What's the practical difference between short cage RD and long cage RD?
 

What's the practical and functional difference between short cage RD and long cage RD? Why would I choose one over the other?

Thanks!

Adam

The difference is in the amount of chain it can "wrap up." The sum of the differences between the large and small cogs and chainrings on your bike determines how much chain you need to "wrap up," and this number is spec'd on each rear derailer. Simply put, if you have a triple chainring and mountain cassette, you definitely should use a long cage. If you have a double chainring and a corncob cassette, you only need a short cage.

Thanks!

A.