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Thread: Moving to 2x9

  1. #1
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    Moving to 2x9

    Hello,
    I'm moving to a 2x9 (22-36-bash) setup from a 3x9 (22-32-44) on the same set of cranks by swapping rings around. My cranks are race face ride xc on my 09 trance x3

    I looking to make sure I don't screw my self with this. so I know I'll need to adjust the FD HL screw to prevent over shifting. My question is should I move spacers on my bottom bracket to adjust the chainline out a bit for bet performance and less cross chaining?

    Thanks in advance
    -Tyler

  2. #2
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    Nothing to change if the 36t middle ring clears the chainstays (it should).
    The optimal chainline should be right in between the small and the middle ring, so it will be already perfect.

  3. #3
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    Shimming your BB in 1-2mm may be necessary. Depends on your current chainline. You should be able to use ALL your gears in 2x9!

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    why in? wouldn't I shim to the right? since i'm taking off the big ring. that is if it needs shimming at all

  5. #5
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    I think you should be fine just leaving it as is.

    However, if you want to get technical: all of these modern cranksets are too far out to begin with for "proper" chainline. Chainline for a 135mm 9spd hub is only about 45mm. Modern triple cranksets are out at 50-51mm not because it shifts better but to create more room for frames with big tire clearance and to stop front derailleurs from running the side of big tire

  6. #6
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    For most chainlines, on 3x9's you set the chain dead on the middle front chainring and on the fifth rear cog. With a 2x9 you want the front to be between the small and the middle(assuming that you are removing the large chainring and either leaving it open or using it for a bash guard. You still want a dead even chain centered over the fifth rear cog. Of course you never get a perfect chainline, but you can come close.

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    Be sure to check the your front derailler as well. Some FDs can only make a 12 tooth jump (ie 24-36) and you are looking to make a 14tooth jump. What might happen is inorder to have the FD adjusted correctly to shift up to the 36t the chain will be sitting on the cage of the FD when in the 22. I would just look out for this as you are coming a setup with no more than a 12t jump.

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    Why can't they make a FD with a 14 or even 16 tooth gap? I would love a 22/38 front 2x9!

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    They do state that 12t max, but I used both a Shimano SLX and an old LX M572 with a 26/42 combo (16t jump) and never had problems. That was a hardtail though, so maybe it doesn't apply completely to a bike with rear suspension

  10. #10
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    Quote Originally Posted by BostonBoy View Post
    Be sure to check the your front derailler as well. Some FDs can only make a 12 tooth jump (ie 24-36) and you are looking to make a 14tooth jump. What might happen is inorder to have the FD adjusted correctly to shift up to the 36t the chain will be sitting on the cage of the FD when in the 22. I would just look out for this as you are coming a setup with no more than a 12t jump.
    +1. i was gonna mention the same thing. probably wont be an issue but worth a check. leave your spacing as is.

  11. #11
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    Have you checked out the Shimano M665 double and bash crankset and M665 double specific FD?

    After trying to convert my own and getting all sorts of shifting & rubbing problems, I went with the M665 and it works great...

  12. #12
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    Quote Originally Posted by Yogii View Post
    Why can't they make a FD with a 14 or even 16 tooth gap? I would love a 22/38 front 2x9!
    Shimano's SLX double-specific derailleur will handle 22/36.. That's a 14-tooth gap. Someday I want to try pushing things to a 22/38, but I haven't gotten around to making that experiment yet.

  13. #13
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    All you should need to do is remove the big ring and install the 36t middle and bash, then remove the appropriate ampount of links from your chain, that's it. Do not adjust the FD down from where it was unless you make sure that there will be clearance if it's an FS under full compression of the suspension, just do the limit screw and that's it. FYI, I run a 24/38 double, no bash, running an XT 761 FD and yes it is a bit hard shifting, but other than that it works just fine and no the chain doesn't rub on the FD cage in the smaller ring. If you're getting a new FD the 771/770 worked better than the 761, but was sold with the frame I had it on.
    Last edited by LyNx; 07-08-2011 at 06:52 AM.
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    I wish it was that simple, but I had two distinct issues when I went 22/36.

