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  1. #1
    Rider and Wrench
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    Shimano 10spd Chainline with 3X Crankset - ???

    I recently installed an 10 speed XT 11-36T cassette, XTR SG Rear Derailleur, and XTR 980 10 speed Shifters on my bike. I opted to stick with the 9speed front derailleur and crankset, though am planning on swapping out the chain rings to a 24 or 26T on the Granny and a 36, 38 or 39 in the middle and possibly loosing the big ring- My goal being to loose the "granny" feeling and have two more useable front rings for my trails and ride style- as I only use the 22T in the two largest cogs and quickly shift back into the middle ring-

    I only have one ride on it and it functions great, actually a more positive shift feeling from the 970 series XTR- BUT when running in the middle 32T ring and the 36T big cog on the cassette I could hear the chain fighting the chainline- which was not the case when I had the 9 speed rear 11-34t cassette. Both the 970 and 980 3 ring cranksets have a chainline of 50mm (the 2X reduces slightly to 48.8) so nothing changed up front. To me the 36T on the cassette mated to the center ring is truly a "money" gear as it makes a 1X10 even more usefull...

    I have not been able to confirm it but I have heard rumor that the big cog on the 10spd cassettes is pushed in slightly toward the hub, which would do it- has anyone else noticed this? or can anyone shed some light on it?

    Thanks
    I Just wish I could ride more!


  2. #2
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    I don't know if the 36t sprocket is inboard on the hub compared to the 34t, bur in any case it won't be much. Since you prefer to use the middle with the inner rear, consider whether moving the crank inboard might make sense.

    Alternatively consider using the granny with a few more cassette sprockets vs using the middle with the innermost (check a gear chart for comparable ratios).

    One reason you might be feeling more of the effect of the chain angle is that larger sprockets shorten the distance that the chain has to make up the transverse distance, effectively making the angle greater. This is because the chain doesn't leave the sprocket at the top, but forward of it (cassette) and the larger the sprocket the further, forward the dis-engage point.
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  3. #3
    Rider and Wrench
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    Quote Originally Posted by FBinNY
    I don't know if the 36t sprocket is inboard on the hub compared to the 34t, bur in any case it won't be much. Since you prefer to use the middle with the inner rear, consider whether moving the crank inboard might make sense.
    I agree in general a 34 or 36T cog would not be more inboard but in this case I am comparing a 9 speed and 10 speed cassette-

    Moving the cranks inboard is a solid idea, unfortunately in this case the bike has a 92mm integrated BB so you can't adjust it with spacers etc...


    Quote Originally Posted by FBinNY
    Alternatively consider using the granny with a few more cassette sprockets vs using the middle with the innermost (check a gear chart for comparable ratios).
    This makes sense I just tend to prefer the middle ring- kind of a big part of even trying out a rear cassette with a 36T cog- I was not really looking for "more" gear


    Quote Originally Posted by FBinNY
    One reason you might be feeling more of the effect of the chain angle is that larger sprockets shorten the distance that the chain has to make up the transverse distance, effectively making the angle greater. This is because the chain doesn't leave the sprocket at the top, but forward of it (cassette) and the larger the sprocket the further, forward the dis-engage point.
    Valid idea - I am wondering if once the chain and derailleur pulleys are worn in if I will even feel it? Right now it is all new-
    I Just wish I could ride more!


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