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I couldnt find anything on the search and Ive alwasy been wondering what the difference is between a short or a long cage derailler. Like which one would be better for drop and what the difference in shifting is. Thanks alot
Jim
 

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For DH/FR I think is better Short , less chances of hiting a rock with the cage... I had long cage and now I'm runing 105 w/SS cage and I feel no diference in the shifting and still can run 11-34 w/o problem.
 

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The shorter the better... it will shift quicker and be less of a target. But what you need depends on your chain ring and cassette sizes. The cage basically wraps up extra chain..

I can't think of where to point you to for more detail, but maybe someone will chime in..?
 

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Short....UNLESS you have a bike that exhibits a lot of chain growth (e.g. a Bullit). Without the chain-wrap "cushion" a long cage affords, you can rip off the derailleur when the suspension is bottomed, if you're not careful. Sometimes a longer cage is required to wrap up the extra chain you need to run with a single pivot bike (my old Marin Team DH had massive chain growth), as well as to play nice with a guide. YMMV.
 

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I found the answer. The rear derailleur has a total capacity associated with its cage size. This is how much slack chain it can soak up. The smaller the cage, the quicker your shifting is and the less target the cage is going to be.

If you look up the specs for a derailleur you'll find its total capacity.

To calculate the total capacity you need you calculate (number of teeth on largest cog - number of teeth on smallest cog) + (number of teeth on largest chainring - number of teeth on smallest chainring) = total capacity.

*You can get away with a derailleur that provides less capacity than you need if you stay away from the smaller cogs when riding in the granny.
 

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If you want to run 3 chainrings, you probably should not run a short cage rear deruiller. (Btut this probably doesnt apply to you since you are probably a freerider.) Like they siad, short cage is better becuase it is less likely to catch on rock and other things.
 

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I just got an '05 Sram X.9 medium cage (the short cage) and it is less of a target then my POS shimano LX SGS (long cage) but not by a whole lot because of how the Sram derailleur works. There are a lot of things you need to factor in when deciding what rear derailleur to get. From what I have read and been told is that a short cage limits your options as far as what chain rings you can run. I run 32/22 chain rings with a 11-34 cassette.

As far as a short cage shifting faster/better than a long cage I can't really compare because I went from total crap (shimano) to super high performance (Sram). If you are in the market for a new rear derailleur get an '05 Sram X.9 medium cage and the X.9 triggers or if you can afford the new X.0 triggers because they look sick. Don't waste your money on the X.0 rear derailleur this year because other than the titanium bolts, nuts and spring the '05 X.9 derailleur is exactly the same. So other than the X.0 being lighter (only 25 grams) and obviously titanium being stronger you get that really cool "carbon fiber" look sprayed on the Girlon (Srams composite plastic which both the '05 X.9 and X.0 use) you pay almost $100 more.

Sorry for such a rant about Sram but they rock so get a medium/short cage unless your using 3 rings which most FR/DHer's don't.
 
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