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  1. #1
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    Shimano "Mountain Double" Setups

    Ive been running DH single ring setups for a while so Im kinda out of the loop on this new setup.

    Im going to be building up an all mountain bike (either a Tracer VP, or Nomad 2). I need some gearing (so cant use the guide mounts for single ring), but dont plan on needing a big 44t full 3 ring set on there.

    In stead of just making it easy on myself and getting the SLX double, I plan on running some XTR cranks.

    What I need to know is if the SLX double, and I think there is a Saint double, are simply a 22 and a ramped and pinned 36 with the special SLX or Saint front derailluer OR if there is an actual difference in the crank spider to correct the chainline for 2x9.

    Im not interested in the Sram XX stuff, so that leaves me with putting a ramped 36 on some XTR's and getting the proper derailluer to accomodate that.

    The next question is: since I do plan on running Sram derailluers, will the specific Shimano double friendly front derailluers work with a Sram shifter. I know the rears dont mesh due to the accution ratio, but I think the fronts are ok - just not sure about the special double specific ones.

  2. #2
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    Quote Originally Posted by IntenseMack10
    What I need to know is if the SLX double, and I think there is a Saint double, are simply a 22 and a ramped and pinned 36 with the special SLX or Saint front derailluer OR if there is an actual difference in the crank spider to correct the chainline for 2x9.
    A regular triple crankset with two rings and a bashguard works fine, and you do not need a special front derailleur either. A triple front derailleur works perfectly fine 2x9...been running this set up since 2003.

  3. #3
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    if you're not going to use the XTR rings, I would save some $$ and go XT or Saint
    the xtr rings are a big part of the cost and weight savings, bearings are the same and the xt spider is pretty standard
    reg deraillier is fine, although I believe the SLX cane be mounted lower, but its heavy

  4. #4
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    Quote Originally Posted by mtnbiker72
    A regular triple crankset with two rings and a bashguard works fine, and you do not need a special front derailleur either. A triple front derailleur works perfectly fine 2x9...been running this set up since 2003.
    I know it would technically work, but the bigger jump (22 to 36, rather than 22 to 32) requires the special derailluer to prevent chain drag on the derailluer. The last thing I want is to be cranking up a hill and having that annoying chain noise of it constantly dragging on the derailluer. Thats why Im investing the time to make I get it set up properly with the right parts.

  5. #5
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    Quote Originally Posted by IntenseMack10

    What I need to know is if the SLX double, and I think there is a Saint double, are simply a 22 and a ramped and pinned 36 with the special SLX or Saint front derailluer OR if there is an actual difference in the crank spider to correct the chainline for 2x9.

    .
    Don't know what the difference is, whether in the spider, arm or spindle, but the chainline for the SLX double is 46.8 vs the triple at 50mm....
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    Quote Originally Posted by IntenseMack10
    I know it would technically work, but the bigger jump (22 to 36, rather than 22 to 32) requires the special derailluer to prevent chain drag on the derailluer. The last thing I want is to be cranking up a hill and having that annoying chain noise of it constantly dragging on the derailluer. Thats why Im investing the time to make I get it set up properly with the right parts.
    I ran the
    SLX 22/36 for a little while with a regular FD and don't recall having any problems. I ended up swapping the 22 for a 26 because I simply don't need 22 with the range in 9-speed (I run an 11- 32 in back) and dropping into the granny from 36 to 22 was just too big of a change (you really need to simultaneously shift to a smaller cog when you make a ring change that large).

    I don't believe the 22/36 SLX changes the chainline. I didn't measure but I think it's the same as the granny and middle in a triple. I think the new SRAM XX 10-speed double cranks do adjust the chainline. The way I ride a double, I don't think the chainline really needs to be adjusted, because I want to run the middle ring through the full range of cogs and only use the granny with the larger 4 cogs.
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

  7. #7
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    Quote Originally Posted by IntenseMack10
    I know it would technically work, but the bigger jump (22 to 36, rather than 22 to 32) requires the special derailluer to prevent chain drag on the derailluer. The last thing I want is to be cranking up a hill and having that annoying chain noise of it constantly dragging on the derailluer.
    No, it doesn't unless you believe Shimano PR hype. I have run 22/36 with an 11-34 cassette for years with a standard LX or Deore front derailleur and it doesn't drag on the derailleur and I can count the number of times I've dropped the chain on one hand...no more than with a 22/32/44 triple set-up.

