Really Super Long Derailleur Cable (each)cad1long
1.1mm x 3100 galvanized shift cable, Jagwire brand
If your bike is a tandem or something like 57cm or bigger and you got (or are gonna put) high and wide handlebars with bar end shifters, you may need a longer than the usual 2 meter derailleur cable to reach all the way backbackbackback to the rear derailleur. If you don't know if you need a cable this length or not, mock up your build with the proper length shifter housing in place and run a string from the shifter, along the shifter housing, down the downtube, under the bb, along the chainstay, the length of the little rear der housing piece and then to the rear derailleur cable pinch bolt and measure how much string it all took. It's a very rare build to exceed this cables 3.1 meters (~ 122").