Quoting from BMW Press Packet:
The new ABS and the new BMW Motorrad Automatic Stability Control (ASC) The range of active safety systems and the systematic further development of these systems make a substantial contribution to BMW Motorrad’s market success. With this in mind, BMW Motorrad considers itself obliged, concurrent with the ongoing model campaign and a range of vehicles with enhanced dynamism, to also offer the market an all new BMW Motorrad ABS System. But that is not all. For the very first time and as a worldwide innovation a traction control system is now also available for BMW Motorcycles – the BMW Motorrad ASC (Automatic Stability Control).
1. Integral ABS II
The new Integral ABS II from BMW Motorrad optimizes the braking system and aligns it even better to the rider’s requirements. It improves braking performance on uneven road surfaces, ensures more homogenous control and, via the brake lever, provides feedback if the adhesion limit is exceeded and the control range reached. Ease of maintenance is further enhanced by the extended diagnostic functions. Maintenance costs correspond to those of machines without ABS. The power requirement is significantly less than that of the previous system.
The expert eye will immediately notice that the new integral ABS is distinctly smaller than the previous version. This is a genuine added value for the customer since a reduction of the weight will positively affect the motorcycles agility and dynamism. In direct comparison with the previous Integral ABS the new system enhances the brake system and adapts even better to the riders requirements. The new electronics ensure a more sensitive response of the system to road surface deficiencies. The control processes are even more homogenous and provide a distinct feedback to the rider via the brake levers. The rear wheel lift off control is also improved.
To achieve optimal deceleration, (that is, the ideal distribution of the brake forces at the front and rear wheel), BMW Motorrad took the decision to further develop the ABS system in the partly integral version, pursuing a policy of systematically perfecting the ABS system, taking into account the sportier orientation of BMW Motorrad’s entire product range.
Deceleration on a conventional motorcycle means that there is a higher load at the front wheel, and as a result this wheel can transmit more brake force. In contrast, the load at the rear wheel is less, meaning that this wheel can transmit less brake force and is thus also more likely to lock the rear wheel. Operating only the rear wheel brake has a comparatively small braking action and can result in an early lockup. With the new Integral ABS II braking system, the optimal distribution of brake forces at the front and rear wheels is ensured.
Even the power consumption has been reduced in comparison with the predecessor, the omission of the brake booster furthermore eliminates the noises heard when holding the brakes on during stops. Another important side effect is the fact that the ignition will no longer have to be switched on when moving the bike to achieve enough brake force.
Principle features of the new Integral ABS in a nutshell:
- Significantly improved metering compared to I-ABSI
- Optimized pressure modulation for improved braking efficiency
- Weight reduction of 2.2 kg/4.85 lb (50%) compared to I-ABS I
- Maintenance costs as for machines without ABS (cost of ownership)
- Optimized rear-wheel lift off control
- Improved braking performance during moving the bike, even when the ignition is switched off
- More dynamic adjustment of the optimal brake force distribution to the load distribution
- Extended diagnosis function and system monitoring
- Reduced power requirement compared to I-ABSI
- Improved feedback with respect to ABS braking
- I-ABS II provides data for the ASC via the CAN bus
ASC is an assistance system that helps the rider and offers enhanced safety on surfaces with a reduced friction coefficient. Within physical boundaries, it limits the drive torque transmitted, thereby largely preventing the rear wheel from spinning. As a result, ASC is not designed for the racetrack, but for everyday use on public roads with differing road surfaces and a frequently changing adhesion coefficient of the given road surface.
BMW Motorrad is currently the only manufacturer to offer ASC for motorcycles as an addition to Integral ABS. This is yet another example of BMW’s lead in motorcycle safety and innovation. ASC is an available option for 2007 models.
The ASC supports the BMW rider on roads with varying and lower friction coefficients. It is particularly attractive on roads where the road surface and condition for tire adhesion usually vary – a fact that every motorcyclist is aware of. Depending on the road condition, the ASC will limit the drive torque transferred by the engine within physical limits, to where an uncontrolled spinning of the rear wheel will largely be prevented. Apart from the considerable safety gain, this also means a more efficient use of the power that arrives at the rear wheel – since the ASC will only make available as much power as the rear wheel will be capable of putting on the road.
The ASC control works as follows: the ASC uses the signals of the ABS wheel speed sensors and evaluates these signals. The current wheel slip is then determined on the basis of the speed difference between the front and rear wheel. In order to allow for an improvement of the directional stability, the wheel slip will then be limited to an acceptable level. This is achieved by the engine management that retards the ignition or suppresses individual injections if a higher level of control is required.
The ASC control mode will be indicated by a rapidly flashing ASC warning light. If the intervention of the electronic system is not wanted, the system may easily be deactivated by a simple push of the button – while riding.
The ASC system – similar to all electronic systems used by BMW Motorrad – features a self-diagnosis capability, which means that the rider will be informed immediately, should the ASC function not be available.
A special off-road setup has additionally been developed for off-road use, specifically for the R 1200 GS and R 1200 GS Adventure. This setup is adapted to the specific slip situation encountered on loose ground, such as sand or gravel. A push of the ASC button shifts the system from the on-road to the off-road mode. In off-road mode it is not suitable for on-road riding.
Benefits of the BMW Motorrad ASC
- Largely prevents uncontrolled spinning of the rear wheel
- Provides support for the rider by maintaining the directional stability
- Only puts as much power on the road as the rear wheel will be capable of transmitting
- Additional safety on roads with lower friction coefficients
- Specific off-road setup for the R 1200 GS and R 1200 GS Adventure
- The ASC may be activated / deactivated while riding
The ASC provides additional safety in critical riding situations as a result of unforeseeable road conditions.