Originally Posted by
Lohengramm
Hello, I was wondering how do I replace a rear derailleur. Like what do I need to know. Will any rear derailleur work? Can I put a 3x10 rear derailleur on a bike that is 3x7 and I just won't use the full range? I am asking because I am looking for one on craigslist. And anything else I should know?
Also, since I already need to replace my derailleur is it worth it to spend a little more oney and just upgrade to 3x11 speed? What is involved in doing that? Is it just cassette, chain, and the shifter?
Rear derailleur "attributes":
Rear derailleur
What can be combined with what (compatibility):
4) Bicycle rear derailleur compatibility - Bike Gremlin
I'd not call 3x11 an "upgrade", but a "change". It has it's good and bad points.
For going to 3x11, you need: chain, cassette, derailleurs, shifters and, if it's a road bike cassette, you'll need an 11 speed freehub (usually requires a rear hub/wheel change). A MTB 11 speed cassette will fit an 8-9-10 speed freehub just fine.