  8. #8
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    Quote Originally Posted by Bikinfoolferlife
    Don't know what the difference is, whether in the spider, arm or spindle, but the chainline for the SLX double is 46.8 vs the triple at 50mm....
    No difference, it is in the definition of chainline. Chianline is the measurement from the front-rear centerline of the frame, to the middle of the chainrings. The 'middle' of the chainrings is differerent on a 3 ring and 2 ring set-up.

    On a tripple, the chainline is the center of the mid ring. On a double, it is the point mid-distance between the two rings.

  9. #9
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    Quote Originally Posted by mtnbiker72
    No, it doesn't unless you believe Shimano PR hype. I have run 22/36 with an 11-34 cassette for years with a standard LX or Deore front derailleur and it doesn't drag on the derailleur and I can count the number of times I've dropped the chain on one hand...no more than with a 22/32/44 triple set-up.

    Agree 100%. My 'all but DH' bike has had 22/36, 22/38, and 24/38 all with a 11-32 rear, and all with a standard XT front derailleur. This has been several frames, many chains, several rings from various mfg, and several cassettes over more than 5 years.

    Many FS frames will drag the chain on the bottom crossbar on the derailleur when on the stand and the derailleur set to proper height. Fortunately your bike cannot ride without you, and your weight will sag the suspension, change the chainpath, and eliminating the rubbing.

  10. #10
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    Quote Originally Posted by davep
    No difference, it is in the definition of chainline. Chianline is the measurement from the front-rear centerline of the frame, to the middle of the chainrings. The 'middle' of the chainrings is differerent on a 3 ring and 2 ring set-up.

    On a tripple, the chainline is the center of the mid ring. On a double, it is the point mid-distance between the two rings.
    is that written in stone somewhere or just arbitrary? because it makes no sense that if I simply remove my big ring the chainline changes

  11. #11
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    If you are going to change rings anyway ditch the 22t, I have a a 36/22 on my XC bike and it's pointless. I would do 24/36 or 26/38 if I were you. Check out the stylo double crankset. I have always run Shimano but the Stylo looks like a good option...

  12. #12
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    Quote Originally Posted by greengreer
    If you are going to change rings anyway ditch the 22t, I have a a 36/22 on my XC bike and it's pointless. I would do 24/36 or 26/38 if I were you. Check out the stylo double crankset. I have always run Shimano but the Stylo looks like a good option...
    Yeah, after seeing responses here and thinking about it Ill probably go 24-36. I still need good climbing ability as my bike will be a bit on the heavy side of AM at 30ish

  13. #13
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    Quote Originally Posted by davep
    No difference, it is in the definition of chainline. Chianline is the measurement from the front-rear centerline of the frame, to the middle of the chainrings. The 'middle' of the chainrings is differerent on a 3 ring and 2 ring set-up.

    On a tripple, the chainline is the center of the mid ring. On a double, it is the point mid-distance between the two rings.

    True, but with 5mm chainring spacing, there's still a slight difference in the math...
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  14. #14
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    Quote Originally Posted by dan0
    is that written in stone somewhere or just arbitrary? because it makes no sense that if I simply remove my big ring the chainline changes
    It is not arbitrary, it is how chainline is defined. A crank's chainline is dependent on the placement of, and number of chainrings. Move or remove a ring, and the chainline moves. It makes complete sense if you think of what chainline is..the average location of the chain from the centerline of the bike. The chain obviously does not lye in the same location on a crank with a granny only vs a crank with a big ring only. If 'chainline' did not reflect this change, it would be a completely useless measurement.

  15. #15
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    Quote Originally Posted by Bikinfoolferlife
    True, but with 5mm chainring spacing, there's still a slight difference in the math...
    You are right, and I dont know why it is off, my guess would be some typo or oversight. The instal sheet lists both versions as 50mm chainline and that certainly is not correct.....

  16. #16
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    Quote Originally Posted by davep
    It is not arbitrary, it is how chainline is defined. A crank's chainline is dependent on the placement of, and number of chainrings. Move or remove a ring, and the chainline moves. It makes complete sense if you think of what chainline is..the average location of the chain from the centerline of the bike. The chain obviously does not lye in the same location on a crank with a granny only vs a crank with a big ring only. If 'chainline' did not reflect this change, it would be a completely useless measurement.

    makes sense, I think I was cofusing it with the ideal chainline

  17. #17
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    Quote Originally Posted by davep
    You are right, and I dont know why it is off, my guess would be some typo or oversight. The instal sheet lists both versions as 50mm chainline and that certainly is not correct.....
    I got my figures from the install sheets at techdocs.shimano.com fwiw. It surely is such a small difference gotta wonder why it's different...
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  18. #18
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    So the doc for the 2 ring version (FC-M665) lists info for the two ring version (M665) only . That doc lists the measurement as 46.8.

