Di2 6870 front derailleur doesn't stay still - Advice needed

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vtspot
Posts: 48
Joined: Mon Jun 02, 2014 4:34 am

by vtspot

Greetings,
To cut a story short, My bike has a problem to change from small to big chainring.
When my bike is on the cycle stand, the shifting works 100% fine.

However, when I test my bike on the road, changing from small to big chainring doesn't work intermittently.
When it does not change successfully, the chain just drops.

I have followed the instructions from shimano manual, including making sure the out plate is parallel, leaving 1-3mm space between fd and chainrings, playing with the Low & High setting and other adjustment that can be found in the manual.

There is one thing I realized is that my Di2 6870 front derailleur does't stay still when changing from small to big chainring.
To better explain the scenario, i found an video from youtube. Here is the video link:
http://www.youtube.com/watch?v=i2ddHddKlK0
You can see how the FD move a bit when changing from small to big. The force to change from small to big ring causing the FD not able to stay still.

I have made sure that the braze on tab is stiff and is screwed tightly and securely on the frame, and FD is attached firmly on the braze on tab.
However, the FD is still moving when changing small to big chainring.

Is the "moving" part normal?
Is it possible that this is the cause of the problem of switching from small to big chainring, that I explained at the beginning?

Your advice is much appreciated.

by Weenie


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Gearhead65
Posts: 110
Joined: Sat Jan 23, 2010 1:24 am
Location: Evansville, IN, USA

by Gearhead65

I'm going to guess that the Support Bolt (C), Page 22. that anchors the FD against the hanger is not screwed in and adjusted.
2015 Specialized Crux Pro
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rmerka
Posts: 618
Joined: Wed Mar 06, 2013 4:23 pm
Location: Austin, TX

by rmerka

99.9999% sure Gearhead65 is right. I always set a Di2 system up with cage angled in and then use the support bolt to make it parallel. Always works.

mike
Resident Pro
Posts: 2983
Joined: Tue Mar 18, 2003 9:42 pm

by mike

same as above. loose screw. this is common especially on campy eps front derailleurs if you don't torqure that square bolt tight enough. it works itself loose.

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