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  1. #1
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    11-34 with GS 6800 rear DR and compact Crank?

    Anyone using the Shimano 11-34 cassette with a GS 6800 rear DR and compact crank? Looking at my gravel bike, it has an 11-32 on it now and the B screw is cranked pretty much all the way in - looks like it might work with one more set of links in the chain and still keep a little tension on the cage when going small small. I'm guessing its going to depend on the frame (Niner RLT9) and hanger really, but thought I would check and see how many if anyone is running that set up here now.
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  2. #2
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    Have that exact set up on my wife's bike and shifts perfect

  3. #3
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    Interesting, I've got an RLT9 and I was able to clear a 36 in back with no issues and the B-tension screw still had 1/4 of the way to go. It's a 1st gen frame though so maybe they tightened things up in the next revision. Worked fine with a 6800, even better with the newer 8000. Probably heading towards the new shadow+ design once it's available.

  4. #4
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    There are two issues with using a rear derailleur that is out of spec with your drivetrain.

    1) Chain wrap capacity of the cage
    2) Derailleur geometry

    The first issue is the most important and ensures that you will have some tension in the small/small combo while still being able to shift to the large/large combo without binding. Binding is bad, mmmkay?

    The second issue can be dealt with more easily. If the rear derailleur is used with a cog larger than what it is designed for, you may not be able to adjust the b-screw in far enough without the dreaded "motor boating" noise which is the sound of the jockey pulley against the cog. While this is annoying and can wear out your drivetrain faster, it will not result in any catastrophic failure.

    The Wolf Tooth Road Link can solve the second issue, but not the first.

    The Shimano GS-6800 rear derailleur (mid-cage) is designed to work with up to a 32T cog. The new GS-R8000 is designed to work with up to a 34T cog.

    Some people have found they can push that up to 2 more teeth without problems.
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  5. #5
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    Quote Originally Posted by rcb78 View Post
    Interesting, I've got an RLT9 and I was able to clear a 36 in back with no issues and the B-tension screw still had 1/4 of the way to go. It's a 1st gen frame though so maybe they tightened things up in the next revision. Worked fine with a 6800, even better with the newer 8000. Probably heading towards the new shadow+ design once it's available.
    Mine's a 1st gen frame too so guess it should work fine. I'll relook at the B Tension screw, maybe I have more room on it to play with than I think. Thanks!
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  6. #6
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    Quote Originally Posted by Srode View Post
    Mine's a 1st gen frame too so guess it should work fine. I'll relook at the B Tension screw, maybe I have more room on it to play with than I think. Thanks!
    Be careful cranking in the b-tension screw a bunch, as you do that you're reducing the number of teeth the chain wraps. It's only a couple, but if you have wear issues you might notice the chain skipping a little sooner. It will also have a small affect on shifting in the smaller cogs as the pulley will be further away from the cog.
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  7. #7
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    Quote Originally Posted by cxwrench View Post
    Be careful cranking in the b-tension screw a bunch, as you do that you're reducing the number of teeth the chain wraps. It's only a couple, but if you have wear issues you might notice the chain skipping a little sooner. It will also have a small affect on shifting in the smaller cogs as the pulley will be further away from the cog.
    Thanks, very helpful. I'll keep it as close as possible to the big cog and see how well it works. Right now I think the the 32 it has a fair gap and seems to shift well across the cassette.
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  8. #8
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    Knowing your setup, I'm fairly confident you'll be fine with the 34. If you're thinking 36, then I'd jump up to the rd-8000. Like I said the 6800 worked, but the 8000 works better.

  9. #9
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    Quote Originally Posted by rcb78 View Post
    Knowing your setup, I'm fairly confident you'll be fine with the 34. If you're thinking 36, then I'd jump up to the rd-8000. Like I said the 6800 worked, but the 8000 works better.
    Mine is the 6800 series Di2, not sure the 8000 is going to be compatible with that - it has the older style battery. Playing with it last night it looks like I won't have to make any adjustments on the B screw or chain length for it to work. I just ordered the cassette, should be here Friday so I'll see how it works this weekend. Thanks!
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  10. #10
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    Quote Originally Posted by Srode View Post
    Mine is the 6800 series Di2, not sure the 8000 is going to be compatible with that - it has the older style battery. Playing with it last night it looks like I won't have to make any adjustments on the B screw or chain length for it to work. I just ordered the cassette, should be here Friday so I'll see how it works this weekend. Thanks!
    I just installed 8070 derailleurs on a bike w/ an old battery and they worked fine, including blocking the 3 small cogs when in the small chainring...not sure how it knew, but that's how it worked.
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  11. #11
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    I have been 'told' that you should be able to mix and match 6800 and 8000 just fine. But then again they also said you could make 10sp into 11sp with an RD swap (+chain/cassette) and leave the FD and STIs, but then changed their minds a few months later and bricked a bunch of setups, so who knows with Shimano.?.?

