I've tried to search this but all that comes up are the 1" to 1 1/8" quill replacement adapter. Is it possible to switch to 1" threadless by just replacing the adjustable race with a threadless version while keeping the rest of the threaded headset? My bike has a shimano 600 headset that I am happy with and would like to avoid pressing new cups in if possible. Am I missing something or is the only difference between yhreaded and threadless headsets the adjustable race?