Originally Posted by
mtseymour
If you want prefer a mechanical front derailleur (for triple road crank), it's better to go with Ultegra Di2 rear derailleur. The RD-6870 derailleur can handle a 36T cassette (w Wolftooth Roadlink), and the matching ST-6870 shifter (R) is more ergonomic than adding a XT rear shifter. Ultegra Di2 components are also easier to find on eBay than Di2 XT or Di2 XTR parts.
There's only one eTube wire from the front Junction A to the rear Junction B. If your frame and BB can handle internal routing, the TL-EW02 E tool can easily disconnect and re-connect the wire in the boom tube. The trick is to get the wire pass the front and rear BB shell (usually via slots or holes).
Good to know Ultegra RD can handle a 36T Cassette. I was thinking we would use Ultegra shifters regardless as I thought I read here they would shift XT and XTR. Moot I guess if the Ultegra RD will work and components being easier to find is important;-)
There's no room in the eccentric shell for wiring
AFAIK. How feasible is it to run the wiring using the guides for the existing RD cables? (apologies if the question shows a startling ignorance of how DI2 works and what is required to install it;-)