Road Cycling - short cage vs. long cage rear derailleurs

How do you decide which you need? I assume it has to do with the cassette you intend to use.
What's the biggest jump that a short cage derailleur can handle? (12x25 or 12x27?)
We'd be talking about shimano ultegra here if it makes any difference.

Ultegra short cage can easily handle the 12/27.

short cage for double
long cage for triple

lickbike has this to say on the Ultegra 6600 short cage rear der.:

"Maximum front difference is 14T and total capacity is 29T. Max. cog size is 27T and min. cog size is 11T. "

http://www.lickbike.com/productpage.aspx?PART_NUM_SUB='0419-00'

Looks to be the same for the Dura-Achee part as well.

short cage for double
long cage for triple

This is the right answer.

A lot of people get confused, thinking long cage is for larger cogs. It's not true; all of Shimano's road RDs, short or long cage, Ultegra, Dura-Ace, 105, or whatever, have a large cog capacity of 27 (though you can usually push that a bit).

If you need larger cogs (32, 34) you will generally need a MTB or touring RD (most of which happen to be long-cage, but the cage is not what enables them to handle the larger cogs).

short cage for double
long cage for triple
So, can I keep using my long cage RD if switching to a double crank? I have a Race Face 53/39 that I want to install on my Trek 1500. I have purchased a 10 spd FD and will get a new chain as well.

So, can I keep using my long cage RD if switching to a double crank? I have a Race Face 53/39 that I want to install on my Trek 1500. I have purchased a 10 spd FD and will get a new chain as well.

Yes, it will be fine. Actually he should have said "long cage for double or triple"; it will handle both. But short cage will generally not handle triple, unless it's a really narrow-range triple. Cage length is about being able to take up the chain slack for the small-small combination, but also letting out said slack for the big-big combination.

Yes, it will be fine. Actually he should have said "long cage for double or triple"; it will handle both. But short cage will generally not handle triple, unless it's a really narrow-range triple. Cage length is about being able to take up the chain slack for the small-small combination, but also letting out said slack for the big-big combination.

touche

It's chainwrap that matters, not the cog size. For example, my short cage 8s didn't like a 12-28 with a 50/34 because it had too large of a chainwrap. Most short cage derailleurs seem to recommend staying under about 29. Mine was 32.

The formula according to a bike shop website:

Chain-wrap capacity = (large chainring - small chainring) + (large rear cog - small rear cog). Example: 53/42/30 chainrings and a 12-27 cassette: (53 - 30 = 23) + (27 - 12 = 15) = 38-tooth chain-wrap capacity.

Per Campy, the only cassette that requires a long cage is 13-29, all else is fine with short cage.

^ Even with a triple??? (ignoring the fact that the OP is on Shimano)

Per Campy, the only cassette that requires a long cage is 13-29, all else is fine with short cage.

Yup, campy's official position...but I've ridden campy's with short cage 13-29 no problem.

well now i'm thoroughly confused!

i started a similar thread in the mechanics sub-forum. i'm concerned about being able to use a std rival or force rd with an 11-28 road cassette. from sram's website, it looks like they don't make a long cage road rd.

for my upcoming build, i've been "operating" based upon the mfr tech docs, what i've read on sheldon brown and what i've read here.

i thought that the primary reason for needing long vs. short cage rds was to take up slack for the difference in chain length needed between the largest and smallest cogs (and the chainrings). also, i thought longer cages were needed to keep the pulley from rubbing especially large cogs. here's what i saw on sheldon brown's site;

"Road" vs "Mountain" Cassettes, Derailers and Hubs
When discussing cassettes, the terms "Road" and "Mountain" are marketing terms, not technical ones.
"Road vs Mountain Cassettes
Cassettes come in various gear ranges, and the ones where the sizes are close together, with no really large sprockets are commonly referred to in marketing-speak as "road" cassettes. Wide range cassettes, with larger sprockets are commonly called "mountain" or "MTB" cassettes.
"Road" vs "Mountain" Derailers
Similarly, derailers come in long cage and short cage versions. The short cage ("road") ones only work with narrow range ("road") cassettes, because they don't have enough capacity to take up chain slack for use with a wide range cassette. Short cage derailers are also limited in terms of the largest rear sprocket that they can clear without having the jockey pulley rub on the sprocket.
Long-cage derailers have greater takeup capacity, and work with all types of cassettes. Long-cage derailers are commonly called "mountain" derailers currently, though in the past, this style of derailer was known as a "touring" derailer. (The marketeers retired the use of "touring" as a buzzword in the late '80s when mountain bikes became the hot item.)

