SDBV(Showa Dual Bending Valve)

 HARLEY‐DAVIDSON offers full‐dress touring models whose total vehicle weight can vary significantly depending on the accessories mounted, loads, and single vs. double riders. Not only should the suspension demonstrate good riding feel but also its behavior must not be affected by the amount of load on the vehicle. The need to make improvements to the front fork has arisen especially for a situation where strong braking is possible with an ABS system, potentially causing a sudden nosedive. The structure of the conventional free‐valve makes it difficult to generate the compression‐side damping force at low piston speeds (suspension operational speeds) where nosedive is to be controlled. The “SDBV (Showa Dual Bending Valve)” solved this issue. Since “SDBV” can generate stable damping force characteristics, it has an advantage of being able to suppress the floating of the vehicle body caused by irregular undulations of roads. Because its basic structure being similar to the free‐valve type, the SDBV can keep the increase of cost/weight to a minimum and can be applied to different models because of its mass producibility.

This product uses a newly developed valve unit, to realize stable damping characteristics

 The free‐valve type, the basic structure of the normal type front fork, has been applied to many different models. However, the issue of the free‐valve structure is that it cannot sufficiently compensate for vehicle posture changes, because the damping force rises more steeply than the linear curve with respect to change in piston speed (square characteristics) due to the damping characteristics being generated by the orifice.
 The “SDBV” uses a valve unit of a new structure in place of the free‐valve structure. Check and disk valves are placed in rebound/compression sides independently to control damping forces. This valve unit generates damping force characteristics that change linearly between low and high piston speeds, improving the ride feel especially on severely uneven roads. The improved responsiveness allows the tires to grip the ground firmly and provides reliable braking and handling performance.

SDBV(Showa Dual Bending Valve)SDBV(Showa Dual Bending Valve)