Road Bike, Cycling Forums banner
1 - 2 of 2 Posts

·
Registered
Joined
·
427 Posts
I concur with CX. This sounds like a problem with the setup of the FD. The computer settings are not needed to make the FD shift and auto-trim properly.

A few things I've noted in installing a few of these (I'm no pro).

1. You need to follow Shimano's instructions carefully for how you align the FD cage PRIOR to tightening the support bolt. You want the back of the cage somewhat INWARD from the front at first. Then, when you tighten the support bolt you want it to bring the outside of the cage directly over the big ring AND direclty parallel. Tightening the bolt moves the cage out, but it also twists the cage by pushing the back of it out faster.

2. Assuming you get the above right, then just make sure your low and high limits are set.

3. After that, you do have a way to micro-adjust the FD precisely so as to remove chain rub in the auto-trim feature. You activate it by first shifting into the big-big combo, and then holding down the button on junction A. The buttons set to move the FD will then microadjust so that you can eliminate any chain rub.

My actual hunch is that your problem is the support bolt and alignment, since usually microadjustments aren't necessary. As cx says, if you put the FD in the proper spot, it will auto-trim fine.
 

·
Registered
Joined
·
427 Posts
Never heard of a Di2 microadjust on the front DR, only the back. After alignment and height are adjusted you just set the Low limit (while in the little ring front, big cog back) and the high limit (big ring front and little cog back).
Often there is no NEED to do the FD micro-adjust, bit it IS a part of the system. It's detailed in the Shimano manual and if you have an A junction with a display (SC-MT800) it even shows you when you are in the Front micro adjust mode.

As as I said above, you enter the FD micro-adjust mode by shifting to big big and then holding down the junction A button. After that, the FD shift buttons will move the FD by tiny amounts either inboard or outboard.
 
1 - 2 of 2 Posts
Top