Join Date: Jul 2007
Location: Anaheim, CA, USA
Because you stated "aggressive speed", you should apply both brakes together at the same time. Even though the brakes are linked, having good habits may help if you are ever on a different bike or there is some type of brake system failure.
Practice helps a lot.
Note that there are two different brake systems for current generation K1200GTs. The 2006 model uses servos, the 2007 and above do not. The front/back linkages are also different between the two types of braking systems.
The physics of braking a motorcycle are the same for K1200GTs as they are for other bikes. The goal is extract the maximum friction from both tires and the road. As the forces shift forward and additional weight bears down on the front tire, you can squeeze the front brake harder without skidding. Likewise, there is a reduction in weight on the back tire, so you have to ease up or the back tire will skid. Of course, the ABS prevents skidding by releasing the appropriate brake just before a skid occurs. Not all bikes have ABS, and ABS can fail on bikes that do have it, so good braking technique is useful.
The 2007 K1200GT has the best brakes of any bike I have seen. About six months ago I had a chance to compare the K1200GT against a wide variety of other bikes including other BMWs, Harleys, Ducatis, and more. There was an emergency braking exercise on a flat dry asphalt surface. Each rider got several turns to make a straight run, then emergency brake at a marker. There were lines to show stopping distance. For two of my turns, I decided to jam on both brakes hard, to see what the ABS on the K1200GT would do. It was impressive, and bested all of the other bikes in the course. Frankly, even with a lot of practice, it is hard to best the K1200GT ABS system.
Bottom line: Use both brakes when riding at "aggressive speed".
Note: There are cases where using one brake or the other helps. I use only the rear brake in certain low speed situations, such as parking lots. I may use only the front brake at a red light, so I am ready to plant my right foot and operate the shifter with my left foot. It depends.