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    Shimano grx won’t get in the big cog

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    16 Comments

    2. IndyWheelLab on

      Have you tried increasing cable tension by rotating the barrel adjuster counterclockwise by 1/4 turn increments?

    4. iJustRedd1t on

      Low limit screw meaning if that’s the max it will go to, then you have a bad dearilire, or hanger. Maybe apply more tension to the cable and see if it had the ability to go that far

    5. alphabetizedsoup on

      Everyone here is suggesting limit screws, but I’d also try a new cable OP. Yours looks pretty frayed and that might be causing too much friction in the housing assuming your limit screws are good.

    6. Ok-Till2619 on

      Which grz derailleur and what ratio cassette? Is it bigger than suggested as it looks huge?

    7. SnollyG on

      If you’re not able to push it further by hand (don’t shift), then it’s your L limit setting a hard stop on how far over it can go.

      If you can push the derailleur over more, then it’s a cable tension issue.

      If the upper jockey wheel is hitting the big cog, then it’s not enough B tension adjustment.

      If none of those, then your hanger may be bent.

    8. kalisto16 on

      Honestly, you should read the Shinano tech docs. They are free online and i feel like they are an under utilized resource.

      The B tension screw will do something, it will move the pully closer/further away from your largest cog. it looks too close, but can’t really tell. Leave it in the largest cog and turn it, if nothing happens you’re likely turning the wrong thing.

      Your upper limit might also be off, back that off a bit maybe?

      You should be able to see where the limit screws and b tension screw come in contact with the derailleur and how turning them impacts the setup.

      Edit: Also you should install your chain, it will pull your lower pulley forward and change the distance between your largest cog and upper pulley wheel.

    9. singelingtracks on

      First Step remove the cable from the rear deralliuer

      Then move the deralliuer fully by hand.

      If it won’t go into the biggest gear, then adjust your limit screw, check it also does the smallest.

      That’s it. There’s nothing magical with rear derallieurs.

      Reattach your cable and flick through the gears if you have issues adjust the cable tension.
      If it won’t go into a gear then either your cable isnt smooth or your shifter has failed.

      Once everything is lined up adjust your b tension screw for the proper gap on your largest rear ring.

    10. millenialismistical on

      If the L limit is set correctly (which is hard to tell from the video but it doesn’t look like it is), then you might increase the cable tension a bit to see if that helps it get there. B screw and chain length (too short) are other things I would look at if L limit and cable tension adjustments do not resolve.

    11. Daedaluu5 on

      Needs a wolf tooth to offset it. Even with a 10cog 10mech if the big ring is too big it doesn’t move out enough. If it’s gravel mech it’s trying to give mtb range and cog sizes on a roadie setup.

    12. nalonso on

      Look for Park tool video on rear derailleur adjustment. I just watched it this morning before adjusting mine.

    14. samsonsu on

      If you are sure your limit screws and b screws are properly adjusted, and your derailleur is not damaged, it could be the cable tension. It got loose (normal for new bikes after some break in time) and the big cog requires a lot of tension to get to. You could use that tension barrel adjuster by turning it counter clockwise little by little, which adds tension to the cable. But that might not give you sufficient range to fix your problem. A more proper, long term way is to shift to smallest cog, loosen the cable pinch screw, and re-tighten it while pulling the cable snug (but not too tight). Before tightening the pinch screw, turn the barrel adjuster clockwise to the end then back out a few rounds, so that it gives you some range of micro adjustments in both directions.

      For my SRAM 12x i had to do this after first few hundred miles on my new bike. Then it worked flawlessly for thousands of miles after. I guess new cable has some room for stretching but it stabilizes after some age.

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