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  1. #1
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    Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD

    Posting this to show a recent mod that I did to my front derailleur (FD) to address the fact that it was digging into the lower link on my 2012 Mojo HD (with bolt on FD).

    I essentially shaved off some of the metal on the backside of the derailleur to give more room between it and the link. I spent a couple hours trying to adjust the FD height, high/low settings, and cable tension with no success.

    The photos show my old, black link and where it was damaged and then the work I did on the FD before installing my new blue link. They're not the best photos but hopefully you get the idea and hopefully it helps.

    DISCLAIMER - There may be other solutions. This is just what I did .
    Attached Thumbnails Attached Thumbnails Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD-img_4910.jpg  

    Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD-img_4913.jpg  

    Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD-img_4916.jpg  

    Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD-img_4918.jpg  


  2. #2
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    yeah, did exactly same thing with mine, same XT FD, in fact several people did. when i emailed ibis they told me it was stacking tolerances issue.

  3. #3
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    Fassn8,
    Could you post a picture from the side, with rings on? I'm curious how low you have adjusted the FD. I'm particularly interested in this and whether this would work with my 24/36/bash setup. Would like to try and adjust the FD lower than it is now, but link is in the way.
    Thanks,
    Mike

  4. #4
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    here you go
    Attached Thumbnails Attached Thumbnails Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD-img_4925.jpg  

    Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD-img_4926.jpg  

    Modified Front Derailleur to prevent Lower Link damage on 2012 MOJO HD-img_4927.jpg  


  5. #5
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    My local shop just moved the small spacer on the BB over to the right side, so now there is 2 on that side, No more hitting and it was way easy. It moved everything over just enough to have clearance.

  6. #6
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    I already have two spacers on that side and one on the other.... hmmm...

  7. #7
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    Just had the same issue when I changed my crank from a 2 x10 SRAM X0 to a race face Sixc 2 plus bash.

    The primal mech was a 2 x 10 and it wouldn't shift down enough to the small ring so.

    I purchases a 3 x 10 mech and it just clears ok now

  8. #8
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    I would be worried to move the spacers over on the BB as this would lower the thread engagement on that side

  9. #9
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    I believe you're suppose to have 2X2.5mm spacers on the drive side and 1X2.5mm spacer on the other side.

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  11. #11
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    Yup. That's how mine is set up. Again, I've got an XT setup.

    shaving down the affecting area of the FD solved the problem. Plenty of room now and was very easy to do.

  12. #12
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    did a similar thing on my XTR 3x FD on my old Mojo. no issues on my HD with a X0 2x FR/cranks though.

  13. #13
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    I just noticed I have this issue on my newly installed red links but didn't have this problem on the black links that came on the bike originally. Wish I would have known about this before I installed the new links.

    Oh well, time to get out the angle grinder.

  14. #14
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    Red and Blue sharpie's do a decent job at covering up the scratches.
    Rode my new links today and shaved FD. WAY faster

  15. #15
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    Is this problem only on HDs or is it on regular Mojo's also?

  16. #16
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    Quote Originally Posted by camp343 View Post
    Is this problem only on HDs or is it on regular Mojo's also?
    My regular Mojo with 3x9 (noir cranks, XTR FD) had that grind until I shaved the FD - might have been after I adjusted the low screw to get better shifting into granny though. My HD with 2x10 doesn't show issue.

  17. #17
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    New question here. maybe a silly question...

    Quote Originally Posted by brankulo View Post
    when i emailed ibis they told me it was stacking tolerances issue.
    But WTF are are "stacking tolerance issues" ?
    - -benja- -

  18. #18
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    And why are there stacking tolerance issues on a $2,600 frame?

  19. #19
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    New question here. Anyone else seeing this on XO 2x setups?

    Quote Originally Posted by adumesny View Post
    did a similar thing on my XTR 3x FD on my old Mojo. no issues on my HD with a X0 2x FR/cranks though.
    So far one person who says they don't have this issue with SRAM XO 2x.... Anyone else?

    I'm getting a tiny bit of contact on on my XT 3x setup. Will likely grind it this weekend, but was also looking into making the switch to SRAM 10spd (XO 2x) at some point...

