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Discussion Starter · #1 ·
I built up a Felt frameset for my (now 15-year-old) son about 18 months ago. I installed a triple because I thought he would need one. He has really come along and now never, ever uses the small ring. I'm picking up double parts to convert it to a standard double.

Here's the question: 105 short cage derailleurs are going for more than I want to spend right now, so I've got the crank, front derailleur, and will have the bottom bracket soon. What's the disadvantage of running the long cage derailleur for awhile while I await a good deal on a short cage?

Thanks.
 

· NeoRetroGrouch
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Qstick333 said:
I am running a long cage on a compact since I had one laying in my parts drawer. Maybe slightly slower shifting - although I NEVER notice, and a drop of weight. Works perfectly. Since you have it already, use it.
Why would it possibly be slower shifting? - TF
 

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Hmmm.... I think you can use a long cage on a double but you can't use a short cage with a triple...should be no problem..the long cage just allows more chain, shifting might be a tad slower (maybe)..I'm exactly sure, I've never used a triple...
 

· NeoRetroGrouch
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DavidsonDuke said:
I think the idea is that the shortest chain length and derailleur that will fit freewheel/crank will have less flex/play and will shift more crisply.
Think about it. If the cage does flex, what's out at the end of that cage? The idler pulley. What does the idler pulley have to do with shifting? Nada. - TF
 

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DavidsonDuke said:
I think the idea is that the shortest chain length and derailleur that will fit freewheel/crank will have less flex/play and will shift more crisply.
I find just the opposite. I am running an xtr sgs (long cage) on my triple and I think it shifts better than my dura ace gs (medium cage). Maybe that mountain rd has a stronger spring.

TT
 

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I have limited experience, but I have had some problems fitting long cage FDs onto compact chain rings when the large ring tooth count dropped too much lower than the original. Just a few teeth difference can jam the rear of the cage into the chainstay when you try to lower it the correct height.
 

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I'm not sure about a long cage, but I'm running a medium cage LX derailleur with a compact double (to allow the use of a 11-32 cassette when needed) and it shifts just the same as the short cage Ultegra it replaced...even on a road cassette.
 

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????

There is not such thing as a "long cage" FD. If you drop the height of a FD by 6mm for a 50T chainring and the lower end of the FD cage hits the chainring, it means the seat tube angle is to blame. In this case it's too slack. FD's must fit a range of STAs, from 75 to 72. All you can do with a clamp-on FD is set the height so it clears the big ring.

What I do is use a clamp-on adapter with a braze-on FD. I usually have the opposite problem, with a 74.5 degree STA, the FD will fit fine, but lower end of the cage is higher than it needs to be. I use a dremel sanding drum and alter the angle on the clamp-on adapter, so it matches the curve of the big ring.
 

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C-40 said:
There is not such thing as a "long cage" FD. .
All I know is what I have seen, I'm probably just using the wrong terminology. Some FDs have a longer cage than others. When the front chainring is 48 teeth or larger, the mounting point of the FD is higher and it clears the chainstay. On a chainring of 46 or so, the only way to clear the chainstay is to mount at a point much higher than what is considered correct. Some FDs are shorter so they fit; some are identified as compact. Of course the angle of the frame is part of the problem, but I cannot blame the frame when there are parts available that will work around it.
 

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Discussion Starter · #14 ·
There are double and triple front derailleurs, but I've never heard them called long or short cage, only rears.

According to the description of the latest Campag Super Record Carbon rear derailleur, the stiffness of the rear derailleur affects how quickly/crisply it shifts. That would be an argument for a short rear when possible: http://velonews.com/article/77895/tech-report-the-campagnolo-11-speed-super-record-group I'm sure there's no marketing hype in such a report.

I'll happily keep the long-cage for my son's bike, though.
 

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You are using the wrong terminology. FDs do not have long, medium and short cage versions.

The phenomena you are describing has to do with standard vs. compact specific FDs. Its not the frame's fault and its not any FD's fault either. Its the result of using components that were not designed to work together.
 

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Marketing hype or not, Campy does not claim any connection between RD stiffness and cage length.

velonews said:
Rear derailleur rigidity is one of the factors that translates into snappier, more precise shifting. Campagnolo increased the rigidity of its 11-speed rear derailleurs by redesigning the parallelogram and the carbon fiber front link, a piece that is said to be 150 percent stiffer torsionally than its 10-speed predecessor.
 

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Discussion Starter · #17 ·
PeanutButterBreath said:
Marketing hype or not, Campy does not claim any connection between RD stiffness and cage length.
True. But with metal derailleur cages at least, wouldn't the longer cage be the more flexible? Thus if RD stiffness increased shifting quality, one would, all other things being equal, prefer a shorter cage, right?

I'm not trying to make a case, just to work out why some might think it matters.
 

· NeoRetroGrouch
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DavidsonDuke said:
True. But with metal derailleur cages at least, wouldn't the longer cage be the more flexible? Thus if RD stiffness increased shifting quality, one would, all other things being equal, prefer a shorter cage, right?

I'm not trying to make a case, just to work out why some might think it matters.
No, because that's not where the stiffness matters. All the cage, with the idler pulley, does is take up slack chain. The front pulley does the shifting. - TF
 
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