Note, also that rear derailers do not care how many gears you have. You do not need to have a so-called "10-speed" derailer to use a 10-speed cassette. This is true of all Shimano derailers with the exception of 1996 and earlier (pre-9-speed) Dura-Ace units.

"Road" vs "Mountain" Hubs
There is no interchangeability issue between "Road" vs "Mountain" cassettes and hubs as long as the number of sprockets matches.
Also, hubs marked "8-speed, 9-speed or 10-speed will work with any number of sprockets! (Add a 4.5 mm spacer before installing a 7-speed cassette on an 8-, 9-, or 10-speed hub.)

well now i'm thoroughly confused!

i started a similar thread in the mechanics sub-forum. i'm concerned about being able to use a std rival or force rd with an 11-28 road cassette. from sram's website, it looks like they don't make a long cage road rd.It will work fine



for my upcoming build, i've been "operating" based upon the mfr tech docs, what i've read on sheldon brown and what i've read here.
Nothing really contradictory there. It is slightly confusingly written, in particular this sentence:

Long-cage derailers have greater takeup capacity, and work with all types of cassettes. Long-cage derailers are commonly called "mountain" derailers currently, though in the past, this style of derailer was known as a "touring" derailer.
Because it suggests that any long-cage derailleur can handle any cassette, and this is definitely *NOT* the case. Try putting a long cage Ultegra, 105, Tiagra, Dura-Ace, or other "road" derailleur on an 11-34 cassette; it will not work.

It will work fine


+1

Unless your chain was cut too short...but shoud be just fine.
Take it to a good LBS and have them set it up if it's more than you wanna deal with.
If they try to sell you a Med or Long DR then find another LBS

well now i'm thoroughly confused! here's what i saw on sheldon brown's site;

Sheldon Brown has hundreds of pages on his website. It's impossible for him to keep them all updated. The reference to short cage vs. long cage and road vs. mountain rear derailleurs is an example of a reference that isn't completely accurate today.

There are 2 separate rear derailleur capacity factors: largest rear cog capability and chain wrap.

All modern Shimano road rear derailleurs are rated for a 27t big cog. Short cage derailleurs are rated for 29t or chain wrap and long cage derailleurs are rated for 37 or 38t of wrap.

Sram road rear derailleurs are rated for a 27t big cog and 31t of chain wrap. AFAIK they don't offer a long cage version.

Campy is a little different. Short cage rear derailleurs are rated for a 26t big cog and 27t of wrap. Medium cage derailleurs are rated for a 29t big cog and 36t of wrap. Campy also has long cage (triple) rear derailleurs that are rated for a 29t big cog and 39t of wrap.

As a general rule, mountain bike rear derailleurs will handle a larger big cog and a more chain wrap.

Yup, campy's official position...but I've ridden campy's with short cage 13-29 no problem.

Does the chain rub the the pulley or the frame of the derailleur when in the 29? Did you have to tinker with the adjustment screws at all? I have wanted to try the 13-29 on my bike for the steep climbs in my area and of course would only use the 34-29 combo but don't want screw up a perfectly good Chorus short cage.

I had a custom 12-29 miche cassette on my short cage Ultegra 9 speed and it never rubbed, but it didn't shift all that well either.

It will work fine



Nothing really contradictory there. It is slightly confusingly written, in particular this sentence:

Because it suggests that any long-cage derailleur can handle any cassette, and this is definitely *NOT* the case. Try putting a long cage Ultegra, 105, Tiagra, Dura-Ace, or other "road" derailleur on an 11-34 cassette; it will not work.The so-called "road" derailers are not available with long (SGS) cages. They are available with short (SS) and medium (GS) cages only.

