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Old 05-23-07, 11:27 PM   #1
docbluedevil
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Any success with a long cage road rear derailleur working with a 11-32 cassette?

I'm considering adding a 11-32 mtb 9 speed cassette to my cross bike to lower the gearing for some of the sustained 6-8% climbs of my local forest roads. My bike is already equipped with a D/A 9 speed rear derailleur (long cage, I believe; is there a way to tell if unsure?), a 12-25 cassette, and a 38/48 crankset. A mtb cassette would be more affordable than going to a compact crankset at this point.

I've read that the max cog is 27t for the D/A long cage der., but I've heard of rumors that people have had success with a 11-32 cassette without having to go to a mtb rear derailleur.

Anyone here successfully try this?
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Old 05-23-07, 11:41 PM   #2
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You will need an MTB cage length derailleur or and actual long cage derailleur. I don't know new shimano so I can't tell you if what you are referring to as "dura-ace long cage" is actually an MTB length cage or a medium cage.
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Old 05-24-07, 01:51 AM   #3
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Quote:
Originally Posted by docbluedevil
I'm considering adding a 11-32 mtb 9 speed cassette to my cross bike to lower the gearing for some of the sustained 6-8% climbs of my local forest roads. My bike is already equipped with a D/A 9 speed rear derailleur (long cage, I believe; is there a way to tell if unsure?), a 12-25 cassette, and a 38/48 crankset. A mtb cassette would be more affordable than going to a compact crankset at this point.

I've read that the max cog is 27t for the D/A long cage der., but I've heard of rumors that people have had success with a 11-32 cassette without having to go to a mtb rear derailleur.

Anyone here successfully try this?
27 tooth is (listed) max for a short cage (ss).
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Old 05-24-07, 02:28 AM   #4
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The cage length has NOTHING to do with the maximum sprocket the RD can handle.

Both short-cage and long-cage Shimano road RDs are intended for sprockets up to 27T, but in practice they almost always work with 30T, and sometimes even 32T or 34T - I think it depends on derailer hanger geometry and chain tension. I have a road bike with an 11-30 MTB cassette and a short-cage Tiagra RD, it works fine, but the "B-tension" screw on the RD is tightened to the max.
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Old 05-24-07, 04:01 AM   #5
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Originally Posted by mozgj
The cage length has NOTHING to do with the maximum sprocket the RD can handle.
Correct, but the cage length DOES increase the capacity.
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Old 05-24-07, 11:14 AM   #6
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The cage length has NOTHING to do with the maximum sprocket the RD can handle.
Correct, but the cage length DOES increase the capacity.
Uhhh... what?

It increases the slack capacity, not the cog size capacity.
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Old 05-24-07, 11:54 AM   #7
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DMF is right--cage length will increase capacity--of your crankset, not the cassette. Long cages are required with triple cranks to maintain chain tension with the large different between the smallest and largest chainrings.

Like someone else said, you should be able to get away with a 30 on the back with your current derailleur, you might have to crank the B screw in a ways but is should work.
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Old 05-24-07, 12:35 PM   #8
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Originally Posted by DMF
Uhhh... what?

It increases the slack capacity, not the cog size capacity.
Sorry you are wrong. I don't see where I said cog size capacity.

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Long-cage (SGS) 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.)
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Old 05-24-07, 12:52 PM   #9
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Originally Posted by john_iverson
DMF is right--cage length will increase capacity--of your crankset, not the cassette. Long cages are required with triple cranks to maintain chain tension with the large different between the smallest and largest chainrings.
The range of the cogset matters, too, when figuring chain wrap capacity. The formula for figuring chain wrap requirement is: Largest chainring teeth minus smallest chainring teeth plus largest cog teeth minus smallest cog teeth. You can get away with using a rear derailleur with less chain wrap capacity than that formula calls for if you never use the smallest chainring with the smallest cogs. Shouldn't do that anyway, it's cross chaining; but if you want a derailleur that will handle all possibilities, that's the formula-

Last edited by well biked; 05-24-07 at 01:01 PM.
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