physics poll: counter-steering

i like this one.

Isn't there a tractor involved in this scenario somewhere though? 'Cz give me a tractor and a freshly planted corn field, and I could answer this question. LOL

 

I get it...

Both. It is both inertia of the bike and gyroscopic procession. Gyroscopic progression coming more into play as the speed of the bike increases.

Come to think of it, the whole gyroscopic stability and progression thing might explain why in some more in depth tests of carbon fiber wheels, they have described some increased instability with the lighter wheel at high speeds at certain point on track...

 

whoa... did you just spend $2.45 for $1 worth of traction? lol

 

You really need to read chapter 4 in Foale's book.

I'll wait for the first vote. In any case "This poll will close on Feb 23, 2030 at 10:11 AM"

 

Question? I'm riding with no hands and I lean into a turn at 50mph, what is my front wheel doing? Pointed to the inside of the turn right? I've tried to watch it but I can't tell nor do I have the instruments to detect it. Thanks

 

OK, read it...

what I found most interesting is the interconnection of the roll axis angular velocity and steering axis torque. I never took into consideration what is happening in your hands on the bars and around the steering axis. Fascinating, really.
I see the mention of lighter wheels in his discussion and his mathematical/computer simulation reasoning behind the lower effort at the bars required basically due to the lower gyroscopic torque.

As far as the answer to your question, it seems that based on his computer generated models, gyroscopic progression plays little in establishing roll angle velocity due to the minimal steering angles achieved during normal cornering (1-2 degrees). Interestingly, gyroscopic progression of the rolling motorbike DOES effect the torque around the steering axis and thus the needed rider balancing input at the bars... Cool.

I've been meaning to buy his suspension simulation software just for shits and giggles. I should get around to doing it...

 

Foale mentions this directly in the chapter referenced above. He runs a simulation where center of mass is moved 50mm in 0.15sec. He says that the bike behaves the same way hands off as hands on, but instead of rider induced torque around the steering axis causing the bike to lean, a body lean into the corner causes an initial bike lean in the opposite direction. this will steer the wheels OUT and basically you have the same thing happening in the countersteering example now. He states this happens "far too sluggish to be of any practical use in the absence of normal handlebar steering."

 

Some things are easier to accept than explain. Why ask why? Just be glad it works.

 

Take this video and apply it in reverse

 

The end of chapter 4 is an absolute avalanche of information...

 

The only important part is where he shows that force applied to a spinning gyro results in opposite torque 90 degrees along the axis of rotation.

I don't really care about the science, I'm just happy it works.

 

It's simple physics.

 

The wheel likely turn outwards (as if countersteering) intially, but yes...once the bike starts turning, the wheel is pointed in.

Danny Walker does a demonstration of this at his American Supercamp (awesome school, if you haven’t done it...me and Eddie had a ton of fun there).

You can countersteer, and the bike will lean...but the bike doesn’t actually turn (change directions), until the wheel points into the corner. He also has videos that illustrate this. Dude
Countersteers his ass off, the bike leans, but continues to go straight until the wheel points into the corner.

Look at every single picture of someone in the middle of a corner, club race to MotoGP, and you will see the wheel pointing into the corner.

The only exception is when someone is countersteering as the back wheel is spinning (aka “steering with the rear”).

 

Please change this guy's name to "Bingo Einstein".

 

Here's another interesting video about rotating objects.

 

And a change of skivies.

 

Quoting Foale:

 

And interestingly, this counter-counter steering effect, turning the wheel back into the corner to change in direction (induce yaw rather than roll), basically occurs due to the gyroscopic progression of the bike around the roll axis and is very significant. In other words, you don't actually reverse force on the bars to turn the bike inward, rather you just ease up on the countersteering pressure around the steering axis and let the bike's own self stabilizing mechanism (gyroscopic precession) turn the wheel.

 

Are you sure inertia is the term you want to use? Just like centrifugal force, inertia is more an imaginery force that one appears to experience in a moving frame of reference.
Really, it's the tire force from the countersteering effort that applies a torque that initiates the roll.



And for a correction of my own, I have been calling it gyroscopic progression, when it should be precession.

 

What would happen to a motorcycle with 0° angle of trail?