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Discussion Starter · #1 ·
I have a Shimano XTR 9 speeds RD-M970 rear derailleur(short cage) and would like to use it for a XTR 9 speeds 11-34T cassette.

Is it a workable combo ? Or do I need a RD-M971 instead ?
 

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'brifter' is f'ing stupid
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I have a Shimano XTR 9 speeds RD-M970 rear derailleur(short cage) and would like to use it for a XTR 9 speeds 11-34T cassette.

Is it a workable combo ? Or do I need a RD-M971 instead ?
Max cog is 34, so that's good. Capacity is 33, so you need to figure that out.
 

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Carbon Fiber = Explode!
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When it comes to MTB derailleurs, never buy short cage.
 

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'brifter' is f'ing stupid
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When it comes to MTB derailleurs, never buy short cage.
That's just stupid. If the spec is correct for the application, why not?

'Capacity is 33'....Do u mean the front chainring max. is 33T ?
No..."capacity". The difference between the small cog/large cog + the difference between the small ring and large ring. For example:
11/34 cassette: difference is 23 teeth
50/34 compact crank: difference is 16 teeth
23 + 16 = 39 which is obviously more than the capacity of 33 for the GS short cage derailleur. You'd need the SGS long cage, which has a capacity of 43.
If you were running a single chainring you'd be fine w/ the GS and it's shorter cage, contrary to the incorrect advice provided by the other guy i quoted.
 

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Discussion Starter · #6 ·
That's just stupid. If the spec is correct for the application, why not?



No..."capacity". The difference between the small cog/large cog + the difference between the small ring and large ring. For example:
11/34 cassette: difference is 23 teeth
50/34 compact crank: difference is 16 teeth
23 + 16 = 39 which is obviously more than the capacity of 33 for the GS short cage derailleur. You'd need the SGS long cage, which has a capacity of 43.
If you were running a single chainring you'd be fine w/ the GS and it's shorter cage, contrary to the incorrect advice provided by the other guy i quoted.
Thanks for the valuable input.
Yes, I'm planning to run a single ring(28T or 32T) in the front. :)
 

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970 is Rapid Rise, 971 is regular small cog normal.

If you are sure you have a 970, then get a 970 with a longer cage, not a 971.

I use a 971 short cage on my commuter. 44/30 985 crank and 12/27 DuraAce cassette. Works great.
 
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