DI2 setup small ring rubbing front derailleur cage

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muntos
Posts: 247
Joined: Wed May 29, 2013 5:41 pm
Location: Romania

by muntos

So I have setup my Scott Foil with DI2 (Ultegra 6870) and no matter how much I tried I can't make it to work fine with small chainring (36T Rotor Q-ring) in combination with the last smallet 4 cogs (11-28 cassette). The chain is rubbing the outside part of the front derailleur cage, not very hard but still I can hear it...
I properly set the HI and LO limits, if I push more the HI limit then the chain is dropped outside of the big ring when switching from the small one...
I've read that on some frame geometries (with short chainstay) the chain will always rub on the last 2 cogs but 4 as in my situation seems too much for me.
There is a trim function in e-Tube project but it doesn't seem to make the difference, maybe I'm doing something wrong or not doing something ?
Does anyone stumbled on this problem and managed to find a solution?
For me it seems to be quite a little stupid for a electronic transmission to not be able to solve these combinations, in the end the front derailleur trim function could work on every rear change to put the cage in the middle of the chain (maybe it doesn't do it to save battery...?)

beanbiken
Posts: 828
Joined: Tue Mar 18, 2014 10:13 pm
Location: Great Southern Land

by beanbiken

With the front derailleur there are 3 adjustments (DA9070) hi, low and then the electrical trimming. Some basics as with the rear but put in in trim mode an use the front derailleur paddles to trim it. I have 9070 on a Pinarello F8 with zero rubbing
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by Weenie


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muntos
Posts: 247
Joined: Wed May 29, 2013 5:41 pm
Location: Romania

by muntos

To put it in trim mode I need to keep pressed the button on junction A until a red led lights up, right ? I've tried this and pressed the front derailleur pads but nothing seems to happen, I only successfully able to move the derailleur using the + and - trim functions in e-tube project ?
Or also I need to move the front derailleur on big ring and the rear on biggest cog in order to use the trim function with the paddles...?


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mai
Posts: 50
Joined: Sun Feb 14, 2016 10:05 am
Location: Hong Kong

by mai

yes - fd trim adjustable only when in big ring/big cog

Zigmeister
Posts: 938
Joined: Mon Jan 24, 2011 8:09 pm

by Zigmeister

Yes, as above, trim only works on the FD in big ring. Good video link as well.

You start the setup process just like a mechanical group, by using the set screws. Then, work with "trimming" electronically after that.

Once that is done, then you can run through the gears, and trim on the big ring if a problem. Also, you can use the set screw while in the big ring as well, Hi/Lo. Once that is done, you should have not worries due to auto trimming of the FD as you move through the gears.

I've only had to make 1 tweak with the set screw in 2 years after changing to a different rear cassette, new chainrings and chain....so once it is setup, it should just work.

Of course, electronic shifting doesn't solve massive cross chaining issues...just don't do that. Not sure why people do that...but whatever.

by Weenie


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