Long cage vs. Short Cage ???

For a duallie ( RM7 ) which is it to better have a SC or a LC deraileur. What is the differenece other than the cage length, what is the purpose. I confuselled.

SC, get a 105 rear der. or an Ultegra der. the road der. are the best.

super short cage and a strong tight spring gives you mad good shifting, and there nice and light too.

in my understanding a long cage will serve better in the rm7 application since it is able to take up more cahin slack. Im not sure how much chain growth rm7s have so I cant tell you for sure which one is better. However you are also going to be limited as to the cassette choices with a SC der.

short chage, less chance og it getting caught up in stuff.

When using a short cage u should also get a road cog.
a short cage cant shift into the biggest cog on a mtb casset without it being damaged

A short cage derailuer will allow for full motion through the cassette, however the amount of slack that the derailuer will allow is significantly less.

I have a short cage on my Stumpjumper HT, and I can't run in the granny gear and 7+ in the back without the chain bouncing on my chainstay when off-power.

To figure out which size you need, you need to know the chain wrap capacity. I forget exactly how to do this, but I'm going to work in a few seconds, so i'll check the SOP on it.

A Road derailuer won't shift all the way through an 11-34 cassette, it will be stressed to its max extension before getting all the way up. At least in my experience anyway.

Yeah. I think the raod derailleurs are rated to 27 tooth max although I've used them on a 28 with no problems. Never tried a 32 or 34 but I'd guess it might not be able to do it. You use a long cage to take up the extra chain you have with a wide ratio set up. If you're running a double chain ring or single up front, go for a medium cage XT or XTR. If you regularly bash off rear derailleurs consider "disposable" LX quality or lower.

Im running a midcage XTR on a 11-34 cassette, Big Hit DH, Chainguide with noooo complaints. I love it and I always have perfect shifting. Before I went XTR I went weeks with no chain because it wasnt worth it to me to buy a deore since they only lasted a couple weeks.

I went through over 10 deores last summer, I went to an XTR in october and I havent had a problem yet…and that's after 3 derailleur hangers…

No regrets!

The length of the derailleur cage affects how much

get short cage cuz my friend steve rides an rm7 and he went through like 5-6 derailers until he went to short cage which he's had no problem with