Cornering...

So let's get this clear: what exactly are you saying is responsible for
turning the bike?

 

As part of my newly-assumed role as monitor of the scientific
literature pertaining to motorcycles~[1], try this:


@Article{cossalter-doria-lot99,
author = {Vittore Cossalter and Alberto Doria and Roberto
Lot},
title = {Steady turning of two-wheeled vehicles},
journal = {Vehicle System Dynamics},
year = 1999,
volume = 31,
number = 3,
pages = {157--181},
abstract = {When driving along a circular path, the driver of a
motorcycle controls the vehicle mainly by means of
steering torque. If low steering torque is
necessary, the driver feels that the vehicle is
manoeuvrable. In this paper, a mathematical model
concerning steering torque is developed; it takes
into account the actual kinematic behaviour of the
vehicle and the properties of motorcycle tyres. Tyre
forces act at the contact points of toroidal tyres,
which are calculated according to kinematic
analysis. Non-linear equations are solved using an
iterative approach. Several numerical results are
presented, and the influence of tyre properties and
some geometrical and inertial properties of the
vehicle on steering torque are discussed. }
}

I haven't the time to read it properly, but it has lots of sums and
includes wheel gyro effects and tyre effects among other things.

 

Think about it - the amount of force you're applying to the bars when
countersteering is tiny - certainly not enough to tip 250kg of rider and
bike on its ear in half a second. The gyroscopic effect may contribute, but
that contribution is negligible.

 

the cont known as Porl says...

The rider

 

Magic, innit.

Or conservation of momentum, if you want to be more geeky.

 

But didn't you argue against me when I said earlier the same as:

"forces are generated as a consequence of the bike's desire to travel on in
a straight line."

 

Actually, not really. Camber thrust doesn't have all that much effect on
steering. The amount of camber thrust generated by a leant-over bike is
pretty small - not enough to account for the turn radius. You continue to
turn mainly because the bars are turned slightly into the turn.

I read it on the internet, so it must be true.

 

Nuh-uh. See my other post - a bike with two-dimensional tyres would still
turn the same way (though not quite as quick). This rather excellent article
explains it: http://www.tonyfoale.com/Articles/Tyres/TYRES.htm

 

I can see why you have the perspective you do now. The article concentrates
on the physics of what is happening to the bike and tyres but doesn't
address the rider's input to any useful degree, hence countersteering is all
but overlooked, especially as the device with which to start the turn.

 

In my opinion, this is the definitive atricle on bike balancing and
steering:
http://www.tonyfoale.com/Articles/Balance/BALANCE.htm

And yes, it mentions gyroscopes and everything. Read the whole thing and
try to understand, before spouting off that one thing or the other causes
the bike to steer (as I love doing from time to time).

 

I have to say, although the Other Monkey comes across as a little bit
know-it-all, everything he's said on bike steering is completely correct.

You a physicist by trade, Simian?

 

It's certainly not helping your case about how useful degrees are.

 

Oops, sorry. Erm... you're talking shit. That better?

Actually, what you said in that sentance above was true.

 

Look at the other Tony Foyle article I posted - that deals with
countersteering.

 

Whoops. I thought it was the same one you posted before. Well that's good.
Everything is pretty much as I thought it was and I can forget about it
finally and find another way to bother Auvache into an early ^H^H
better-late-than-never grave.

 

Actually quite a lot of it was. I feel quite, quite vindicated.

 

No. Leave it to Mr Foale. Posting that url has justified your existence,
that and your girlfriend of course.

 

OK, try this one - imagine a 50kg bike, with a 500kg rider, going in a
straight line. Turn the bars to the left, hard. The bike tries to turn to
the left. The rider wants to carry on going straight ahead. Therefore the
bike turns left, but leans right, because it's being dragged that way by the
rider.

Any better?

 

She wouldn't be. Don't worry about that

 

Sally rocks. Although if I didn't exist, she may well be single, which kinda
negates the existance justification.