2011 Sram X9 rear derailleur short cage hitting cogs

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2011 Sram X9 rear derailleur short cage hitting cogs
Author Message
flag YetiSuperX
Posted: Oct 17, 2011 at 16:02 Quote
Running 11-36. I'll give it a go again and see what happens.
flag Nobble
Posted: Oct 17, 2011 at 17:41 Quote
YetiSuperX wrote:
Running 11-36. I'll give it a go again and see what happens.
what cage? a short or medium wont work...
flag YetiSuperX
Posted: Oct 17, 2011 at 17:48 Quote
The thread is about small. So i'm running small. And it's running smoooooooooooth
flag Nobble
Posted: Oct 17, 2011 at 17:49 Quote
there's your problem...
flag YetiSuperX
Posted: Oct 17, 2011 at 17:50 Quote
Huh? According to Sram I'm way within the limits. What's your point?
flag Nobble
Posted: Oct 17, 2011 at 17:54 Quote
YetiSuperX wrote:
Huh? According to Sram I'm way within the limits. What's your point?
a short cage mech can only cover a certain range of gears...

the 36 is too big for it (unless you meant 26)
flag YetiSuperX
Posted: Oct 17, 2011 at 17:56 Quote
11-36 have a span at 25. This is within the limits of the Sram small cage. Long cage for 1x10? You must be bonkers Wink
flag Nobble
Posted: Oct 17, 2011 at 17:58 Quote
YetiSuperX wrote:
11-36 have a span at 25. This is within the limits of the Sram small cage. Long cage for 1x10? You must be bonkers Wink
if you say so...

I'd almost be willing to bet that it would go away if you ran a smaller cassette like an 11-28 though...
flag YetiSuperX
Posted: Oct 17, 2011 at 18:00 Quote
On an AM bike? Don't think so. The problem isn't about the cage size while running with chain. It's just when there isn't a chain it slams the cogs. Not the 36 cog but some of them in the middle.
flag Mattynf
O+
Posted: Oct 17, 2011 at 19:14 Quote
Yet another case of misunderstanding derailleur capacity. The capacity of a derailleur has nothing to do with what size cassette you can put on the back specifically, but what combination of cassette and crank can be used. The capacity of the derailleur is controlled by the length of the cage, and is a measure of how much chain slack the derailleur can pick up. This is why people generally go short cage for single rings, mid cage for doubles and long cage for triples. The longer chain needed to accommodate the jump from a granny ring to a big ring needs to be taken up by the derailleur cage.

Now moving on to max cog. This is controlled by the size of the derailleur body itself, not the cage length. All Sram X9s, regardless of cage length, are suitable for 36t cassettes. Moving to an 11-28 cassette would do nothing to help his problem, and that is a foolish cassette to put on anything other than a downhill mountain bike.

nf99 wrote:
I don't remember ever having this issue with 9 speed and the issue is remedied once the chain is routed and the cage has tension holding it in position. If a chain were to break, it would be a real PITA, as it surely would mangle the derailleur cage.

You will not mangle the derailleur cage. As soon as the chain breaks the cassette stops spinning (unless you're riding in reverse). Chains break above the effective chainstay moving forward because this is the direction where they take your drive forces. When the chain breaks, even if you keep pedaling, you will just run the front half of the chain around your crankset until it falls off, while the derailleur just pins the chain up against the cassette, and the cassette starts to freewheel. Just set up your b-tension in the ideal position with a proper length chain installed on your bike.
flag theminsta
Posted: Oct 17, 2011 at 19:26 Quote
I had this problem with both the 10-sp, short cage X9 derailleur and the 9-sp, short cage X7 derailleur. The cage hits the cassette when at the highest/smallest gear; it's not like the derailleur rams into the cassette as it gets shifted up.....

As for the b-limit screw, pushing it too far means substantially decreasing the amount of chain-wrap the chain has on the cassette. What do you think about that?
flag ArmyFork
Posted: Oct 17, 2011 at 20:42 Quote
The chain wrap engages plenty of surface area, the largest load in such situations will be within the first three teeth with the remaining carrying very little actual load.

A short cage works fine on an 11-36, I've ran both short and longs on those cassettes, the cassette should not be an issue. The only time you really need a long cage is if you're running a three ring front, with the largest ring being over 40t as per usual.

Should say props to Mattynf, everything he said is bang on.
flag nf99
Posted: Oct 18, 2011 at 15:55 Quote
Mattynf wrote:
You will not mangle the derailleur cage. As soon as the chain breaks the cassette stops spinning (unless you're riding in reverse).

.....great point and one i embarrassingly enough overlooked completely.
flag YetiSuperX
Posted: Oct 19, 2011 at 6:20 Quote
nf99 wrote:
Mattynf wrote:
You will not mangle the derailleur cage. As soon as the chain breaks the cassette stops spinning (unless you're riding in reverse).

.....great point and one i embarrassingly enough overlooked completely.

That makes two of us.
flag ArmyFork
Posted: Oct 19, 2011 at 7:05 Quote
YetiSuperX wrote:
nf99 wrote:
Mattynf wrote:
You will not mangle the derailleur cage. As soon as the chain breaks the cassette stops spinning (unless you're riding in reverse).

.....great point and one i embarrassingly enough overlooked completely.

That makes two of us.

Weirdly even that skipped my mind, I've worked on enough drivetrains you'd think I'd remember. Brain skipped a beat

 


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