Yes, 180 then straight to 400. You could sand the whole frame in 180 if you want to prime the whole thing, followed by sanding with the 400 to prepare it for paint. I didn't need to sand the whole frame on mine for primer, just some chips here and there, rough spots on the swing arm and rear section of the frame. You can spot sand anywhere that requires it to go to bare metal with the 180, as long as you prime it. 180 scratches will show through if you paint over it. 400 needs to be the final grit.