REAR SHOCK ABSORBERS BITUBO HD051WMB03 HARLEY DAVIDSON FLHX (I) STREET GLIDE 2017 > 2020. The linear or progressive springs are chosen according to the vehicle. The big adjustments range grants an excellent use both with the only rider and full loaded. This is the reason why we decided to fit to these big scooters the same kind of suspensions designed for the motorcycles. Do not understimate safety and comfort granted by a quality suspension.