1. Park the motorcycle on a level surface.
2. Turn off the engine and allow it to cool down.
3. Locate the rear shock absorber. It is located under the seat, on the right side of the motorcycle.
4. Use a wrench to loosen the locknut on the shock absorber.
5. Turn the adjuster knob to adjust the preload of the shock absorber. The preload is the amount of force that is applied to the shock absorber when it is not compressed.
6. Tighten the locknut to secure the adjuster knob in place.
7. Repeat steps 4-6 for the other rear shock absorber.
Here are some additional tips for adjusting the rear shock absorber on a R1200C BMW:
* The preload should be set so that the motorcycle has a slight sag when the rider is sitting on it.
* The rebound damping should be set so that the motorcycle does not bounce excessively after hitting a bump.
* The compression damping should be set so that the motorcycle does not bottom out when hitting a large bump.
By following these steps, you can adjust the rear shock absorber on your R1200C BMW to improve the ride quality and handling of the motorcycle.
