TimothyH

Not really interested in opinions of Di2 so start your own thread if that's your comment.

This thread is about an FD-R8050 which had been working fine and the cage is suddenly too far outboard. It won't shift into the little ring and drops the chain on the outside of the big ring.

Nothing changed. No work was done to the bike. It was transported on its side, drive side up in the back of an SUV and was ridden about a mile or two before a race Saturday. Nothing was wrong at that time. I noticed something wrong as soon as the race started and it had to be run as a 1x in the big ring all day.

The high screw is turned all the way out so the derailleur cage is as far inboard as possible The brace screw is correctly tightened. I've put it in adjustment mode and moved the derailleur all the way inboard 24 clicks. It is still too far outboard.

Crankset was removed and the bottom bracket was checked - it is tight and no bearing issues. I can't see any cracks in the frame. The derailleur clamp was removed, cleaned and reinstalled with no issues found. The derailleur cage is parallel with the chainrings so it isn't an angle/clamp rotation issue. Nothing on the derailleur appears bent.

Neither PC nor iPhone versions of E-Tube have the error check function but I did hook up the system both ways and updates firmware on the FD, RD, wireless unit and battery. No change.

The cage is just too far outboard.

I'm about to initiate a warranty claim but am supposed to go bikepacking Sunday and would like to resolve this if possible. This will be the third time I've postponed this trip and I'd hate to have to wait. Hopefully someone has heard of this issue and can advise.


-Tim-

jadocs

That’s super strange. So you still have the normal range of adjustment and it still shifts but is too far outboard?

Cyclist0108

OK, if it was working fine before, and nothing has changed (or has broken), it should be possible to re-zero it and start afresh. (You have nothing to lose).

If nothing else, get the chain on the smaller chainring so you can do your trip.

Slightly coincidently, I had to adjust my H limit screw for the first time in 5 years. I have no idea why.

At risk of telling you what you already know:

Cyclist0108

The only other thing I can think of is Crash Recovery Mode, but I think this is only something that would involve the rear derailleur.

ChinookTx

Is it setup braze or clamp on? Is it possible the clamp moved, or the braze got bent?

Edit: Nevermind, I read the post properly.

Cyclist0108

Is this the small one next to the low-limit screw that adjusts yaw? Mine (an older version) is a clamp-on, and doesn't appear to have this screw. Are you SURE you haven't been messing with the low-limit screw?

Marcus_Ti

There are only 18 adjustment stops on the FD in each direction from the starting (0) position....at least according to pg137 of the Shimano DM.

Are your chainring bolts still secured?


Is yours a braze-on or a clamp on? You mentioned the frame looks good--is the braze (if applicable) still healthy and hearty? When you put things back together were the spacers/washers correctly distributed DS/NDS? Needing more than the programmed Di2 stop adjustments to me shouts out-of-spec RD mounting...and the only way that overnight happens is something breaking....

Cyclist0108

He says it is a clamp-on. Hence my question.


Another idea:

Did you take apart the crank or bb, and if so, is there any chance a spacer got put in differently?

TimothyH

Yes, exactly.


How? Is there a factory default reset procedure or something?

Or do you mean setting it up from scratch?


This is an R8050, not a 6870. The R8050 does not have a low limit screw.

The small screw is a "support bolt" which touches the seat tube or derailleur clamp and prevents the derailleur from flexing as it shunts the chain on upshifts.


The number of adjustment stops is interesting. The manual says there are 37 total (18 inboard and 18 outboard from center). Mine only moves 24 steps total. I might look at it again tonight just to be sure.

It is a braze-on derailleur with the braze-on clamp adapter on the seat tube. The chainring bolts are tight. Cranks are Ultegra with Enduro Torqtite bottom bracket set up the same way they have always been.

It didn't break overnight. I rode it 1 or 2 miles warmup before the race and it was fine. I sat 20 minutes at the start line, the gun went off, I started to pedal and knew something was wrong right away due to chain rub. The first downshift failed to move into the small ring and subsequent upshift moved the chain off the big ring on the outside. Something changed between warm up and starting the race.


-Tim-

ChinookTx

Have you checked that there's no broken part? I seem to recall a thread about a broken "lever" on the FD. Something like:

wsteve464

Since the Di2 is an electrical system the FD gets a signal from the shifter then the charging thing in the handle bars. For the problem to have happened so quickly it sounds like an electrical failure more than a mechanical one.

Do you have another Di2 bike or buddy with one to swap parts to trouble shoot? I would start with the handle bar charger unit.

You can buy a climbing switch to replace the brake lever/shifter switch to eliminate that part.

Good luck

TimothyH

What's wrong with it is now moot. The mounting bolt hole is now stripped. The threads have pulled out and the derailleur can no longer be mounted. I'm scrupulous about using a torque wrench but there it is.

A few more data points for posterity...

It does move 36 increments when Di2 is placed into front derailleur adjustment mode.

The derailleur was placed into adjustment mode and moved all the way inboard, 36 clicks. The high limit screw was completely removed. This placed the derailleur cage as far inboard as it can possibly go but even so, the outer cage plate was still outboard of the big ring. This convinces me that something inside the derailleur bent, gears have skipped or similar.

Either way, it is fubar.

Three attempts to get this bikepacking trip done...

wsteve464

Get a helicoil insert installed

surak

Strange coincidence that my Di2 FD also suddenly went too far outboard and I had the chain drop off the big ring this past Saturday in the middle of a ride. My LBS said the bolts were loose and the support bolt wasn't even touching the frame. My FD is also a braze on setup. I never did anything to the FD other than playing with the micro adjustment setting when I first got the bike back in April, and the shop built it up for my test ride of it so I assume everything should have been torqued to spec.

TimothyH

Bolts were loose?

Which bolts?


-Tim-

surak

I didn't inquire deeply but I think the issue was the fixing bolt.

TimothyH

OK, yeah, that'll do it.


-Tim-