That sensor let's the ECU know how far and how fast the fork is compressing and rebounding. Without some sort of sensor the computer has know way of knowing. There is a sensor that comes on the rear shock. So in stock form BMW uses damping a combination of compression and rebound that can be set instead of the individual parameters. On the front DDC forks.I don’t understand what role a linear sensor has in separating compression and rebound. I don’t have a clue how the system works, but I imagine there is an electro-mechanical device that changes the fluid flow. Why can’t that be set for compression and rebound by dialing in a number for each. In order to get dynamic damping you would need a sensor, but static ???