# What the difference between short cage and long cage derailleurs?



## ddrass (Jan 16, 2007)

Like the title says, I don't know the difference. What are they?


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## jd3 (Oct 8, 2004)

The long cage will handle a bigger gear range. A triple and /or a large cassett will need a long cage.


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## ericm979 (Jun 26, 2005)

The long cage can take up more chain slack ("wrap"). You need it if you have a triple on the front because there is a large difference between the large and small chainrings.


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## C-40 (Feb 4, 2004)

*cage length..*



ddrass said:


> Like the title says, I don't know the difference. What are they?


The cage is the portion that the upper and lower pulleys mount to. A long cage would be longer than a short cage! It provides more wrap capacity to handle a wider range of gearing. 

Campy offers short, medium and long cage models with 29,36 and 39 teeth of wrap capacity. The wrap is the difference between the chainrings, plus the difference between the cogs. My 53/39/28 with a 12-25 has a wrap of 38T (25 + 13).


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## TurboTurtle (Feb 4, 2004)

ddrass said:


> Like the title says, I don't know the difference. What are they?


For Shimano with a standard crankset, the short cage is for a double and the long for a triple. You have to check the capacity which is the tooth difference between the largest and smallest ring on front and largest and smallest cog on the rear. The wide gap on the compact doubles and a wide range casette may also require a long cage. Campy also has a third, even shorter one for some reason that is used for doubles with narrow range cog sets. - TF


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## ddrass (Jan 16, 2007)

So a double up front and a 12-25 cassette could use a short cage?


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## TurboTurtle (Feb 4, 2004)

ddrass said:


> So a double up front and a 12-25 cassette could use a short cage?


Tha capacity of an Ultegra short cage RD is 29T.

http://bike.shimano.com/catalog/cyc...<>ast_id=1408474395181674&bmUID=1181854502922

For a 53/39 crankset: 53-39= 14
12/25: 25-12= 13
Total= 27, so you're good to go.

TF


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## Clevor (Sep 8, 2005)

ddrass said:


> So a double up front and a 12-25 cassette could use a short cage?


You don't say whether you have Campy or Shimano. If Campy or Shimano, the short cage is fine I believe. Campy goes into detail on what cage you need (based on the rear cog) on their web site.

Campy no longer makes long cage derailleurs (Record triples anyway), as of 2006.


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## ddrass (Jan 16, 2007)

Sorry, its Campy.


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## cq20 (Mar 24, 2007)

Clevor said:


> Campy no longer makes long cage derailleurs (Record triples anyway), as of 2006.


Campagnolo market 3 long cage derailleurs; the 9 speed Champ, the 10 speed Race & the 10 speed Comp.


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## lawrence (May 17, 2005)

In addition, the difference between the long, medium, and short derailleurs is the length of the cage. The cage is those 2 idler wheels on the rear derailleur. In a short derailleur, the idler wheels are closer to together while a long derailleur they are further apart.

Short derailleurs shift quicker than a long derailleur so it is not preferable to have a long derailleur on a regular double. With a compact crank you may find a long derailleur or a medium derailleur. I don't know if you would find a short derailleur. The smaller chainring of a compact crank could be a 34 or a 37. The smaller it is, the longer the derailleur to take up the slack when you shift.

Generally the chain is slightly longer with a long derailleur.

If the derailleur doesn't take up the slack, or doesn't take up the slack fast enough, the chain will come off the inner/smaller chainring. This is especially true of triple chainrings.


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## cq20 (Mar 24, 2007)

I replaced my compact double with a Campag triple. All I needed was a new bottom bracket and (of course!) the new cranks. The front mech works perfectly (I had to move it up a bit to accommodate the 52 vs 50 tooth big chain ring), the chain length is unaltered and the short cage rear mech is fine *but/because *I don't use small-small or big-big cog combinations. 

The front changing on the new setup works perfectly (actually it is better than it was with the compact).


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## C-40 (Feb 4, 2004)

*not all correct..*



lawrence said:


> Short derailleurs shift quicker than a long derailleur so it is not preferable to have a long derailleur on a regular double. With a compact crank you may find a long derailleur or a medium derailleur. I don't know if you would find a short derailleur. The smaller chainring of a compact crank could be a 34 or a 37. The smaller it is, the longer the derailleur to take up the slack when you shift.
> 
> Generally the chain is slightly longer with a long derailleur.
> 
> If the derailleur doesn't take up the slack, or doesn't take up the slack fast enough, the chain will come off the inner/smaller chainring. This is especially true of triple chainrings.


A long cage RD does not shift perceptibly slower than a short or medium. The upper pulley and parallelogram that make the shift happen are no different, regardless of the cage length. The longer cage just adds arap cpapcity. he long cage does not cause or contribute to the chain falling off the little ring. That's a FD or chainline problem. 

I've started using long cage RD's on my triple equipped bikes, since it allows me to use either a 12-25 or 13-29 cassette with no change to the chain length and there is no adverse affect on shifting. I can buy NOS Campy long cage shifters cheap on E-bay. Right now, I've got one bike running a medium cage and the other has a long cage. Can't tell a bit of difference.


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## Clevor (Sep 8, 2005)

In regards to Shimano, so they actually make a long cage triple derailleur? At what point,.e.g., rear cog size, do you need to use it? How about the front? If you go triple do you need to use a specific derailleur?


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## TurboTurtle (Feb 4, 2004)

Clevor said:


> In regards to Shimano, so they actually make a long cage triple derailleur? At what point,.e.g., rear cog size, do you need to use it? How about the front? If you go triple do you need to use a specific derailleur?


The long cage RD is for a triple - all cassette sizes.

The FD cage shape is very different for a triple. Using the double cage will probably work, but not as well. Whether it is 'good enough' is up to you.

TF


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