    The doc for the 3 ring verion, (FC-M660) lists the info for all versions of the crank (660, 661, 665, and 667) and shows the chainline as 50mm for all....

    ???????

  19. #19
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    Quote Originally Posted by davep
    So the doc for the 2 ring version (FC-M665) lists info for the two ring version (M665) only . That doc lists the measurement as 46.8.

    The doc for the 3 ring verion, (FC-M660) lists the info for all versions of the crank (660, 661, 665, and 667) and shows the chainline as 50mm for all....

    ???????
    I didn't even notice! I knew there was a separate instruction sheet and just looked for the 660 vs 665. Shimano has some 'splaining to do...can't have it both ways (but am more inclined to think there's no difference, can anyone who has access to one or the other verify? A quick measure of my SLX triple appears to be right at 50.
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  20. #20
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    I'm thinking the chainline confusion (on the part of shimano) on the M665 is because it isn't truly a conventional double chainring. It's really a triple with a bash in place of the big ring (as many of us have been running for years), and they probably weren't sure how to measure the chainline.
    So by the conventional chainline measurement for a double, the chainline would technically be shorter because you would be measuring to the distance between the granny and middle ring, while the 3-ring SLX crank is measured to the middle ring, even though these are essentially the same cranks.
    I think you then also need to think about how the rings will likely be used. In the case of the 22/36 SLX, the 36t ring will pretty much be used the same way (though not exactly) as a middle in a triple, so is it more confusing to show the chainline shorter than the triple or show it the same? It can probably be argued either way.
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

  21. #21
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    Sounds good to me. Isn't there also something about Shimano measures to the side of the ring? Could make for weird math with 5mm between chainrings c-c.
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  22. #22
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    Quote Originally Posted by Bikinfoolferlife
    Sounds good to me. Isn't there also something about Shimano measures to the side of the ring? Could make for weird math with 5mm between chainrings c-c.
    Yes Shimano measures to the inside of the ring while Truvativ for example measures to the middle of the ring (on triple cranksets respectively).

    That is why Shimano lists 50mm and Truvativ lists 51mm even though they are the same.

  23. #23
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    Is chainring spacing really 5 mm?

    Front derailer actuation ratio is 1 to 1, so if we take a typical MTB front index shifter and measure the amount of cable pull between 2 adjacent positions, we should also obtain the chainring spacing.

    I measured this on my Alivio combo unit I have in the parts bin, and it's more like 8 mm.

    I don't have any double or triple crankset around to measure the spacing directly. )
    26" faithful.

  24. #24
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    after reading these posts and doing some research myself it does seem to be arbitrary
    depends on where you take your measurement and which method you use.
    I can see the logic in using the average of the front rings but realistically the middle ring should be the focal point as this the ring that gets the most use whether its a 1, 2, or 3 ring setup in most cases. Isn't it better to have a perfect chainline on the middle ring and a bit off on the small, rather than it being a bit off on both?

  25. #25
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    Quote Originally Posted by trailville
    I'm thinking the chainline confusion (on the part of shimano) on the M665 is because it isn't truly a conventional double chainring. It's really a triple with a bash in place of the big ring (as many of us have been running for years), and they probably weren't sure how to measure the chainline.
    So by the conventional chainline measurement for a double, the chainline would technically be shorter because you would be measuring to the distance between the granny and middle ring, while the 3-ring SLX crank is measured to the middle ring, even though these are essentially the same cranks.
    I think you then also need to think about how the rings will likely be used. In the case of the 22/36 SLX, the 36t ring will pretty much be used the same way (though not exactly) as a middle in a triple, so is it more confusing to show the chainline shorter than the triple or show it the same? It can probably be argued either way.
    On current (triple) cranksets Shimano moved the chainline outboard from what is actually "proper" simply for tire/frame/tire clearance reasons. Removing the outer ring brings the chainline as measured between the two remaining rings back to near perfect.

    Overall a 1mm chainline difference is meaningless.
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