Hi Ken. I actually just had Les at LTR setup the suspension on my EC300 for a 280lb load(260lb rider + gear). I think you should be looking in the ballpark of a 5.8 or 5.9 rear spring. Les recommended the 5.8 and the Ohlins Spring Tech I spoke to recommended the 5.9. Sorry 42GEORGE for adding to the post high-jack.