Originally Posted by HillRider
Originally Posted by CdCf
However, I'm running an XT long-cage rear derailer with an excess of 49-50 links.
I can't shift onto the smallest five rear sprockets when using the granny, but that's the only problem. And it's not even a problem, since those combinations are duplicated using better combinations.
As long as you understand the limitations, a derailleur with insufficient wrap capacity is perfectly fine and it's done all the time. I'm running Shimano 105 9-speed with a triple crank but have substituted a 26T granny for the 30T. My rear derailleur, theoretically, can't handle the range. It does fine but I have to avoid the 26 x 13 to 15 combinations. No loss.
While the lack of tension makes it easy to drop the chain, a poor tension yields a lousy response of the drivetrain that begins to waver. Usually the last 3-4T of the rear derailleur capacity makes riding lousy. However, everyone is free to make his choices.