Di2 front mech chain rub adjustment

5parky

My Di2 decided to mess up today, old of the blue while shifting, the front mech went out of alignment so I had chain rub from 6-11 using big ring. First thing I did was firmware update, changed the setting to 52/36 because for some reason it was on 53.

On then checking through the gears on the 52 only, all is almost fine without doing anything apart from chainrub on front mech in 52 in gear 11

I've had a look to see how to adjust the from mech but I'm not getting Shimano's wording. In the customise section of etube it says

'Set the front derailleur to the second speed and the rear derailleur to the first speed before
adjustment. Follow the instructions on the screen and then click [Set]

Would someone be able to clarify what this means please, do I need to do this before running etube too?

Thanks

wobblebob

'Set the front derailleur to the second speed and the rear derailleur to the first speed before
adjustment. Follow the instructions on the screen and then click [Set]' means put the front derailleur in the big ring and the rear on the biggest sprocket and then in adjustment mode you can microadjust the front derailleur

StillGoing

WobbleBob wrote:

'Set the front derailleur to the second speed and the rear derailleur to the first speed before
adjustment. Follow the instructions on the screen and then click [Set]' means put the front derailleur in the big ring and the rear on the biggest sprocket and then in adjustment mode you can microadjust the front derailleur

Reads the opposite to me. Big ring and 11 cog to set the outer limit and FD alignment. Then small ring and 28 (whatever biggest cog) to set the inner limit.

wobblebob

philthy3 wrote:

WobbleBob wrote:

'Set the front derailleur to the second speed and the rear derailleur to the first speed before
adjustment. Follow the instructions on the screen and then click [Set]' means put the front derailleur in the big ring and the rear on the biggest sprocket and then in adjustment mode you can microadjust the front derailleur

Reads the opposite to me. Big ring and 11 cog to set the outer limit and FD alignment. Then small ring and 28 (whatever biggest cog) to set the inner limit.

Inner and outer limits are still set with screws I think. It's been a while since I adjusted mine. I thought the question was about removing chain rub which would be a microadjustment.

Found this
https://di2center.com/2019/04/22/how-to ... your-bike/
Says 'Before you do anything, correctly set the high/low limit screws
Shift your rear derailleur to the largest cog (or lightest gear)
You may have to disable synchro–shifting to be able to do this.
Make sure the front derailleur is in the big ring (heaviest gear)
Press and hold the button on the junction box until the red LED illuminates to indicate you’re in adjustment mode (about 5 seconds)'

5parky

Just to make it clear, it's been fine for months so I doubt I need to adjust the limit screws. I just want to micro adjust the front mech because it's now got chainrub while on the 52 in 11...and I'm using etube (not the junction box)

5parky

My mistake, it seems that it's the 52 chainring teeth that's suddenly started catching on the front mech, not the chain. I tried adjusting the first adjustment when on 52/1 to -10 and it made no difference and left the setting when on the 36/1 as it was. I then decided to put the setting back down to 0 from -10

After completing the setup, it seems to be catching on the 52 for 10 and 11 now.

Maybe the shop can have it back since it's a recent upgrade

pilot_pete

If the chainring teeth are catching the mech then it simply isn’t set up correctly. It has to be either alignment or limit screw. How else can a chainring (not even the chain) catch on a front mech if the mech/ chainring are not damaged/ bent?

PP

5parky

Something moved during the ride so it's going back in the shop

pilot_pete

There’s no end float in the cranks is there? Can you push the cranks back and forwards through the BB? It would only take a few mm of endfloat not adjusted out and this could cause alignment changes between chainrings and FD.

Many cranks have wavey washers and/ or spacers to eliminate endfloat, my Rotor cranks have an adjuster ring which takes up any gap.

PP

5parky

Not that I could see, but the I did notice the front mech was not in line with the chainring so I've adjusted it and now it's not rubbing. It could probably do with some fine tuning because when on the 36, shifting to the 1 on the rear is a bit rough but I never use it and also there no 36 onto 10 or 11 which is a common issue...never use them either...then again it only causes chain strain.

pilot_pete

If I were you I’d download the (free) Shimano Dealer Manual for your particular model groupset. I’d take the chain off and set it up again from scratch ensuring you follow every step correctly. Your FD was not aligned correctly with the chainring. Is the height from the big chainring correct? Are the limit screws set accurately? Is the fine (electronic) adjustment done correctly? When all that is done correctly it will shift like a dream.

As for your rear shifting, it sounds like the B screw adjustment of the rear derailleur is not set correctly, or the indexing/ limits are not set correctly. Once again, follow the dealer manual guidance and set it all up accurately from scratch. Assuming nothing is damaged/ too worn, your shifting should become sublime.

PP

bongobiggins

5parky wrote:

Not that I could see, but the I did notice the front mech was not in line with the chainring so I've adjusted it and now it's not rubbing. It could probably do with some fine tuning because when on the 36, shifting to the 1 on the rear is a bit rough but I never use it and also there no 36 onto 10 or 11 which is a common issue...never use them either...then again it only causes chain strain.

If you are in semi syncro shift you won't be able to change into the bottom 2 if on the small front(unless you've changed the settings in e-tube). Take it out of syncro by double tapping the junction button(might have to do this more than once to get to normal shifting).

drexel1975

Moving out of synchro still won't allow you to use the smallest cogs when on the 36 chainring if you are using a 52-36 or 50-34. You have to manually tell etube that you are using another combination of chainring. Probably 53-39 will work. But it's not designed to be used going small-small with a compact or semi-compact chainring setup.