The second advantage is related to inertia (that is, the tendency of an object to oppose a change in state) both of the vehicle and the rotating engine parts. During acceleration, the driving torque transmitted to the ground pushes the vehicle, which reacts by generating a tendency to do a wheelie. Due to inertia, the counter-rotating crankshaft generates a torque in the opposite direction, which thus tends to lower the front end thereby reducing the wheelie phenomenon, with also benefits acceleration.
Likewise, during braking or fast decelerations, the motorcycle experiences a reaction that tends towards rear lift-up, but the crankshaft also undergoes a deceleration (reduced rpms) and this results in an inertial torque in the opposite direction that counters the force seeking to lift the rear end. Consequently, both in acceleration and braking, the adoption of the counter-rotating shaft provides positive effects.
Clearly, this layout requires an additional toothed wheel, the so-called idle wheel (*), which is necessary to transfer the crankshaft motion to the gearbox and then to the wheels so as to provide the correct rotation for the direction of travel.
* The presence of the idle wheel determines the need for an additional transmission part in the system that connects the crankshaft to the wheel. This must be considered when determining the power at the crankshaft if this is derived from the value measured at the wheel. For type approval and when testing on a chassis dynamometer it is necessary to consider a performance or in any case an additional coefficient that, by law, is set to 0.98.