I have a CDale Prophet set up as a 650b. I want to reduce the travel on the Manituo 3 Way Air so that I can use the FR setting on the bike with 67.5 degree HTA. Is this a fairly easy thing to do (shim), or is this a nightmare? I was thinking that all I needed to do was add some shim behind the bottom out bumper.

Any help or guidance would be appreciated.

Thanks!