# Short/Medium Cage Derailleurs?



## Greg (May 14, 2009)

I've heard recommendations to go with a shorter cage derailleur when I need to replace it. I guess the reason is obvious - less chance of it getting ripped off over rocky techy sections. Question is why do manufacturers usually default to a long cage? Is there a benefit to it? Is it only needed if you run with the biggest ring?


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## Gremf (May 14, 2009)

I always understood it as a requirement for the number front rings and their sizes you are running.  On my IH I have a long but really only need a medium because I am running a bash guard where my large ring used to be.


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## bvibert (May 14, 2009)

AFAIK the longer cages are to give you enough chain to work on the big ring and bigger cassette cogs while still being able to take up the slack to work on the small ring and smaller cassette cogs.


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## Highway Star (May 14, 2009)

Is that anything like a short to medium sized halfpipe?


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## Marc (May 15, 2009)

bvibert said:


> AFAIK the longer cages are to give you enough chain to work on the big ring and bigger cassette cogs while still being able to take up the slack to work on the small ring and smaller cassette cogs.



Correct.  If you're using a chain (generally speaking) on wide range of cog/ring sizes, you need a long cage to have capacity to take up the slack of using a chain that's really way to long on your smallest cog combo.

Remember the 'cage' is really just a chain idler.  The more slack you have, the bigger the idler needs to be.  The wider your range of cog sizes, the bigger the chain has to be, the more slack will be present on the smallest combo.


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## eatskisleep (May 15, 2009)

I run a Shimano Deore SS Short Cage road derailleur on my mountain bike.  Better than any other derailleur I've used on the bike.


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## bvibert (May 18, 2009)

eatskisleep said:


> I run a Shimano Deore SS Short Cage road derailleur on my mountain bike.  Better than any other derailleur I've used on the bike.



Do you only run 1 or 2 rings up front, or are you just really careful about gear combinations?


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## eatskisleep (May 18, 2009)

I run two rings up front... I had no problems with two rings up front and 9 speed in the rear. Currently I run two rings up front and 5 cogs on the rear cassette, I dropped the gears I used least, it's a sweet setup and it gives me a really straight chain line too.


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