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  1. #1
    Wanderlust burtonridr's Avatar
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    Which Rear derailer?

    I have a Trek 820 Mountain bike with a busted ESP Sram x-7 rear derailer. I have never had to replace a derailer before.... Can I replace it with any other derailer that is for 8 gears? I dont want to spend a ton fixing it, so what are my cheaper options?

  2. #2
    Elitist Troglodyte DMF's Avatar
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    Dérailleurs don't have "speeds"; all that is handled by the shifter. You'll need to match the cage length and maximum cog size, but otherwise [see below]


    Edit: Learn to check out the part number when OP gives it.
    Last edited by DMF; 08-25-08 at 10:35 AM.
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  3. #3
    Wanderlust burtonridr's Avatar
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    Quote Originally Posted by DMF View Post
    Dérailleurs don't have "speeds"; all that is handled by the shifter. You'll need to match the cage length and maximum cog size, but otherwise just about anything will work.
    How do I determine the cage length and maximum cog size?

  4. #4
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    The question holds a mysterious snag - the Sram ESP derailleurs are, I think 1:1 actuation ratio and can only be replaced with another 1:1 actuation ratio derailleur - basically any SRAM MTB derailleur. A shimano (or sunrace or suntour or other) derailleur will not work as they are designed for 2:1 ratio shifters!

    8 speed bikes work great with 9 speed derailleurs, though... I don't think 9 speed bikes work as well with 8 speed derailleurs.

    Keep in mind I have never owned a Sram derailleur, so I am not 100% sure. A bike shop will be able to tell you if this is correct.

  5. #5
    Elitist Troglodyte DMF's Avatar
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    Ooops. Right you are. Forgot about those odd-ball SRAMs. The X-7 is 1:1. Here's the link.

    burton, you'll have to replace it with another 1:1. SRAM X-5 would do as well.

    Are you sure the old one can't be fixed? pics?
    Last edited by DMF; 08-25-08 at 10:36 AM.
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  6. #6
    Wanderlust burtonridr's Avatar
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    Quote Originally Posted by DMF View Post
    Ooops. Right you are. Forgot about those odd-ball SRAMs. The X-7 is 1:1. Here's the link.

    burton, you'll have to replace it with another 1:1. SRAM X-5 would do as well.

    Are you sure the old one can't be fixed? pics?
    LOL no it cant be fixed... It was crashed hard, the derailer was snapped off and bent the crap out of it


    So do I need to pay attention to the cog size and cag length or can I just replace it with any SRAM with 1:1 ratio?

  7. #7
    Wanderlust burtonridr's Avatar
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    can I use like a shimano Altus or something? click here

  8. #8
    Senior Member demoncyclist's Avatar
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    No, it HAS TO BE another SRAM derailleur with a 1:1 pull ratio.
    DEMON

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  9. #9
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    Quote Originally Posted by burtonridr View Post
    can I use like a shimano Altus or something? click here
    No you cannot use a shimano derailleur - sram ESP 1:1 shifters will not work properly AT ALL with a shimano derailleur. It'll make the derailleur move, but every Sram shift will move the derailleur approximately twice as far as you want it to, and not hit the gears correctly - your 8 speed drivetrain will turn ito a poorly functioning 4 speed (although it will probably only line up reasonably well in one of those four speeds)

    If you had an X7 then an X5 or another X7 should bolt right into place - and any mtb derailleur will work on your mtb gear range ... you don't really need to worry about the specifics unless you are getting something more exotic, like a short cage derailleur, or you have done some odd modifications to your cassette.

    Here's something fromt he same source:

    http://www.universalcycles.com/shopp...0&category=692

  10. #10
    Wanderlust burtonridr's Avatar
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    Ok thanks for the help everyone, I will go buy either the SRAM x-5 or x-7

  11. #11
    Wanderlust burtonridr's Avatar
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    Wait, ok so will this one work?

    Click Here

  12. #12
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    Quote Originally Posted by burtonridr View Post
    Wait, ok so will this one work?

    Click Here
    ROTFL

    "may not be exactly as pictured"

    The derailleur as described will work, the picture is of a different derailleur that will not work. But if they ever have the derailleur in the picture listed for $35, let me know right away...

  13. #13
    Wanderlust burtonridr's Avatar
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    Quote Originally Posted by LarDasse74 View Post
    ROTFL

    "may not be exactly as pictured"

    The derailleur as described will work, the picture is of a different derailleur that will not work. But if they ever have the derailleur in the picture listed for $35, let me know right away...
    Great thanks for the help

  14. #14
    Elitist Troglodyte DMF's Avatar
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    Btw, if it was crashed that hard the hanger (what the RD bolts to) will surely be bent. It has to be straightened (or replaced) or the new RD won't work worth a damn and might even catch in the wheel. Your LBS will have a tool to make it square, or with a little research you can do it yourself.
    Stupidity got us into this mess - why can't it get us out?

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  15. #15
    Wanderlust burtonridr's Avatar
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    Quote Originally Posted by DMF View Post
    Btw, if it was crashed that hard the hanger (what the RD bolts to) will surely be bent. It has to be straightened (or replaced) or the new RD won't work worth a damn and might even catch in the wheel. Your LBS will have a tool to make it square, or with a little research you can do it yourself.
    Actually.... crap the hanger might be what is broken and the derailer is bent

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