Suspension Basics for BMW Motorcycles


Filed Under (BMW) by admin on 30-11-2010

tires: Tires are the first part of any suspension system. The design of the tire and even the pressure you run can have a profound affect on the way your motorcycle handles. Stiff, low profile tires will give a sharper feel to the bike, as will higher tire pressures. Those of us who ride our GS’s off the road will decrease the tire pressure to about 50% of the street spec when we are in the dirt. The tire then becomes a very active part of the suspension, but will wallow like an old pig if not re-inflated when pressed back into pavement duty. It still surprises me when we have a customer complain that his BMW needs new shocks when they come in with nearly flat tires. It is possible that the best dollars-per- unit improvement you can make to your BMW may be in keeping the tires inflated. Chassis: There is not much that we can do about the chassis design, unless we are Troy the Welder, but it is a fact that different frames and swing arms flex differently and therefore are part of the suspension. On the Airheads, we often braced various parts of the frame and swing arms, resulting in improved handling that even mere mortals could appreciate. On the latest BMW’s it would take the likes of a Valentino Rossi to even notice if the parts were stiffened. Stiffer is not always better. One of the Japanese racing bike manufactures controls the stiffness of the frame in various areas to allow some flex for better handling. So, Mr. Rossi might not even like it if Troy stiffened his new BMW. Springs: Springs control the ride height of the motorcycle and the ability to allow for different loads. On most BMW’s there is a way to adjust the spring preload to some extent so that the ride can be optimized for a light rider or two-up operation with luggage. Dampers: Dampers control the speed and frequency at which the suspension operates by changing the kinetic (moving) energy to thermal (heat) energy. Without the damper, the suspension would oscillate as each movement occurred, resulting in decreased vehicle control. Dampers on BMW’s fall into two main groups. On airheads, older K bikes, F and G models, and the R1200 HP-2, the front dampers are integrated into the forks. On the rear of the above mentioned -3 – models, and on both ends of all the rest of the bikes, there is a more common shock absorber, around which the spring is located. The HP-2 uses an air spring and air dampened rear shock. Seat: OK, folks, this is here for my old buddy Jeff. We know that a seat isn’t part of suspension, but a bad one sure can make you miserable. We have sent dozens of seats to our friend Mike Harris for inexpensive mods that might improve your riding enjoyment more than any suspension changes you could make! Let us know if we can help you with this most important item

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