<< Basics of Motorcycle Suspension
The spring is (for the most part) wound steel and is defined by its rate.
Rate is a measurement of the force required to compress the spring and is expressed in lbs per inch. For instance a spring with a 100 lbs/inch rate will require 100 lbs to compress it one inch. Each subsequent inch of compression would require an additional 100lbs of force. This is referred to as a straight or linear rate spring. The alternative, is a progressive rate spring which allows a single spring to essentially exhibit multiple rates. By utilizing varied spacing spring coils, the initial rate may be 60lbs/inch, requiring 60 lbs of force to compress it one inch. Then each subsequent inch of movement would require progressively more than 60lbs of force such as 75lbs more for the second inch, 100lbs more for the third inch etc, as shown in the example. Progressive-rate springs become stiffer quicker as they are compressed. The advantage is a spring that is supple enough to soak up small bumps, yet firm enough to handle a big hit.
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