The throttle is the motorcycle's most abused control, primarily because it's so damn exciting. It has the ability to stabilize the motorcycle, assist in direction changes and - even on relatively modest machines - produce huge acceleration and deceleration. All at the twist of a wrist...
Too bad then that statistics show throttle mismanagement is responsible for most single-motorcycle crashes. Any idiot can accelerate hard and, as I write this on Wednesday morning I can hear motorcycles howling in our Soi, probably another customer who beliefs that his bike is not performing well. All too often this is followed not long after with a hospital visit, and major repair work.
A moving motorcycle is most stable when it's upright and traveling at a constant speed on a smooth, level road. To achieve this constant speed, the throttle needs to be open and the engine pulling enough to equal the drag. Any change in direction or speed will destabilize the motorcycle to some extent and the more significant or abrupt the change, the greater the destabilizing effect. This is why being smooth on the throttle is critical to fast, safe riding. One reason for this is grip. Snapping the throttle open does not allow sufficient time for the weight to transfer from the front tyre to the rear - and not enough weight on the rear means you won't have enough grip. Snap the throttle open in a bend and it can easily result in an immediate rear wheel slide.
Being smooth also minimizes the effect harsh actions can have on you, the rider. It's easy to unsettle yourself without realizing you're doing it. Snapping the throttle shut to deal with corner after accelerating hard can prompt an instinctive grab at the brakes. The resulting locked front wheel or air under the rear wheel will take your concentration away from the corner itself.
Even the best riders can fall foul of this problem. In recent MotoGP race Valentino Rossi out-braked another rider purely because the other rider was fighting for control of his bike, which was waving its rear wheel in the air at the time. The critical difference between the two riders - and one that is just as important on the road - is in the transition between one input and the next. Looking at the slow motion, you could see Rossi taking longer to close the throttle and apply the brakes. This meant weight was being more effectively transferred from the rear of the bike to the front and the small but important extra time allowed the suspension to react. The combined effect of all this was that the tyres could grip to their maximum efficiency.
Getting a smooth throttle technique takes practice. Choose a deserted road, ride in first gear and alternately accelerate and decelerate, trying to smooth the transition between inputs as much as possible. Slowly build up your transition speed, noting how the grip of your right hand changes.
Beware: There is a natural tendency to grip too tightly as the transition becomes faster, which stops you staying loose. This makes the transition seem faster, which means you grip tighter... Once you ge it right, a joyous side-effect of this exercise is that if you carry a pillion, they will head-butt you much less often.