Long cage vs. Short Cage ???

[bullit_kid]

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.

[-rigid man-]

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.

[Alexey]

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.

[Midas]

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

[inshane]

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

[BAC5.2]

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.

[Oldfart]

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.

[WBC]

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!

[usa_hucker]

The length of the derailleur cage affects how much “chain slap” you will experience. A short cage will work on a mtb but it will limit the amount of gearing you will be able to effectively run. If you want more info on that then do a search for gear inches or chain wrap, there are plenty of websites that do a better job of describing it then I could. Essentially, the shorter cage has less of a moment arm (get out the physics books) so it takes more force to make the cage move back and forth. This distance is also shorter because of the shorter cage length. If your running a single chainring up front and you need a new derailleur then get a short cage, it bounces around less, has a greater clearence, and ummm, that’s it. I’m running one on a single pivot bullit so they will work with any FS.
Ciao.

[OCRONPORD]

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

[dhoryxboy]

i ran a short cage xt with a short chain on my rm7 and it was fine