    First, the 36 chainring, being larger diameter, takes the chain higher up in the FD cage where it is narrower, so no matter how much I adjusted, it would rub one end of the cassette or the other, or both. Agree you shouldn't lower the FD, in fact you need to raise it a little, to bring the chain back into the widest part of the cage where it should be. But its a fine line - raise it too much and the chain starts to rub on the bottom of the cage when in the 22T.

    Second problem was the chain rubbing on the 36T ring when in the 22T ring, and using any of the small half of the cassette. Now, you could say that I shouldn't be using the granny and the small half of the cassette, but I like to have the full range of gears available just in case I need them.

    Thats why I ended up going for the M665 double specific cranks and FD. Being able to compare them now, the shape of the M665 36T ring and the FD cage are different, and specifically designed for a 22/36 combination, and solved both the problems above. My problems may well be specific to the FD cage and particular combinations of chainrings I was using (M660), but frankly, after spending a couple of thousand bucks on a bike, I didn't want to make do with cranky shifting and chain rubbing, so it was worth it going for the M665 cranks and FD for me....

  15. #15
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    Did you replace the middle stock ring with the same 36t ring or did you switch brands? If you switched brands and it was to a thicker ring which is designed to be used with matching rings then this could be part of your problem - i.e. Blackspire Super pro rings are 5mm thick and if you try to use them with normal Shimano rings which are only 3-4mm thick you'll run into this issue.

    When you say the lower/smaller 1/2 of the cassette, what are you talking, from the 5th cog down or lower/smaller than that? I haven't run a full 9spd cassette is years, but do run a modified 7 cog setup using 9spd cassette and I can use the full range of gears, without any issue in both rings, 24 or 38.

    Glad you got it sorted and good to know that the double specific SLX cranks will do this easily. For me though I have no issues using my normal XT M760 cranks and Blackspire Suprer Pro rings, not enough at least to warrant a crank and FD change.

    Quote Originally Posted by PerthMTB View Post
    I wish it was that simple, but I had two distinct issues when I went 22/36.

    First, the 36 chainring, being larger diameter, takes the chain higher up in the FD cage where it is narrower, so no matter how much I adjusted, it would rub one end of the cassette or the other, or both. Agree you shouldn't lower the FD, in fact you need to raise it a little, to bring the chain back into the widest part of the cage where it should be. But its a fine line - raise it too much and the chain starts to rub on the bottom of the cage when in the 22T.

    Second problem was the chain rubbing on the 36T ring when in the 22T ring, and using any of the small half of the cassette. Now, you could say that I shouldn't be using the granny and the small half of the cassette, but I like to have the full range of gears available just in case I need them.

    Thats why I ended up going for the M665 double specific cranks and FD. Being able to compare them now, the shape of the M665 36T ring and the FD cage are different, and specifically designed for a 22/36 combination, and solved both the problems above. My problems may well be specific to the FD cage and particular combinations of chainrings I was using (M660), but frankly, after spending a couple of thousand bucks on a bike, I didn't want to make do with cranky shifting and chain rubbing, so it was worth it going for the M665 cranks and FD for me....
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  16. #16
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    Hi LyNx, yes it was a chainring issue, but not about brand as I use all Shimano, more about trying to use combinations that weren't designed to work together! Shimano chainrings (at least in the deore/SLX/XT area where I am) are designed to run in specific combinations - 22/32/44 or 26/36/48 - the clearances, pins, ramps, teeth cutouts, and the front mechanism are all designed to work together in these combinations to make shifting as smooth as possible.

    So your average Shimano 36 middle is designed to work with a 26 granny (ie a 10 tooth gap), not a 22 (ie a 14 tooth gap) like I was trying to make it do! The exception to this is the SLX M665 mountain double, where it has been specifically designed to work as a 22/36 combination. The 22T ring on this is exacly the same, but the 36T ring is quite different. I've got a 'normal' Deore M510 36T and a SLX M665 36T on the table in front of me and I'll try and describe what they've done different to make it work better with a 22. Wish I was more capable with computers and could post a picture as that'd make it easy!

