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  1. #1
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    ETSX and SRAM XO B temsion ???s

    I am installing an XO rear derailleur from an XTR on my Rocky Mountain ETSX. The instructions says move the derailleur to the largest cog in the rear and set the gap to 6mm (or 1/4") then move the rear derailleur to the smallest cog and check the gap which should be the same 6mm. When I get the gap on the largest cog to 6mm then move to the smallest cog it is now about 13mm (or 1/2") gap. I can not get the consistent gap that the instructions call for, and if I get the gap at 6mm on the smallest cog it will rub on the largest. Has anybody else got the gap correst on the largest and smallest cog with their SRAM?

  2. #2
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    I'm no expert about this. Barely even a neewbie, but I was just doing some research about converting my XT rear to an X9 or XO.

    What shifters are you using?

    If you are using your XTR shifters, you might need to switch to SRAM. I'm not sure yet, but I think the SRAM is a 1:1 ratio, and the Shimano is not.

    I get the impression that this is why there are a few random bad reviews for SRAM stuff in the product review section. People using the wrong shift pods, and can't get it adjusted properly, while for others it's really easy and never fails.

    Or, could it be the cage length or number of teeth in your cassette are different from what they spec it to? In other words, a 6mm gap is you are running 12-24, but you have an 11-26 cassette?

    My XT rear is a good 5 years old, and my pods are like 7-8 yeras old. So I'm thinking of getting new stuff, but am still trying to figure this out. So I'll be looking to see what other responses you get.

  3. #3
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    My shifters are SRAM XO, but I did get an answer to the B-tension question.

    I called SRAM today and that is what they said as well to just set it by the largest and not worry about the other cogs. When I looked closer to the example in the instructions they were using an 8 speed cassette in the illustration.

  4. #4
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    In a perfect world...

    Quote Originally Posted by Aaron65
    My shifters are SRAM XO, but I did get an answer to the B-tension question.

    I called SRAM today and that is what they said as well to just set it by the largest and not worry about the other cogs. When I looked closer to the example in the instructions they were using an 8 speed cassette in the illustration.
    ....the dimensions and orientation of the hanger would allow the upper pulley to maintain a consistent distance from each cog, but the hanger, derailleur and a given cassette would have to be designed specifically for each other in mind. Often the B-tension is simply adjusted such that the upper pulley is as close as possible to the largest cog without contacting it when pedaling forwards. Often back pedaling will make the upper pulley contact the largest cog when forward pedaling will not, which isn't a problem. Proper chainlength is also critical for proper tracking of the upper pulley, as it rotates off-center around the cage pivot as the cage moves to take up or give more slack to the chain.

    -R

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