from under the CG then using lift (road contact point) to yaw into the turn. The g force increase is there to counter the total gravity vector since the motorcycle/airplane doesn't loose weight when it rolls over to the side.

[coffee_brake]

An excellent explanation (to complement Bumblebee's well-done post) of counter-steering is covered in David Hough's "Proficient Motorcycling." This book is for both newbies and experienced riders, I read it once a year and learn something new every time. I'm sure that applying knowledge gained from that book has saved my paint job, my leathers, and probably my life more than once.

[MrF]

We might be misunderstanding eachother a bit, Bumblebee.  Does countersteering work on a snow bike? 

I wasn't implying that gyroscopic forces are needed to turn a bike, just that you have to change the rotational momentum of the spinning wheels in order to get the bike to lean.

[Bumblebee]

We might be misunderstanding eachother a bit, Bumblebee.  Does countersteering work on a snow bike? 

I wasn't implying that gyroscopic forces are needed to turn a bike, just that you have to change the rotational momentum of the spinning wheels in order to get the bike to lean.

We're probably thinking a lot closer to the same way than it appears.

You have to overcome angular momentum to change the disk angle of the gyroscope. It's the displacement off center the wheel contact point that causes the bike to lean. The gyroscope just contributes to the motion. I believe we're in agreement.

And Yes, countersteering works on a snow bike just like a wheeled motorcycle. Slow, not so obvious, fast, definitely. Push right to go right, push left to go left. The article is implying that the gyroscope/wheel is the reason countersteering works however that's not true if you can do the same thing with a non rotating ski. Correct dynamic subset, wrong overall physics. IMO, a wider wheel or sliding surface will hide the countersteering motion more because you're just going too slow to observe it like you can at 15mph.

[MrF]

Gotcha.  I think we were saying similar things in different ways.

Never thought about how countersteering might work on something like a snow bike before. . .thanks for the insight!