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  1. #1
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    short v long rear mech

    (edited a mistake re. sprocket in original post)

    Hi folks.

    I'm trying to select a group set for a new off road bike and when it comes to the drive chain it seems there's plenty to consider.

    The crankset will be XT Hollowtech 44-32-22T (FC-M760).
    From the shimano site:

    RD-M760SGS (long cage):
    Low Normal Yes
    Max sprocet 34T
    Min sprocket 11T
    Front difference 22T max
    Total capacity 44T

    RD-M760GS (short cage):
    Low Normal Yes
    Max sprocet 34T
    Min sprocket 11T
    Front difference 22T max
    Total capacity 33T


    Both the same then, except for "total capacity" which means nothing to me. Could someone enlighten me as to what this, and also "Low Normal" means? The reason I ask is that I'm wondering if a short cage will go with a CS-M760/aq (9 sprocket 11-32T hyperglide cassette), or must I use a long cage?

    I'd also appreciate anyone telling me what's meant by "external bottom bracket", and any recommendations for a bottom bracket of a quality to match an XT drive train, Hope headset and wheel hubs, Hope Mono disks.

    Many thanks for any help offered.
    Last edited by banana; 11-08-2005 at 05:21 AM.

  2. #2
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    Apologies - I should have read ajoc_prez's post on this subject below:

    Short cage vs Long cage derailleurs...

    wrrm's reply is excellent and explains almost everything, although I'm still wondering what "Low Normal = Yes" means - probably something obvious that I should be able to guess..

  3. #3
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    "Low normal" is the direction the spring design returns. A low normal spring will pull the derailler towards the larger cogs on your cassette, good for pedaling under pedaling pressure or less slipping under load.

    "High normal" is the traditional spring design. The spring pulls to the smaller cogs.

    It is debatable as to which one works better. Personally I have tried both and could use either one, but I do like the shifting under load. There is one problem that I discovered when after a season of riding with it tho. The problem is that the spring pulls the cage away from the derailler body. What happens is that the cage mounting pin and the holding screw create friction with one another and wear thru. The groove in which the pin sit in wore out on mine and made the cage loose, this created alot of miss shifts. I would have to double shift to get the derailler where I wanted it to go. I have since started riding SRAM X.0's and have been impressed. I think that the 1:1 ratio makes up for lots.
    Bikeless Rider

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