Derailer - Rear - SunRace RD-M10

SunRace RDM10

This is the cheapest good derailer we're aware of, the derailer you want on your jungle and dessert bike. It shifts to 28t. It doesn't index. It is designed to shift up to 7 speeds, but we get it to go eight on a 9-speed casette. It used to be made as a FALCON brand, but SunRace bought FALCON years ago, so now it's a SunRace. It weighs less than most SHimano derailers, even though there isn 't any aluminum in it. 

All of the derailer's functions are exposed, so you can see  how it works, and that's its purpose here. We don't expect you to take off a perfectly good Shimano. Get this and don 't even put it on a bike (unless you have a bike that needs it). Play with it in your hands and see how the limit screws work, how the springs in the body and the pulley cage work. You'll see plainly that all a rear derailer does is shove the chain inward and pull it outward to get the gears, and the limit screws prevent overshifting. It's a neat mechanism, worth every cent.

Frictions up to 8.
Wraps 35 teeth*.
Max rear cog, 28t
Wt: 255g

* What's "wrap"?
It’s the difference in big and small chainring teeth PLUS the diff btw big and small cassette teeth. For instance:

Big chainring 42. Small 28. That diff is 14.
Big cassette tooth 32, small 11, that’s 21 diff.

Add both diffs, 14 + 21 and that's a wrap of 35.