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  1. #1
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    Need new derailleur - long cage or mid cage?

    Just want to check which cage length derailleur I need for my Trance X0 2012. The old (now broken) one only has the model RD-M780 marked on it. Its an XT Shadow 10 speed derailleur for a 11-36T casette and 26x38 front chainring. It's just the stock Trance arrangement. I don't know why they cant just mark this sort of stuff on it or have a different model number

    Thanks

  2. #2
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    first you're in the wrong section.. go over to drive train...


    and, there is a sticky post there that show you how to figure it out.. pretty simple math
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  3. #3
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    you need a long cage with the 36T. A mid cage would only get you up to a 30T. I have a mid XTR on my Cross bike with a 30T. I think if I remember when borrowing a wheel the 32 was getting too close to the jockey wheels even with the B screw turned in all the way

  4. #4
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    Hi bro, you definately need the long cage derailleur , i ride 2012 trance x1 which uses the same rear derailleur as xo.

  5. #5
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    Really, that's your honest opinion and you're sticking to it? A mid cage RD will work just fine with even up to a 36t cog, the problem lies in it taking up enough of the chain slack in bad gear combos since there's such a big jump in the front rings, but in no way, shape or form will you have trouble with keeping the upper pulley off the cassette cogs He is right that a long cage would work better if you insist on using all gear combinations, if you however don't do that a mid cage could work just fine.

    Quote Originally Posted by oberwil View Post
    you need a long cage with the 36T. A mid cage would only get you up to a 30T. I have a mid XTR on my Cross bike with a 30T. I think if I remember when borrowing a wheel the 32 was getting too close to the jockey wheels even with the B screw turned in all the way
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  6. #6
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    If you are just trying to determine the cage you have now - my SLX long cage is 100mm between the jockey wheel bolts and my medium cage is 80mm.
    If you are trying to determine what you need - you need to take up 37 teeth of chain. Shimano medium derailleurs are only rated for 35 teeth. On a hard tail I'd go with the medium anyways but since you have a FS, I'd say the long cage would be safer - the suspension movement may require additional chain take up capacity.

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