The 'Original' Progressive Rate Fork Springs soak up the small road bumps| yet are firm enough to absorb the molar-rattling ones. Spring rates have been chosen to reduce front end dive during braking| yet still provide excellent ride comfort. Better yet| Progressive warranties their fork springs for life! Progressive Rate Fork Springs have several advantages over straight rate springs. A Progressive Rate Spring has the advantage of a rising rate resistance to compression. The benefit of this is that the spring can be soft enough at the start of the travel to offer a plush ride| yet be firm enough at the end of the travel to soak up the big bumps. Some applications are offered in Heavy-Duty and Standard versions.