    Anyway, the 'teeth' themselves are the same, as are the four shifting pins. The difference is in the ramps (bulges) on the side of the chainring that help the chain up and down between the middle and the granny when you change gear. The normal chainring has one wide ramp, high up. This is what the chain rubs on when you are in the 22T and the small cogs on the back. On the M665 there is a two stage ramp, and it doesn't stick out so much, which does three things - helps the chain to shift up in stages, prevents it from overshooting the 22T on the way back down, and avoids chain rubbing on the ramps when you've got a crossed chainline from 22T to the small cogs on the back. Finally, the metal of the chainring extends further down to overlap with the teeth of the 22, to prevent the chain jamming between the 22 & 36.

    Again, I must stress that this is all specific to Shimano SLX chainrings and the particular combination of 22/36, but this is the combination the OP was thinking of using, and it must be a popular size for Shimano to design a specific variation of the SLX cranks and FD to support it.

    Is the shifting that much better to justify the expense of a new crankset & FD? Well, I'm a bit @nal when it comes to gear setup - I like it to be super smooth, and I like to have the whole range of gears available! Also, I was about to retire an old XT Hollowtech I triple on my other bike anyway, so was happy to move my SLX M660 triple to that bike, and bought the double specific SLX M665 and FD for my new bike. An alternative for someone wanting a smooth Shimano 22/36 setup and not wanting to shell out for the new cranks and FD, is to just buy the M665 36T chainring for approx. $40 - as that's where 90% of the benefit comes from in my opinion.
    Last edited by PerthMTB; 07-08-2011 at 11:24 PM.

  17. #17
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    Quote Originally Posted by Yogii View Post
    For most chainlines, on 3x9's you set the chain dead on the middle front chainring and on the fifth rear cog. With a 2x9 you want the front to be between the small and the middle(assuming that you are removing the large chainring and either leaving it open or using it for a bash guard. You still want a dead even chain centered over the fifth rear cog. Of course you never get a perfect chainline, but you can come close.
    As boomn mentioned (and I have many, many times), the chain line of most current triples is ~5mm too far outboard of the proper chain line.

    Remove the outer ring and the chain line of the resulting double is almost prefect.
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  18. #18
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    On a related note, not all 22 chainrings are the same. For ex comparing an XT (alloy) with a Deore 590 (steel) from their respective triple cranks, they have a different section that puts the teeth of the XT further away from the middle chainring. The result is less rubbing against the 36 with the smallest cogs.

  19. #19
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    thank you for all the responses, I'll try to respond to everything mentioned so far, here it goes:

    Although it would have been better to go with the SLX double crankset w/ a derailleur designed for that I didn't have the cash sitting around for that so I had to make do with what I have.

    I swapped my original raceface chainring with a truvativ trushift ring and it work well without problems. I noticed that I have quite a bit of wear on my cassette so I'm going to have to replace that soon as that is going to be causing problems rather rapidly.

    As for the chainline as many people mentioned it is just about perfect now which is great.

    For performance the shifting is a bit sluggish but not too bad. I also didn't have any problem leaving the FD where it is and just limiting the high end stop.

    Now its time to give a bit of advice to anyone that is willing to listen, do not put loctite on your bottom bracket it makes pulling your bottom bracket pure HELL The story behind that is that last year I couldn't get my bb to stop creaking so I put a lot of loctite on it because I was so furious, long story short BIG mistake.
    When I tried to put my NDS bb cup back in I cross threaded the bb a bit and had to file the shell a bit to get it to go in . I blame this on the loctite because the loctite made it so hard to take the bb cup in and out I was unable to tell the difference between crossthreading and correct installation but in the end it was still my fault and I highly recommend taking great care with the installation.

    Once again thank you for the assistance,
    -Tyler

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