  12. #12
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    Quote Originally Posted by rcb78 View Post
    I have been 'told' that you should be able to mix and match 6800 and 8000 just fine. But then again they also said you could make 10sp into 11sp with an RD swap (+chain/cassette) and leave the FD and STIs, but then changed their minds a few months later and bricked a bunch of setups, so who knows with Shimano.?.?
    The bike I posted about is 10 speed. Had to install both 8070 derailleurs but it works perfectly w/ 10 speed shifters. As I remember it's a 36 as well.

    Last edited by cxwrench; 4 Weeks Ago at 01:25 PM.
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  13. #13
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    Quote Originally Posted by cxwrench View Post
    The bike I posted about is 10 speed. Had to install both 8070 derailleurs but it works perfectly w/ 10 speed shifters.
    Huh? How is this possible? Aren't 8000 series derailleurs designed to work with 11-speed groups? Aren't 10 and 11 speed groups a different pull ratio?
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  14. #14
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    Quote Originally Posted by cxwrench View Post
    I just installed 8070 derailleurs on a bike w/ an old battery and they worked fine, including blocking the 3 small cogs when in the small chainring...not sure how it knew, but that's how it worked.
    Can you disable the blocking? Being forced to shift between chain rings more often on a gravel bike doesn't sound attractive.
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  15. #15
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    Quote Originally Posted by Srode View Post
    Can you disable the blocking? Being forced to shift between chain rings more often on a gravel bike doesn't sound attractive.
    Certain crank/cassette combinations have a toggle-able setting to turn-off the nanny-ism. Others don't.


    Shimano has taken after iPhone...they let you do things and not others--and god knows why or why not.
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  16. #16
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    Quote Originally Posted by Marc View Post
    Certain crank/cassette combinations have a toggle-able setting to turn-off the nanny-ism. Others don't.


    Shimano has taken after iPhone...they let you do things and not others--and god knows why or why not.
    Another reason I have no interest in going to e-shifting.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

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  17. #17
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    Quote Originally Posted by cxwrench View Post
    The bike I posted about is 10 speed. Had to install both 8070 derailleurs but it works perfectly w/ 10 speed shifters. As I remember it's a 36 as well.
    Good to know, I'll have to remember that.

    Quote Originally Posted by Lombard View Post
    Huh? How is this possible? Aren't 8000 series derailleurs designed to work with 11-speed groups? Aren't 10 and 11 speed groups a different pull ratio?
    Originally the story was that the shift indexing is completely held within the firmware for RD for DI2. The shifters are just switches and the front doesn't care too much about the back, except for the trim could be off a hair. So you could take a DI2 10sp group, swap the chain, cassette and RD and voila, 11sp. Then Shimano changed their mind and made a firmware change that forced you to match speeds of all components. I 'thought' that included shifters, but based on CX's post that seem to not be the case which is good news for people looking to upgrade to 11sp and keep costs down.
    The addition of the 11-34 cassette makes it even more cost effective as it will fit a 10sp FH body the same way an MTB 11sp cassette does by hanging the 34t cog over the wheel dish. This will let people with wheels that can't be fit with 11sp FH bodies, to still run an 11sp road group, they will just have to live with only one cassette choice.

  18. #18
    Adorable Furry Hombre
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    Quote Originally Posted by Lombard View Post
    Another reason I have no interest in going to e-shifting.

    Shifting (down) while braking, multiple shifting...shifting speed, minimal lever throw needed to shift. Stuff is great. You just lie to e-tube or don't tell it.
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  19. #19
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    Quote Originally Posted by Marc View Post
    Shifting (down) while braking, multiple shifting...shifting speed, minimal lever throw needed to shift. Stuff is great. You just lie to e-tube or don't tell it.
    Or etap.
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  20. #20
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    Quote Originally Posted by Marc View Post
    Shifting (down) while braking, multiple shifting...shifting speed, minimal lever throw needed to shift. Stuff is great. You just lie to e-tube or don't tell it.
    Cool, I can tell it a white lie!
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  21. #21
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    Looks good to me, shifts fine hanging on the wall into the big big - will road test it this weekend but not anticipating any problems. Thanks for the help guys!

    11-34 with GS 6800 rear DR and compact Crank?-11-34.jpg
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  22. #22
    'brifter' is a lame word.
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    That looks like it should work fine.
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