Originally Posted by
Clint in KY
UPDATE:
I chatted with a rep from Trek and she/he (name was Lo) walked me through quite a bit of parts interchangeability. Said, as others here have, that just the application is enough to find a suitable replacement. i.e. For the front derailleur just the function will work - Front Derailleur 3 Speed - is enough to find a replacement.
I'm learning......
I also watched a video on YT by Seth from Berm Peak which cleared up a lot mere.
That's not enough - you need clamp diameter or direct-mount type, top or bottom cable pull, also top bottom or side swing, no.of speeds because 12 speed chains are narrower than 7 speed chains, and newer derailleurs also have different pull ratios, so road and mtb parts aren't 'interchangeable. And some older SRAM stuff is Shimano compatible while some isn't. There's probably obvious stuff I've missed too.