Shimano's literature sometimes confuses things by calling the medium cages "long."

Sheldon "The Long And The Short Of It" Brown

Sheldon Brown has hundreds of pages on his website. It's impossible for him to keep them all updated. Thanks, that's true...my main site has over 2,000 pages.


The reference to short cage vs. long cage and road vs. mountain rear derailleurs is an example of a reference that isn't completely accurate today.I beg to differ here. Part of the problem was that I was quoted out of context. I reproduce the relevant paragraph from http://sheldonbrown.com/speeds below.


All modern Shimano road rear derailleurs are rated for a 27t big cog.That's because so-called "road" cassettes don't go any bigger than 27 teeth. We have sold hundreds of our 13-30 "Century Special" cassettes, almost all of them for use with so-called "road" rear derailers. In almost all cases, they work fine. A very few frames with non-standard dropout geometry require upgrading to a long (SGS) cage (so-called "mountain") rear derailer.

For more on this issue, see: http://sheldonbrown.com/capacity.

From: http://sheldonbrown.com/speeds :

"Road" vs "Mountain" Rear Derailers

Similarly, derailers come in long, medium and short cage versions. Shimano designates them: SGS (long), GS (medium), and SS (short.) The short cage ("road") ones only work with narrow range ("road") cassettes, because they don't have enough capacity to take up chain slack for use with a wide range cassette. Short and medium cage derailers are also limited in terms of the largest rear sprocket that they can clear without having the jockey pulley rub on the sprocket. Generally, SS & GS rear derailers won't work properly with rear sprockets larger than 30 teeth.

Long-cage (SGS) derailers have greater takeup capacity (http://sheldonbrown.com/gloss_ca-g.html#capacity), and work with all types of cassettes. Long-cage derailers are commonly called "mountain" derailers currently, though in the past, this style of derailer was known as a "touring" derailer. (The marketeers retired the use of "touring" as a buzzword in the late '80s when mountain bikes became the hot item.)


Sheldon "Up To Date" Brown

The so-called "road" derailers are not available with long (SGS) cages. They are available with short (SS) and medium (GS) cages only.

Shimano's literature sometimes confuses things by calling the medium cages "long."


Fair enough, but I think you see what I mean, esp. per Shimano literature. It seems many LBS crews have succumbed to this terminology, as well...i.e. anything that's not "short" is "long".

This might be useful for some. General guideline I use for Shimano rear derailleurs:

Double chainring, 27/28T or smaller max cog = SS (Short cage, "Road double")

Triple chainring, 27/28T or smaller max cog = GS (medium cage, "Road triple")

Double chainring, greater than 27/28T max cog = GS (medium cage, "MTB/Tour double")

Triple chainring, greater than 27/28T max cog = SGS (long cage, "MTB/Tour triple")

Does the chain rub the the pulley or the frame of the derailleur when in the 29? Did you have to tinker with the adjustment screws at all? I have wanted to try the 13-29 on my bike for the steep climbs in my area and of course would only use the 34-29 combo but don't want screw up a perfectly good Chorus short cage.

I had a custom 12-29 miche cassette on my short cage Ultegra 9 speed and it never rubbed, but it didn't shift all that well either.

nope didn't rub, it shifted perfectly
I didn't set it up myself so I'm not sure what was/wasn't adjusted

Okay, I ride a 50/34 double,,,,to help me out on this can someone let me know whats best, long or short Dura Ace 7800 RD and what should I use for the FD. Rear will go up to but never exceed 28t

Thanks!!!!

Will, you will probably be fine. Shimano claims the Dura Ace RD can handle up to a 27t cog and a chainwrap capacity of 29. Your set-up with an 11 cog would have a chainwrap of 27, so you're fine there. You'd be pushing the max cog recommendation by 1.

fwiw I run a 50/34 with an 11-28 and I run a long cage. The shifting is fine and now I can throw a 34 on there if I ever need to.

FWIW:
Chiming in again because I just installed another 12-28 cassette on a 50/36 using a record short cage RD. (second bike with same gearing/hardware) No interferece or shifting problems at all despite Campy's claim it won't work.

