Gear Control on 6870 Di2?
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  1. #1
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    Gear Control on 6870 Di2?

    I would like to have the Di2 prevent going to small small on my 6870 system so I can use a 11/36 cassette with a GS cage and not worry about the chain getting too loose. I can't find anyway to do this on the system in E-Tube, but have read it's part of the system for 8050 (Gear Control) when the rings are identified as 50/34 or 52/36. If it's not possible on 6870, would putting a 8050 GS Rear on with the rest of the system being 6870 enable it? (I have the latest battery and firmware)
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  2. #2
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    I would stick with what you have and just avoid small/small. Pretty easy to do.

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    Possible I would not forget but on a long ride over 12 hours I have coming up with lots of shifting I'll probably screw that up - would rather not have to worry about it if I can make it work spending a couple hundred on an 8050 RDR
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  4. #4
    tlg
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    What do you mean by your chain getting too loose? If sized right, your chain shouldn't be loose.
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  5. #5
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    Quote Originally Posted by tlg View Post
    What do you mean by your chain getting too loose? If sized right, your chain shouldn't be loose.
    an 11/36 cassette is 4 teeth over the capacity of a long cage 6870 rear per the specs. I have an 11/34 on it now, but it's pushing the limit, the dr is almost horizontal in the 11/34, and its pulling really close to the 34 cog touching the rdr gear with the B screw all the way in in the big ring, need to add a link to get the 36 to work. Adding a link is going to leave a slack situation small / small
    Last edited by Srode; 2 Weeks Ago at 12:46 PM.
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  6. #6
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    Quote Originally Posted by Srode View Post
    an 11/36 cassette is 4 teeth over the capacity of a long cage 6870 rear per the specs. I have an 11/34 on it now, but it's pushing the limit, the dr is almost horizontal in the 11/34, and its pulling really close to the 34 cog touching the rdr gear with the B screw all the way in in the big ring, need to add a link to get the 36 to work. Adding a link is going to leave a slack situation small / small
    Having the chain hang slack in the rare poor small-small gear choice is not a problem. And most likely you will get an audio warning as the chain rubs on the big ring. You will then shift out of that gear choice. Problem solved.

  7. #7
    'brifter' is a lame word.
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    Quote Originally Posted by Srode View Post
    Possible I would not forget but on a long ride over 12 hours I have coming up with lots of shifting I'll probably screw that up - would rather not have to worry about it if I can make it work spending a couple hundred on an 8050 RDR
    Seriously?
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    Quote Originally Posted by cxwrench View Post
    Seriously?
    Maybe he won the RAMROD Lottery?

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    I've never done this, but it's typically a 10 hour ride for most people (some much faster, some slower)

  9. #9
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    I'm running my di2 beyond specification. My chain is 'loose' in the small-small, only a problem if the road is very bumpy. I had the chain tighter, but it locked up in the big-big, as it is hard to remember where you are on the cogs/ring when your riding with O'Riordan.
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    Quote Originally Posted by duriel View Post
    My chain is 'loose' in the small-small, only a problem if the road is very bumpy.
    Well, its on a gravel bike so lots of very bumpy roads which is exactly my concern. I have an 8050 rear coming tomorrow so I'll find out how it works in E-tube with that, shouldn't be any worse than my current 11/34 when I switch to 11/36 it seems, plus I might be able to lock out the small small.
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  11. #11
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    Quote Originally Posted by cxwrench View Post
    Seriously?
    Dirty Kanza 200 - I haven't been done before 10:30pm on it yet, maybe this year. The price of age is being slow.
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  12. #12
    'brifter' is a lame word.
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    Quote Originally Posted by Srode View Post
    Dirty Kanza 200 - I haven't been done before 10:30pm on it yet, maybe this year. The price of age is being slow.
    That's about 180mi longer than I'm good for
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    Quote Originally Posted by cxwrench View Post
    That's about 180mi longer than I'm good for
    Well I'm not "good" for that long, but I survive it!

    Plugged in the 8050 without mounting it and gear control showed up on Etube. I tried to fake it out by closing Etube with it plugged in, the plugging the 6870 but that didn't work, apparently that setting doesn't stick in the battery memory if you switch parts. I'll swap it out and cut a new chain sized for the new cassette next week.
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  14. #14
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    Maybe go to the hardware store and buy a longer b screw?

  15. #15
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    Quote Originally Posted by seppo17 View Post
    Maybe go to the hardware store and buy a longer b screw?
    No, that is not a fix. Do not do this.
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  16. #16
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    So, Shimano uses the same pulley cages for 6800/6970 derailleures. Ever thought about swapping to long cage on the existing derailleur?

  17. #17
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    Quote Originally Posted by 202cycle View Post
    So, Shimano uses the same pulley cages for 6800/6970 derailleures. Ever thought about swapping to long cage on the existing derailleur?
    Well, it is the GS (long) cage on the bike - that's what is really too short. The 8050 long cage will do the trick and lock out the small small, problem solved, just need to mount it and throw on a new chain.
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  18. #18
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    Quote Originally Posted by Srode View Post
    Well, it is the GS (long) cage on the bike - that's what is really too short. The 8050 long cage will do the trick and lock out the small small, problem solved, just need to mount it and throw on a new chain.
    Isn’t the 8050 GS derailer their “long cage” derailer ?? As opposed to SS ?

  19. #19
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    yes, the 8050 GS is the long cage, and i had the 6870 long cage also GS (should have been more clear it was the 6870 GS rear). I picked up an 8050 GS to replace the 6870 GS because the shimano "Gear Control" works with the 8050 cage, and not the 6870 (doesn't even show up in etube with a 6870 GS rear dr plugged in) and I want the gear control.
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