Di2 question: Shifters ST-R785 won't play nice with FD-R8050

[weisan]

When I connect the FD-R8050 directly using SM-PCE1, eTube recognizes the unit immediately and it passes the test check with no problem.

The problem arises when I connect the rest of the setup with shifters ST-R785 shifters, etube will only recognize the shifters but fail to recognize the FD-R8050.

One tell tale sign: if I connect the FD-8050 just using the charger SM-BCR2 and a junction box, it won't recognize either.

Off the computer, on the bike, the left shifter is not talking to the FD either, it won't shift.

Interestingly enough, when I connect that same FD to another bike that is running GRX di2, it shifts no problem. It begs the question: is ST-R785 incompatible with FD-R8050? Both are 11 speed.

What else could be the problem? Thanks for your help.


FD1 by Wei San Hui, on Flickr

FD4 by Wei San Hui, on Flickr

FD5 by Wei San Hui, on Flickr[/QUOTE]

[prototoast]

I have used those shifters with that derailleur. They're compatible. I suspect you have a problem with a cable.

[cmg]

When I replaced a rear derailleur I deleted it all and started from scratch. Consult a bike shop before doing that.

[weisan]

Originally Posted by prototoast

I have used those shifters with that derailleur. They're compatible. I suspect you have a problem with a cable.

Thanks for the confirmation proto pal, that's my understanding as well.

I have used that same cable to connect to a RD and it was recognized no problem, so I doubt that's the issue.

[weisan]

Originally Posted by cmg

When I replaced a rear derailleur I deleted it all and started from scratch. Consult a bike shop before doing that.

I have re-written the firmware multiple times, still the same. I think that's what you mean, correct?

[tonytourist]

What battery are you running? One of the older battery models wasn't compatible with some of the front derailleurs but I think it worked fine with the rear derailleurs. I remember my dad's 6870 FD died and when I swapped on 8050 front derailleur I had to change out the battery too. I happen to have a brand new Di2 battery here that I'm not using if you want a deal on a brand new one!

[weisan]

Originally Posted by tonytourist

What battery are you running? One of the older battery models wasn't compatible with some of the front derailleurs but I think it worked fine with the rear derailleurs. I remember my dad's 6870 FD died and when I swapped on 8050 front derailleur I had to change out the battery too. I happen to have a brand new Di2 battery here that I'm not using if you want a deal on a brand new one!

I have tested the battery with two different RDs, and they both worked and responded wonderfully to the shifters so I think the battery is good.

Thanks for your kind offer, I actually have a need for another battery so I might hit you up on it in a PM. Thank you!

[weisan]

Originally Posted by prototoast

I have used those shifters with that derailleur. They're compatible. I suspect you have a problem with a cable.

Proto pal, I should have listened to you earlier. I went back and tested with a different cable and this time, everything worked!!

Thank you so much for your help. You are a trusted source around here.