Even though your handlebars move your front wheel left-right and can technically steer your bike left or right, once you are moving above around 20kph you won’t use this method to turn. The gyroscopic effect (precession) of your wheels plus your inertia means that the only way to make rapid turns is to use countersteering.
At low speeds you will still be using countersteering to an extent, but its process is masked by the multitude of minor balance corrections you make with the handlebars when riding slowly. It’s only when riding at higher speeds that you must deliberately use countersteering to effect a turn.
At first glance countersteering sounds unintuitive: steer right to turn left.
A bike can only turn when the combined centre of gravity of the rider and the bike are on the side that the bike is turning towards, and the bike leans into the turn. The angle of lean required will be related to the velocity of the bike – when the centripetal and gravitational torque in relation to the speed at which the wheel is rolling is balanced.
To make a left turn you have to get the bike to tip to the left, and the way to do that is to provide some positive input or ‘positive steering’: push the left bar forwards briefly (essentially forcing the bike to deviate slightly to the right), lean slightly to the left and the motorbike will lean nicely for you. As the desired angle of lean is reached, steering inputs through the handlebars keep it at the correct angle and help you get back upright again.
At low speeds it is usually necessary to steer in the opposite direction of the turn to maintain the turn. At higher speeds this gradually becomes the need to steer in the same direction as the turn.
Countersteering becomes a natural action you will perform to turn your motorbike. I vividly remember learning countersteering on a 50cc off-road scrambler when I was 11 years old – I had been put on the bike with very little instruction and, as I was a speed freak at that age, simply wound up the throttle to the max and set off. I had never ridden a motorbike before and when I found I couldn’t turn the way I turned my BMX, I discovered what countersteering was.
On a lighter bike, like a small off-road bike, it can be equally as effective to shift the rider’s weight, but this is not effective on larger bikes.
It’s important that you become really familiar with countersteering, especially in an emergency because this is the only way you can make rapid changes in direction. This question in the Road Code theory test deals with countersteering.
This video explains it.
Questions in the Road Code theory test relating to countersteering: