Fun with countersteering

[socalrob]

I've always countersteered at speed, even before I had heard about it. I was on a near empty freeway gentle curve this afternoon, & at about 75mph I decided to see what would happen if I tried to actually turn the handlebars into the direction I wanted to go, while leaning in the normal way. Not surprising, the bike straightened up & went the wrong way.

Now in a parking garage (slightly slippery floor) at sub 10mph, if I want to turn right I turn the front wheel right (no counter steer, no lean).

So my question is this. Shouldn't there be a magic speed at which it does't matter what you do with the bars? Twirl em around, shouldn't matter as your too fast for parking lot manuevers and too slow for counter steering. And what is that magic speed, as I guess I would avoid it as the bike would be stuck in a universe where straight ahead would be the only path.

[Leno]

It's not so much that what you do has no effect. It's more that it gets a bit vauge and wolly. I think the magic number is about 20 to 30 but a lot depends on what you ride. Slow corners can get intresting if you are around this speed. If you keep going round and round going slower and slower you will tip into a black hole.

[darthrider]

That "certain speed" depends on a myriad of variables and combinations of those variables.
But you raise a very interesting question...for any given set of variables, is there really a "speed of indifference" where nothing works? Everything works? If so, why? If not, why not?
Dallara is on a road trip but when he gets back I bet he'll have a few hundred carefully worded paragraphs about it!

[BobFV1]

Now in a parking garage (slightly slippery floor) at sub 10mph, if I want to turn right I turn the front wheel right (no counter steer, no lean).

Rob - I suggest not trying to countersteer in a parking garage

[machew01]

Be sure to keep your head up and look where you're not going.

mac

[tor1150r]

I just started ready a book by Reg Pridmore. He has some interesting theories on countersteering vs. body steering and it all has to do with smoothness and control. He was a racer, true, but has written a book for all types of riding, including street.

I'll post when I'm finished the book, as I have already seen a few thing in his book that are contrary to what I was taught in various riding courses.


My bike is stored...so I'll have to try some of his stuff in the spring

[popgazer]

at sub 10mph, if I want to turn right I turn the front wheel right (no counter steer, no lean).

Interesting observation!
Actually, there's an angle change (or lean if you start from vertical position) at any speed, it is just too small though at low speeds to be noticeable. The physics works same at any speed. The difference is that the lean angle is so small it is overcome by the other forces mainly tire friction.
When the gyroscopes (wheels) are turning, the same push force on the handle bar yields a bigger lean angle, hence the noticeable CS.
If you'd give anything to experiment yourself (I won't!), try a swift (hard) push on the handle bar at low speeds, and you will see that the bike will lean/CS. However, in order to see the effect at low speeds you should do it from a vertical position, since in a leaned position turning the handlebar into the turn increases the tire bite.
If you are into motocross-ing, in mid-air apply the brakes to simulate a low speed then turn the handlebar, you will always get a CS.

[Simon D]

Dallara is on a road trip but when he gets back I bet he'll have a few hundred carefully worded paragraphs about it!

Priceless, simply priceless

And the really sad part is that I look forward yo reading them!

[darthrider]

And the really sad part is that I look forward yo reading them!

Me too...the guy knows his stuff!
And he learned it the hard way...doing it, not just thinking & talking about it.
All too rare.

[Lance1150]

I think it's clear that it's some sort of illusion. It has to be a consistent effect or their would be some strange black hole speed where magic occured.

I agree, wait for the scientist to explain this.

[solitario11]

I read his book and it change my riding! you use counter steering to get the bike to lean to where you are going, Reg Pridmore is like you lean your weight to where you want to go to get the bike to lean and turn that way, man it really works, I am ridng so much faster (at the track also) and it feel so much natural. at high speed in sharp turn I line my head with my left hand grip ( on a left turn) and I naturaly hang off the correct amount if need it, there is more acause, like pressure with your right knee and pressure with your left foot on the peg, ( again on a left turn). it does take a little practice after 20 years. An added benefit is that since you hold the bars so lightly your hands and arms get less tired.

[dallara]

Oh, no... Not again!!!

Darth, Simon... Don't know whether I should be flattered, or offended...

Anyway, no need for this to take up lots of paragraphs - just go back and read the previous thread on countersteering, and particularly at some of the links I posted from sources far, far more knowledgeable than myself:

http://r1150r.org/board/viewtopic.php?t=3883

Socalrob - the simple answer to your question is the one most often completely ignored whenever the subject of steering a single-track vehicle comes up - gyroscopic precession.

Discussions on motorcycle steering seem to always mention rake, trail, lean angle, body positioning, and countersteering... but you almost never hear even a whisper of gyroscopic precession. Why?

Hell, I don't know. It actually should be one of the most discussed points, as gyroscopic precession is very powerful part of the equation. Maybe some see it as mystical, or perhaps too esoteric... But it is the single most important factor when it comes to why a single-track vehicles steering characteristics *APPEAR* (and appearances can be deceiving... ) to change with speed...

Now it would help if folks would read these links carefully:

http://www.tonyfoale.com/Articles/Balance/BALANCE.htm

http://pdmec4.mecc.unipd.it/~cos/DINAMO ... fects.html

http://pdmec4.mecc.unipd.it/~cos/DINAMO ... torque.htm

Getting fully comfortable with the concepts in these articles should make the effects of gyroscopic precession clear, and make it easy to understand why it is the answer to your question... And it should also make it obvious why there is no certain, "magic" speed where steering characteristics *APPEAR* to change... Why?

Because they don't change. You actually still countersteer to initiate the turn regardless of how slow you are going (other than from a complete standstill...). What *DOES* change is the rotational inertia of the wheels, and hence their resistance to motion in planes other than the plane of the wheel - i.e. at very slow speeds there is very little rotational inertia in your two biggest gyroscopes (your wheels) and so it takes a very little, almost imperceptible, amount of countersteer to initiate the turn, which you quicly follow with "prosteer" (turning the wheel into the direction of the turn) to keep the motorcycle upright and not falling over.

As you add forward velocity (and hence, rotational inertia) each wheel becomes more resistant to changes of direction due to their gyroscopic precession.

This is easily demonstrated with the old bicycle wheel experiment. Just a bicycle wheel and something along enough to put through as an axle that you can grip on both sides of the wheel with your hands... First, spin the wheel as fast as you can get it going, hold the "axle" and extend your arms... Now, try and "turn" the wheel and see, and more importantly, *feel* what happens! If you really do try this I promise you will be *AMAZED*!

Now, try spinning the wheel very, very slowly... And notice how little effort it takes to initiate a change in direction.

If this doesn't answer your question, then nothing will... But get back to me if you want to get into it any deeper, as there is some other factors that can be fun, too... Like tire self-aligning torque (which is why we use air-filled tires instead of solid rubber ones) and mass about the steering axis...

Cheers!

Dallara