Shock Absorber Type 540 RoadHarley Davidson Pan America RA1 Suspension Optimization We replace the stock linear fork springs with progressive units for improved initial compliance and greater reserve in the second rate. Rear damping and spring rate are tuned for a more stable, composed ride. By slightly reducing excessive negative travel via a shorter strut, we maintain seat height while improving handling and comfort. Ecoline 540 Mono Road 46 mm Stepless spring preload