Prior to the 1950s, the rear suspension of a Harley-Davidson consisted of a seat with springs on it (via HowStuffWorks).The 1958 Harley-Davidson Duo-Glide was the was the first Harley to have an ...

With the rear suspension still hanging free, check the new ride height. Here, a 3mm shim increases ride height by 12mm. Measure the change on your bike and make a note of it (8).