Chassis geometry is not fixed

You have heard of cars that have toe control and other passive features which allow the rear wheels to turn slightly in sympathy with the front wheels for greater maneuverability. But, the fact is that a car's steering geometry is more or less fixed. However, a motorcycle is a different creature. Racing motorcyclists worry so much about setup, for the bike is not a fixed entity. When the front suspension dives, it changes the chassis stance. Ditto acceleration. What I'm about to try to explain is that, this is not a bad thing. This is a tool good motorcyclists use daily. And so should you.

The steering character of the motorcycle is largely represented by the rake/trail figures. Yes, wheelbase, chain angle etc play a part, for our purposes let us omit them from this discussion. The rake of the bike is simply put the angle between the vertical and the axis that runs through the steering head, measured in degrees. When the motorcycle is braking, it's chassis 'tips' forward, changing that angle. The exact opposite happens under acceleration. The second is trail. This is the length, in mm, between the vertical axis that passes through the front axle, and the axis that runs through the middle of the headstock (not the forks!). In general, the steeper (smaller) the castor angle, and the smaller the trail length, the quicker the motorcycle with turn, and the more unstable the motorcycle will be, respectively. Without going into the hows and whys, the trail is one of the components that makes a motorcycle want to center its steering. The more the trail, the stronger that force is. This manifests as an (un)willingness to turn, or a feeling of heaviness in the front. One of the reasons cruiser front-ends feel a fair bit heavier and ploddy than superbikes is the huge rake angle, and the solid amounts of trail that go with the cruiser chassis.

To return to our discussion. Let's look at a rider beginning his corner exit. As he opens the throttle, the weight transfers backwards, causing the rear suspension to squat, the forks to expand. This is accompanied by a slight rise in the castor angle and trail. Which causes the motorcycle to widen the line and the radius of the arc broadens. The more you open the throttle, the wider that line will become. Similarly, when you enter the corner off the throttle, you've just sharpened the rake angle a bit more than standard, and it becomes easier to steer or the motorcycle takes a narrower line. That is also the reason why motorcycles demand more effort when coming into corners with the throttle open. There are other ways to use this also. For instance, I prefer to roll into intersections off the throttle. It transfers the weight forward, so I can brake harder, quicker if I should need to. And the chassis is tipped forward to steering around an obstacle/cager is quicker and easier.

This chassis behaviour is why all race schools say the same thing. Brake before the corner, turn in with the throttle closed, maintenance throttle at the apex (rolled open just enough to hold the line/lean), and then smoothly roll back on to make a widening line exit.