Originally Posted by
echappist
Di2 soldering question:
my road bike is internally routed, but not Di2. i'm thinking of splicing two cut cables and solder them back. The trick here, of course, is that the soldering has to occur while one part of the cable is within the frame.
if anyone have experience doing this, i'd like to hear more. I'd presume that one needs to clamp the frame to a bike stand and have a workstation setup nearby to do the actual soldering. In terms of ease, is it better to do the soldering closer to the rear derailleur or closer to the bottom bracket? I'd guess the latter would be preferable since the soldered portion can get tucked into the frame?
if you're talking e-tube and your bike handles internal routing, i'm not sure you'd have to do any soldering.
i've soldered 7970 wires before; it's trivial. did we go through this dialogue a few years back? the individual wires are really fine. it's not hard and you can even do it as a first project--but you probably should practice a bit on something else. at the time i wanted to extend some wires and there were NO long 7970 wires available; cat V wiring is a good alternative, and replaceable.
watch a couple youtube videos on soldering if you are unfamiliar. i'd highly recommend heat-shrinking each of the 4 internal wires AND putting heat shrink over all that as you are essentially breaking the weather seal. the problem with this is that unless you've drilled out your internal guides, you'll have a hard time stuffing that back into the frame, unless you've been very creative.
if you do it right you will never have to access the soldered joint(s) again, so where you put it should be immaterial. ideally you allow for extra slack so you have room to work and then just have that stuffed into the frame, but if the guides are entry-to-exit, you can't do that.
if your bike is set up for internal mechanical, you need to think about how you will handle an internal battery.
really long e-tube wires are available, and with the smaller connectors on the end (5mm diameter...the same as brake cable outer housing) there's a really good chance you should not need to cut anything open.