E-bike motor kits typically come with (at least) a motor control unit and a hub motor and a front or back wheel. (You use your existing tire.) The motor has three power-wires (3-phase) and 5 more sensor wires. These need to be connected to the motor contol unit, along with the throttle cable and power connection. The cables on my first kit were only long enough to install the motor control unit in a bag attached to the back of the seat. With the battery in the front, and the throttle and brake cutoff lines on the handle-bars, there were wires running everywhere.
So yesterday, I finally got around to splicing an extension on the motor wires (shown), and shortening the throttle signal cable (so I could use the cut-off segment to extend the motor signal wires) – 22 solder connections total, with lots of heat-shrink tubing.
Now, the motor in the back has a single cable that runs all the way to the handle-bars, where it plugs into the motor control unit that’s in a bag with the battery, hanging from the handle-bars. It’s much simpler and better balanced, and it’s now easy to disconnect the three cables and (temporarily) remove the bag from the bike, to charge it or just ride it without the extra 20+ pounds.