I have installed a lot of the progressive monotubes in trike and 2 wheelers. 2 spacers will be good even for heavy riders and 1 spacer is a bit softer ride and will also lower your front end down about 1.5 inches. With the lowering of your front end you might get fender to lower triple tree hitting. I would go with the 2 spacers and you want regret doing the mono tubes. They work great . Just make sure you put the correct amount of fork oil back in . It is critcal on the ounce amounts. Just refer to your Harley manual for your year. Hope this helps Booggerbe (Ron)