I just bought an old, rusty mountain bike at a garage sale that I want to fix up to take to and from the Metro. It's a Diamondback Sorrento from sometime in the '90's. The bike rides, but the rear gears aren't shifting. The gears are Shimano Acera X. I want to replace the rear derailleur with a low end replacement. What do I need to know about compatibility? Will any Shimano rear derailleur work? Other brands? Thanks in advance.
Will any Shimano rear derailleur work? Other brands? Thanks in advance.
Any current and 95% of Shimano's older rear derailleurs will work. The exceptions are pre-1985-ish non-index and pre-1997 Dura-Ace derailleurs. You'll have to look very hard to find any of those, so we can round off to 100%.
Also, Taiwan-made Shimano clones (usually Sunrace brand) should work.
Avoid SRAM derailleurs with a number-dot-zero on them (3.0, 7.0, 9.0, etc.). These are not compatible with Shimano indexing.