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Rear Di2 derailleur adjustment (R9100)
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So I finally was able to take my new Di2 setup outside now that winter is finally over up here (I'm in Canada) and I couldn't be happier on how smooth things work.

- BUT -

I noticed that when I'm in the big chain ring up front, there is some noise coming from the rear derailleur at the back (from mostly all cogs) but when i switch to the smaller chainring, its smooth as butter back there, and not a single peep from the RDR.

I've tried to adjust it before, but made a mess of it - mostly because I don't know what is causing it and what the action to fix it is. So I need to understand what is causing the noise, and how you go about and fix such issues.

Anyone willing to explain, i'd be forever grateful :)

3toronto Triathlon
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Re: Rear Di2 derailleur adjustment (R9100) [CBass@3toronto] [ In reply to ]
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Well, first thing I'd do is get it in the big ring and somewhere near the center of the cassette. Look at the chain underneath the cassette....is it centered between the cogs? If not, use the button on your junction box (hold down for 2 or 3 seconds) to put it into adjustment mode. If the chain was sitting closer to the larger/easier cog, use the shift button that you would normally use to shift to a harder gear, hit it a few times, it will micro adjust it the other way, or vice versa.. Then hold button down again to take it out of adjustment mode.

Hopefully just needs a small adjustment and won't throw off the small chainring tuning. Oh, also I guess make sure it isn't an issue with the chain being too short, top of derailleur cage hitting the gears, etc.
Last edited by: SBRcanuck: May 9, 18 9:12
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Re: Rear Di2 derailleur adjustment (R9100) [CBass@3toronto] [ In reply to ]
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RTFM ;)

Seriously, if you take a look at the Shimano Di2 manual for adjusting the rear derailleur and follow the instructions, you will get pretty close to smooth shifting. Basically you need to adjust the position of the chain in micro-steps to be in the center of the cogs.
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Re: Rear Di2 derailleur adjustment (R9100) [CBass@3toronto] [ In reply to ]
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Another potential culprit is the b-limit screw may need to be tightened down more. That will give more clearance between the upper pulley and the bottom of the cassette cogs.

Alex Arman

Strava
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Re: Rear Di2 derailleur adjustment (R9100) [CBass@3toronto] [ In reply to ]
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I'm gonna guess it's the b-tension adjustment screw that needs tweaking.

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Re: Rear Di2 derailleur adjustment (R9100) [JasoninHalifax] [ In reply to ]
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Just for my own learning, I like to understand what causes it and what it does.

mind expanding on why the B Screw might be causing the issue?

Btw - just to clarify - the shifting is smooth, no issues there. Its once the chain is on the cog, it makes a slight constant rattle.

3toronto Triathlon
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Re: Rear Di2 derailleur adjustment (R9100) [CBass@3toronto] [ In reply to ]
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the b-tension controls the preload on the spring at the pivot point where the rear derailleur attaches to the frame. not enough tension, and the upper jockey wheel will contact the cassette cogs. It will show up in the big ring rather than the small because in the small ring there is less tension on the spring in the other derailleur pivot point (where the cage attaches to the deralleur body), so the top spring isn't overwhelmed.

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2020 National Masters Champion - M50-54 - 50m Butterfly
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Re: Rear Di2 derailleur adjustment (R9100) [JasoninHalifax] [ In reply to ]
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Ah, gotcha - found a good video that shows this. Thanks!!

https://www.youtube.com/watch?v=QRhKaZd6GWQ

3toronto Triathlon
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Re: Rear Di2 derailleur adjustment (R9100) [CBass@3toronto] [ In reply to ]
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As others have suggested, either B-tension, or a short chain.

Shimano service instructions really are very good. :)

Developing aero, fit and other fun stuff at Red is Faster
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Re: Rear Di2 derailleur adjustment (R9100) [SkippyKitten] [ In reply to ]
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You think so? I feel like their manuals are very technical and for someone learning they miss explanation on details or key steps

3toronto Triathlon
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