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Di2 setup problems
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I’ve been running Di2 for a couple of years with no problems. I’ve just moved it across to a new frame and I can’t figure out what is going on. I’ve tried the manual and google To no avail. Hopefully someone here can help. I set it up with e-tube and every gear works fine apart from 5,6 and 7 (going largest sprocket to smallest) on the rear when combined with the small ring at the front. In 5 the chain starts to rub on the derailleur (the underside of the chain) and by 7 The chain is slack and ‘hanging’ on the front derailleur. When using the large chainring all the gears are good. I think the chain is the correct length. I have a wedge spacer on the front derailleur to angle it down a little. This is driving me nuts! I have some pics but I need to shrink them before uploading. Please help. Thanks
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Re: Di2 setup problems [east31] [ In reply to ]
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Without pictures or a video, I couldn’t quite tell what exactly you are describing. The whole 5/6/7 thing is confusing.
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Re: Di2 setup problems [east31] [ In reply to ]
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It’s the same reference that Shimano use in their manuals. So 1 is the largest cog on the cassette, 11 is the smallest. Number 5 is what Shimano suggests using for tuning the rear derailleur. So as I shift to a higher gear I have no problems with 1-4, problems with 5-7 and then Synchro shifts to the big front ring. I have no problems with any gear while in the big ring. I hope that makes more sense



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Re: Di2 setup problems [east31] [ In reply to ]
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Chain too long on the new frame? (likely the chain stays are shorter on the new frame?)

http://www.machinehead-software.co.uk/...chainlengthcalc.html
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Re: Di2 setup problems [east31] [ In reply to ]
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Download the full shop manual on di2 to understand how to do this. If you follow ALL those steps it’s foolproof. If chain length is correct (assumption) then you have an improperly adjusted b-tension bolt. The rest is di2 setup and easier to read from the manual.

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Re: Di2 setup problems [east31] [ In reply to ]
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Chain looks too long to me. What does it look like in the big big combo? If the cage isn't pointing toward the cranks like in pic below (bottom right) then it's way too long.




Search for chain sizing techniques. Or check out the one one the main site here: https://www.slowtwitch.com/...o_-_Part_1_3279.html

Like another already posted different bikes have different chainstay lengths. So what work for chain length on one bike wouldn't necessarily be the same for a different brand or model even if they are both close in fit geometry.
Last edited by: loxx0050: Jul 31, 20 20:03
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Re: Di2 setup problems [east31] [ In reply to ]
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east31 wrote:
It’s the same reference that Shimano use in their manuals. So 1 is the largest cog on the cassette, 11 is the smallest. Number 5 is what Shimano suggests using for tuning the rear derailleur. So as I shift to a higher gear I have no problems with 1-4, problems with 5-7 and then Synchro shifts to the big front ring. I have no problems with any gear while in the big ring. I hope that makes more sense


Ummm... your chain is too long.
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Re: Di2 setup problems [east31] [ In reply to ]
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east31 wrote:
I’ve been running Di2 for a couple of years with no problems. I’ve just moved it across to a new frame and I can’t figure out what is going on. I’ve tried the manual and google To no avail. Hopefully someone here can help. I set it up with e-tube and every gear works fine apart from 5,6 and 7 (going largest sprocket to smallest) on the rear when combined with the small ring at the front. In 5 the chain starts to rub on the derailleur (the underside of the chain) and by 7 The chain is slack and ‘hanging’ on the front derailleur. When using the large chainring all the gears are good. I think the chain is the correct length. I have a wedge spacer on the front derailleur to angle it down a little. This is driving me nuts! I have some pics but I need to shrink them before uploading. Please help. Thanks
From the angle of the derailleur, it looks like you have trapped the B tension atab when you fit the derailleur and hence now have no B tension.
Remove derailleur, straighten the hanger which you have now probably bent, refit derailleur taking care to fit B tension tab correctly, finish setup as per usual.
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Re: Di2 setup problems [east31] [ In reply to ]
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Thanks for all the help. Problem solved. So I had read the manual cover to cover before posting. I had shortened the chain using the big ring/big sprocket and 2 links method but I took a link to mean a wide plus a narrow section rather than just 1 section (a link duh!) I double checked the chain length using the Slowtwitch method (great article - thanks for the link) and then shortened the chain but I still and some fd derailleur rub. Using e-tube I realised that in resetting the settings the chain rings had resorted to a 53/39. I switched to 52/36, ran the setup again and all seems good! Thanks so much for your input!

While we are here I understand synchro and semi synchro but I would assume that manual would give me separate control of the rd using the extension switches and fd using the base bar switches. I don’t have that. Should I? I’m wondering if I messed up a setting when I first got it. Thanks
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Re: Di2 setup problems [east31] [ In reply to ]
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You can change the functionality of each button, but you cannot change it per shift mode. If you set a button to switch the RD only then that button will always shift the RD only - no matter what shift mode you're in.

Maybe they'll change this at some point in the future... would be nice ;)

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Re: Di2 setup problems [Di2Terry] [ In reply to ]
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Thanks for clarifying. I thought that I had screwed up one of the modes. Nice to know that’s just the way it is.
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Re: Di2 setup problems [east31] [ In reply to ]
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The new generation of rear derailleurs set up differently from everything that came before it.

A properly sized chain could appear to be too long (and sag) if the end bolt (The B-tension screw) is not properly set. If you tighten (screw in) the end bolt, you'll see that the chain slack will quickly be taken up.

Look here on page 129 for instructions and images
https://si.shimano.com/.../DM-R8050-01-ENG.pdf
"If there is any slack in the chain when the chain is mounted on the smallest chainring and smallest sprocket, adjust the end adjust bolt to eliminate it."
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