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  1. #1
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    One FS takes 11-40T easily, the other doesn't. Need advice

    I have a 2015 Breezer Repack and a 2015 Saracen Kili Flyer. I have always run the same drive train setup on both bikes (1x10 using 32T oval crank rings, 11-36T cassettes and Shimano RD-M781 derailleurs).

    I decided to freshen up my drive train components with new chains, same spec oval crank rings but 11-40T cassettes this time. The Breezer took the updates easily, but the Saracen will not shift onto the 40T ring. I have installed a Wolf Tooth Goat link and longer B screw, but it makes no difference. The only way I can get it to shift to the 40T is to remove the 17T and put a spacer behind the cassette, running it as a 1x9.

    What am I missing here? The derailleur hanging components do not appear to be bent, but I can clearly see the jockey wheels are not lining up with the 40T with the low gear stop setting all the way out.

    Is there a fix or am I stuck with either an 11-40 1x9 or an 11-36 1x10?

    Thanks
    >>"Every chance I get!"

  2. #2
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    Reputation: frdfandc's Avatar
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    Have you manually pushed the RD up to the 40T without the cable attached? And made sure that the shifter was fully let out?

    If not, do that first. If it does move manually, then it's a cable/shifter related issue.

  3. #3
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    Yes, I have pushed the derailleur with the cable disconnected. It takes more pressure than I'm comfortable with to get the jockey wheel to line up. That made me think the hanger might be bent, but that thing is so hefty it looks like it would break before it would bend.
    >>"Every chance I get!"

  4. #4
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    Quote Originally Posted by damnitzhym View Post
    Yes, I have pushed the derailleur with the cable disconnected. It takes more pressure than I'm comfortable with to get the jockey wheel to line up. That made me think the hanger might be bent, but that thing is so hefty it looks like it would break before it would bend.
    Cable disconnected, limit screw fully loosened, and it's hard to push? I'd say something is bottoming out somewhere in the RD, can't think of anything else.
    Might be kind of obvious but I would push the RD again as far as possible and inspect it very closely with a flashlight.

    Maybe the hanger design is so differet that the RD can't move inboard as far as it should. But that's just a guess since I can't see the thing IRL.

  5. #5
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    Forgot to refresh before reply, sorry

  6. #6
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    Quote Originally Posted by HollyBoni View Post
    Maybe the hanger design is so differet that the RD can't move inboard as far as it should. But that's just a guess since I can't see the thing IRL.
    This is what I'm worried about. I emailed Saracen. I'm hoping for a dropout update that addresses this, but now that they use BOOST spacing I fear there may not be any 12x142 support.
    >>"Every chance I get!"

  7. #7
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    I did some test runs with the M781 and a friend did run the M786 with an 11-42 cassette for some time.
    We didn't encounter any problems with shifting to the 42t cog on a 10s cassette.
    Maybe your derailleur is damaged, did you swap the two to see if the problem persist?

  8. #8
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    So Saracen responded with "the M781 derailleur is spec'd for a 36T max cassette" and won't travel far enough for a 40T on their bike. All 10 speed XT derailleurs on Shimano's website are 780 series and all say max cog 36T.

    I'm going to assume mine is damaged and replace it with another M780 series, most likely a M786
    >>"Every chance I get!"

  9. #9
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    Sorry if this is the ghetto approach but: take a pair of vise grips, and pull on the shift cable hard, but not hard enough to strip the cable on the shifter end, tighten cable, then shift up to the 40t ring. You may lose the 11t gear because the cable is so tight. If you get it right all gears should work, or you may skip a middle gear but at least have the lowest and highest gear and most in the middle.

    I'm doing this right now with 11-40t 8-speed cassette and 9-speed SGS rear derailleur. I explained it to the LBS today and they were like...uh...OK whatever works for you dude. They never heard of 40t with less than a 10-speed rear derailleur. I could not get an extender hooked on to the derailleur because my hanger is too big, so I did it this way instead. 36t max derailleurs can and will take 40t if the shift cable is pulled hard enough, just be careful you don't strip/break anything.
    From Ancient Times - Scarlet Skies Burn to Ash

  10. #10
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    Maybe chainline... how about a Wolfcage or One Up replacement cage? Might inly be for 11spd but check their websites for my sonís DB Splinter 24, I took an SLX 10sp RD with Goatlink and tried a 11-40 which works great. However, with a 42 I had trouble with the. middle range of gears, and so did my LBS mechanic, so we went back to 40T for him. Putting on a 26T chainring helps compensate for the low end, but it sure was strange.

  11. #11
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    Quote Originally Posted by damnitzhym View Post
    So Saracen responded with "the M781 derailleur is spec'd for a 36T max cassette" and won't travel far enough for a 40T on their bike. All 10 speed XT derailleurs on Shimano's website are 780 series and all say max cog 36T.

    I'm going to assume mine is damaged and replace it with another M780 series, most likely a M786
    The Goat Link addresses that max cog limitation.

    You never responded to the question above about ensuring that the limit screws are totally backed out.

  12. #12
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    Quote Originally Posted by Harold View Post
    The Goat Link addresses that max cog limitation.

    You never responded to the question above about ensuring that the limit screws are totally backed out.
    Right....This is sort of baffling.

    Also, is the b-screw cranked enough so that the jockey wheel on the derailleur clears the biggest cog? Chain long enough?

  13. #13
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    Quote Originally Posted by Harold View Post
    The Goat Link addresses that max cog limitation.

    You never responded to the question above about ensuring that the limit screws are totally backed out.
    Quote Originally Posted by JACKL View Post
    Right....This is sort of baffling.

    Also, is the b-screw cranked enough so that the jockey wheel on the derailleur clears the biggest cog? Chain long enough?
    Yes, I have ensured the low limit screw is backed all the way out and the high limit is adjusted just to where it prevents the chain from moving past the 11T. The Goat Link certainly did allow for jockey wheel clearance of the 40T. I don't have a photo to show you at the moment, but I can clearly see the jockey wheel is a little off to the left of the 40T with the low limit screw backed all the way out when viewed from the rear of the bike.

    At this point I'm thinking the derailleur and/or drop out is bent or the rear triangle spacing makes the derailleur out of spec for a wide range cassette application. I'm considering making spacer to fit between the dropout and frame, but I need to rule out damage to the derailleur first.
    Thanks again for the input
    >>"Every chance I get!"

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