FWIW:
Chiming in again because I just installed another 12-28 cassette on a 50/36 using a record short cage RD. (second bike with same gearing/hardware) No interferece or shifting problems at all despite Campy's claim it won't work.

Shimano scenario: ultegra 6500 short cage RD, 12-27 ultegra rear cassette, 34-50 or 36-52 double up front. chainwrap = 31t

will it shift well despite exceeding the shimano chainwrap specs? Curious if anyone runs this setup or similar Shimano/SRAM.

thanks

Shimano scenario: ultegra 6500 short cage RD, 12-27 ultegra rear cassette, 34-50 or 36-52 double up front. chainwrap = 31t

will it shift well despite exceeding the shimano chainwrap specs? Curious if anyone runs this setup or similar Shimano/SRAM.

thanks
I can tell you that I destroyed a 6400 derailleur (8 speed) running a 50/34 and an 11-28 cassette when I accidentally cross shifted. Not sure when they started building in more tolerance to them.

short cage for double
long cage for triple The bike I want comes 36/46 & 12-25 with a long (mid I guess) RD. Since it
has a double in front would it be better with a short cage? I am under the belief that the shorter the
cage the faster the shifts.

http://i318.photobucket.com/albums/mm438/pobox1475/Bikes/tcx1.jpg

Per Campy, the only cassette that requires a long cage is 13-29, all else is fine with short cage.

Thankyou. I can buy a new RD now.

Shimano scenario: ultegra 6500 short cage RD, 12-27 ultegra rear cassette, 34-50 or 36-52 double up front. chainwrap = 31t

will it shift well despite exceeding the shimano chainwrap specs? Curious if anyone runs this setup or similar Shimano/SRAM.

thanks


I've run 50/34 and a 12-27 with a short cage DA rear derailleur (same wrap spec as ultegra). Set it up so the chain is barely long enough on the 50x27. The chain may be a bit slack in the small ring/small cog, but you probably won't be able to use that with a 50/34 anyhow as the chain will hit the big ring, and you shouldn't be using the extreme crossover combinations anyhow.

If you were going to use a 50/34 and an 11-28, that's pushing it too far and I'd suggest a long cage rear derailleur. For 50/34 and 12-28, I dunno. Try it and see, carefully shifting into the big/big combo by hand.

If you have the chain too short then it'll destroy the derailleur if you accidentally shift into the big ring/big cog combo. That can be a problem no matter what your derailleurs wrap spec is. When you put on larger cogs or chainrings you should always check your chain length by hand with the bike on a stand.

The bike I want comes 36/46 & 12-25 with a long (mid I guess) RD. Since it
has a double in front would it be better with a short cage? I am under the belief that the shorter the
cage the faster the shifts.

I used to fear the same, but after getting a long cage (just to be safe) I really can't tell the difference. People might tease you for it, but I have plenty of other things they'd tease me about if I switched back. :D

so i have a centaur short cage derailleur with a 50-34 front and thinking about going to a sugino xd 600 crankset 46-36-26. centaur is also 10 speed and a 13-26 and/or 13-29 cassette that i can use. said rear deraiileur will work fine?

so i have a centaur short cage derailleur with a 50-34 front and thinking about going to a sugino xd 600 crankset 46-36-26. centaur is also 10 speed and a 13-26 and/or 13-29 cassette that i can use. said rear deraiileur will work fine?

No. The 50/34 front with a 13 x 26 rear has as much chain wrap requirement as Campy recommends for the short cage RD. The medium cage is recommended if you go 50/34 front and 13 x 29 rear. To go to the Sugino crank, 46/36/26, even with the 13 x 26 cassette, you'd have more max. chain wrap requirement than the 50/34 double crank with the 13 x 29 cassette which, again, according to Campy, requires the medium cage RD. Although, keep in mind, you'd have to be doing some pretty serious cross chaining while in the small chainring for it to make any difference.

Btw, the max. chain wrap requirement is figured as follows: largest chainring minus smallest chainring plus largest cog minus smallest cog-