Development of CBS: Front and rear wheel interlocked brake

Honda paid attention to the operation of brakes unique to motorcycles; front and rear wheel independent brakes applied through levers and pedals in accordance with ever changing driving conditions from moment to moment. However, proper braking of front and rear wheels is required to stop efficiently in a shorter distance according to various road surfaces. Honda aimed at enabling ideal and easy operation of front and rear wheel brakes, which could be applied at anytime and by anybody. That is the purpose of CBS (combined brake system); front and rear wheel interlocked brake system.

Difference in brake characteristics of motorcycles and automobiles
The first thing to be considered in thinking about CBS, a front and rear wheel interlocked brake system, is the difference with automobiles. As compared with automobiles, the center of gravity is higher and the wheelbase is shorter, this makes the numerical value obtained by dividing the height of gravity center by the wheelbase larger than for automobiles. This fact makes the shift in the gravity center for motorcycles at time of braking greater than that of automobiles.

Difference in brake characteristics of motorcycles and automobiles

That is why the braking characteristics of the front and rear wheels largely differ in motorcycles. The front wheel brake causes the shift of gravity center to the front wheel in accordance with the extent of deceleration taking place, so a high deceleration is obtained but the nosedive is large. The rear wheel brake, on the other hand, cannot yield deceleration larger than the front wheel, but the resulting nosedive is small.
The road surface conditions vary greatly by the pavement and weather conditions, whether fine or rainy, affects the riders ability to properly use the brakes of front and rear wheels to suit with driving conditions, making the most of features of respective brakes. CBS enables at anytime and for anybody to properly distribute braking force between the front and rear wheels in accordance with road surfaces.
Development requirements for CBS: front and rear wheel interlocked brake system
In conventional motorcycle brakes, the right lever controlled the front wheel brake while the pedal (or the left lever) controlled the rear wheel brake.
Honda aimed at simultaneous and effective application of the brake on the front and rear wheels by one operation. In the development of CBS, it has become necessary to assure that no sense of discomfort will be felt on braking characteristics and motorcycle body behavior by the riders accustomed to the conventional independent front and rear wheel brake application. Therefore, the following three points were aimed at in the development:

1.  The braking force on the front wheel is to be raised higher when power is applied on the right lever while the same on the rear wheel is to be made greater than the front wheel when power is put on the pedal (or the left lever).
2.  Nosedive tends to become large as the front wheel brake works when the pedal (or the left lever) is operated. Make the dive as small as possible.
3.  Lessen the mutual interference between the right lever and pedal (or the left lever) at time of joint operation.


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