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  1. #1
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    How stretched should a rear derailleur be in the big cog?

    Not sure how to explain what I'm asking for so please bear with me.

    I was looking through the AM HT thread here :The All Mountain Hardtail Thread. Post up yours.

    and I saw the RD on the black evil soveirgn that is almost parallel to the ground when in the big cog on the casette.

    The reason I ask, when I moved to 2x9 I took 2 links out of the chain but didn't go any further because my RD would be stretched/pulled further than being perpendicular to the grouond.

    So my Q is, how far forward should a RD be pulled to acheive good chain tension and how far is too far? I'd love to shorten my chain a bit more to reduce chain drop on the really choppy stuff.

  2. #2
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    As long as the chain can loop the two largest sprockets (big front, big rear, not threaded through the RD ) with an inch to spare it's long enough.

    The other gauge is to shift to big/big with the RD on and see if there's enough slack to bring the lower pulley forward or up an inch or so, meaning that there's enough slack so the chain isn't pulling the RD forward.

    Keep in mind that "B" screw adjustment changes the available slack in the chain by bring the RD down and back, so I consider the second test a better indicator than the first. Also remember that the chain also must be short enough for the RD to take up all the slack in the small/small combination.
    fb
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    The key to solving any problem is to understand and address the underlying cause.

  3. #3
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    Thanks, Francis. Did you take a gander at the bike in the link?

  4. #4
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    The chain length on the Evil is OK. If you look closely, there is roughly one inch of slack in the chain (the RD will allow the chain to expand into nearly a straight line). This is probably the shortest one could go on that bike, though.

    Also, and this is important, the chain will never have to be longer than it is shown on that bike since it is a hardtail. If that were a FS bike, the chain would be too short since it does not have enough slack to allow the suspension to fully compress. When setting chain length on a FS, it's important to deflate the rear shock so you can examine the chain with the suspension fully compressed.

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  5. #5
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    I looked at the photo and as Pedalphile agrees, you're fine as is. Given that it's 1x9 bike, I probably would have gone with a longer chain working toward the amount tat the RD can take up.

    It isn't a matter on one being better than the other, but I prefer to go with longer chains whenever possible, so I can shorten them if I damage a link. I prefer never to lengthen a chain with a splice, and in your case I leave it as and consider a longer chain when replacement time comes around.

    Enjoy the bike, and have fun playing in the snow.
    fb
    www.chain-L.com

    The key to solving any problem is to understand and address the underlying cause.

  6. #6
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    That isn't my bike in the pic but I hesitated going to a shorter chain when I went to a 2x9 but after seeing that thread, thought maybe shortening my chain would help.

    Thanks guys.

  7. #7
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    Quote Originally Posted by mnigro
    Not sure how to explain what I'm asking for so please bear with me.

    I was looking through the AM HT thread here :The All Mountain Hardtail Thread. Post up yours.

    and I saw the RD on the black evil soveirgn that is almost parallel to the ground when in the big cog on the casette.

    The reason I ask, when I moved to 2x9 I took 2 links out of the chain but didn't go any further because my RD would be stretched/pulled further than being perpendicular to the grouond.

    So my Q is, how far forward should a RD be pulled to acheive good chain tension and how far is too far? I'd love to shorten my chain a bit more to reduce chain drop on the really choppy stuff.
    Just long enough to be able to smoothly shift onto and off of the large cog.

    If your RD cage is perpendicular to the ground in the big-big combo (with any number of chainrings) you will have too much slack on the smaller cogs.
    Last edited by shiggy; 12-10-2010 at 12:36 PM.
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  8. #8
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    grassyass shiggy.

  9. #9
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    That's my bike

    I added a link to the chain as I was getting a bit of chain suck when back pedalling, it's spot on now.
    Santa Cruz Blur TRc

  10. #10
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    got a new pic of it in big+big I could see?

  11. #11
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    I don't yet I'm afraid, it's probably about 4 o'clock/55degrees now, will get a pic tomorrow.
    Santa Cruz Blur TRc

  12. #12
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    Quote Originally Posted by mnigro
    got a new pic of it in big+big I could see?
    Hey, I finished my new hardtail tonight so thought I'd take a pic of the RD for you as I was in the shed:

    Santa Cruz Blur TRc

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