Motorcycle Handling & Chassis Design

Tony Foale's brilliant engineering manual, Motorcycle Handling & Chassis Design, gives you an inside, technical look at how motorbikes operate.  It also gives you some idea of just how precarious the act of piloting a motorcycle is.  Much is said about how free people feel when riding and the physics behind flying on two wheels makes it that much more magical.

That first time you roll on the throttle and your feet leave the ground not to come back down again for miles, you get that sensation of flight.  Your senses are alive on a motorbike as the world makes itself felt in many different ways.

The naked exposure you feel when riding is obvious.  What is less obvious are the hidden forces at work that allow you to do crazy things like hang sideways while cornering.

Anyone who has seen a racing motorcycle suddenly hit the ground can speak to how suddenly these balancing forces can fall out of sync.  Foale's book is full of helpful diagrams that clarify some pretty arcane physics.

Cornering on a bike is one of the most complex and misunderstood aspects of riding.  Keith Code does a good job of explaining this in Twist of the Wrist.  Foale's approach is more interested in the mechanics of the machine and how it handles the forces working on it.

From a rider's perspective, corning is a balancing act, but from the suspension's perspective things get a lot heavier when you're bending into a corner.

Compared to a car, motorcycles have very different dynamics that often surprise riders when they are testing the extremes of two wheeled dynamics.  Reading Foale's book (though he pitches pretty hard) is worth it even if you're only getting a sense of just how differently the 'integrated system' that is a motorcycle works.

Foale also gets into the geometry of the motorcycle.  From wheelbase and centre of gravity to more complex issues like how suspension height changes those fundamental forces.  Of course, in a corner a the suspension is severely compressed, changing the bike's responses in dramatic ways.  You get a real sense of how connected and complicated the physics of riding is after reading this book.

The copy I read was the 2002 version, but he still managed to work some of the newer computer based analysis of motorcycle physics.  Static pressure and its role on aerodynamics is a relatively new aspect of motorcycle theory, but Foale covers it.

You can find the latest version of this technical manual online from Foale's website, but you can get a good idea of what it's all about from Google Books.  I'm curious enough about changes and updates that I think I'm going to spring for the new PDF ebook.

A State of Constant Surprise

On the bike I tend to pay very close attention to people piloting the boxes around me, mainly because they can quite easily hurt me.  That close attention has shown me that a surprising number of drivers (anecdotally more than half) are in a constant state of surprise.  They jump when they notice someone walking down the sidewalk, they start when a light changes in front of them; they are permanently startled by everything around them.

These jumpy people must be exhausted when they get out of the car.  I wonder if they are equally surprised by everything when they go for a walk.  Perhaps their subconscious is just continually reminding them that this driving thing is a bit more than they can manage.  Next time you're riding or driving try to consciously register how often you're surprised by events around you.

When I started driving I found that my mind wandered and I wasn't always paying attention to what I was doing.  After an accident (not entirely my fault, but I could have avoided it had I been paying better attention) I made a promise to myself to make driving the priority in my mind when I'm at the wheel.  I developed a relaxed, alert driving style that allowed me to take in what was around me while also being able to respond to it quickly and smoothly.  When I did something wrong or found myself in a bad situation I'd consciously review it and ask myself how it got like that and try think of alternatives for the next time.  It took me a long time, some advanced driving courses and some track time to get me where I wanted to be in terms of driving, but I don't look surprised or start at everything I see like a rabbit in a field.  I suspect most people are lost in thought when driving matters interrupt them, and if something bad happens embarrassment forces them to ignore it rather than critically review it.

Most drivers behind the wheel.  Being freaked out is not the
same thing as being alert or responsive.

If you don't make a conscious effort to develop a skill it atrophies.  Practice by itself isn't improvement, in many cases it's just reinforcing bad habits, which is what I see every day when I'm closely watching the habitual people around me with years behind the wheel driving in shock and awe.

When you consider that the last time most drivers made an effort to learn how to drive was when they needed to get a license, many of them are not only trapped in bad habits but have also forgotten what little they did pick up years ago.

People often say that riding on the street is a dangerous business, they aren't wrong.  Getting hit by a startled rabbit in a three ton metal box is gonna hurt, no matter how startled they are.  The trick is to see the rabbits and give them enough space to drive badly, it's all they know how to do.