G'day guys strange question to ask, I just fitted my 2001 Dyna with Progressive fork springs as they are shorter in length than the stock one's Progressive supply two PVC spacers to be used, now I know PVC is a strong martial but how do you think it will hold up with years of abuse on these goat tracks we call roads in Australia my fear is that they may crack and collapse because I am not sure how much pressure is put on these spacers in the forks, maybe someone with knowledge on how front  forks work could help out here and put my mind at ease cheers.

No worries mate , been used for years in forks as spacers .

The fork spacers are usually polypropylene if it is black it is poly! white PVC. I received black 5mm thick poly spacers with my ikons. Poly is not as brittle and wont really crack like pcv can, but only usually after it is exposed to sunlight! I,m a plumber! Cheers Grant.

I use solid brass spacers....lasted 20 years so far.

 i always use steel tube about 1,5 m.m. wall thickness , machined up equal within 0.002" in lenght  , either way you must have steel washers top & bottom ,