Gear Combo Guru
Join Date: May 2007
Bikes: Spec' Tarmac (road), Ridley Fenix (commuter & fast tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder)
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Electronic shifting wires for coupled tandem - extra-long wires or couplers?
We're considering using Ultegra Di2 shifting on our Co-Motion Speedster Co-pilot. I've done some tests to be sure that the gear combinations that we might want to run should work OK with Ultegra Di2 derailleurs, so now I'm just trying to determine what wiring we will need for a tandem.
We'll obviously have to run the wiring externally, and we will need a coupler in the wire that we can disconnect, preferably somewhere on the captain's down-tube. We could just unplug the wire from the front junction box, but that would not be as convenient as something that is located lower down. Shimano only lists wires up to about 1 metre long, so how do people do this on a tandem, which needs about 1.5 metres between the front and rear junction boxes? Are there extra-long tandem wires available, or is there a coupler available that can be used to daisy chain two wires together - that would obviously be the ideal solution for us.
I've seen a few photos from NAHBS and other places showing coupled tandems with internally routed wiring and couplers in the wires, but where would I obtain such parts after-market? I haven't seen anything like that offered for sale or in Shimano's tech docs.