    Hmmmm...
    - -benja- -

  20. #20
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    Quote Originally Posted by pwd81 View Post
    And why are there stacking tolerance issues on a $2,600 frame?
    Stacking tolerances is exactly that, both parts are in tolerance, but between the two of them, you get a nasty fit for whatever reason. Ibis has no control over Shimano's production line. and strictly speaking, you can't fault either company. Both parts are in spec, it's just bad luck of the draw I suppose.
    Save the Earth, Ride a Cyclist

  21. #21
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    the frame is now $2600? holy crap

  22. #22
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    I nudged my XT up a bit...

    ...and now it's fine. Shifting seems fine too. Not sure why the shop had originally put it so low to begin with, but it seems like it didn't need to be.

    Will be riding it a lot this weekend so I'll confirm.
    - -benja- -

  23. #23
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    Quote Originally Posted by benja55 View Post
    So far one person who says they don't have this issue with SRAM XO 2x.... Anyone else?

    I'm getting a tiny bit of contact on on my XT 3x setup. Will likely grind it this weekend, but was also looking into making the switch to SRAM 10spd (XO 2x) at some point...

    Hmmmm...
    I haven't had an issue with my front derailleur and link on my 2012 HD...

    Cranks: 2012 X0 GXP 2.2 10-SPEED 175mm 39t/26t
    Der: 2012 XT Direct Mount Front Der

    Best pix i've got of that area...





    *3o3

  24. #24
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    No issue for my '12 HD w/XX 166q, 28/39 cranks and both the XX and XT 2x FD's.

  25. #25
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    Quote Originally Posted by b4 stealth View Post
    Stacking tolerances is exactly that, both parts are in tolerance, but between the two of them, you get a nasty fit for whatever reason. Ibis has no control over Shimano's production line. and strictly speaking, you can't fault either company. Both parts are in spec, it's just bad luck of the draw I suppose.
    Every part is made and designed to be a certain size but because nothing is perfect they also specify a range of sizes (or tolerance) within which a part is acceptable. When you have two or more parts next to each other their tolerances add up, or stack.

    I don't see how you can't blame someone. CAD software (as well as paper and pencil) does stacking tolerance calculations. So assuming everything is within tolerance as they say, they knew this would happen. This really just means it was a poor design and they didn't care if some (hopefully small) percent of customers experienced this issue. Presumably they felt the design necessitated taking this risk which makes you wonder why they didn't take the initiative and make their part, the link/frame, to a tighter tolerance. Maybe it was just too expensive.

    If its out of tolerance it's also someone's problem.

  26. #26
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    I'm having the same issue on my XTR M981D..Nice to see others w/ similar issues and proposed solution. Going to give it a try.


    UPDATE- used my Dremel to file the corners. I was having problems shifting from middle to small ring. It needed a 1/2 more turn out on the low-stop screw but doing so, the top pivot ooint on the FD would hit the seat tube and the bottom cage would hit the lower frame link. By filling the corners allowed me adjust everything to get it shifting properly.
    Last edited by nsxtc; 12-09-2012 at 11:55 PM.

  27. #27
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    I bought an SL-R that was set up with Shimano 38-26 and was wondering why the right hand side crank arm was so scratched up. Last owner was running FD artificially high to clear the lower link which let the chain fall off. So, I thought I could clearance the FD as described here; notching the front edge of the FD cage. That mod let it clear the forward pivot end of the lower link but the FD still hits the rear portion of the lower pivot; take the air out of your shock and check!! So, basically there's no solution so I'm looking for a Race (985) 40-28 crankset to replace my (980) Trail 38-26.

    Hope this information helps someone -- trust Ibis's recommendations: Front Derailleur Compatibility | Technical Articles | Support | Ibis Cycles US

  28. #28
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    I got a FC-985 (Race) 40-28 crankset and installed it. I still couldn't lower the front derailleur low enough to get 1-2mm of clearance between the cage and the tallest chain-ring tooth. The derailleur still fouled the rearward portion of the lower link at full shock compression; it was, however, alot closer to being right than previously with the 38-26 crankset. I ran it high but dropped chain off the outside so I ground off about 2mm from the offending portion of the front derailleur. I really can't grind any more without ruining the derailleur in this area as it's the area that keeps the torsional spring positioned and rotationally locked. I'm hesitant to grind the link itself so I left it and have just about 1mm FD cage to chain-ring clearance now.

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