For option A) and option C) Electrical Boxes, a generator tension cord is required. Option B) probably doesn't need one if the battery is going to be mounted on the swing-arm.
The idea is to put the least amount of tension as you can to still allow enough friction so the spindle doesn't slip on the tire.
A easy way to adjust the tension cord is have pedalee generate 25 watts more than the maximum you will be generating. Then decrease the tension until the spindle begins to slip, then tighten it until it just stops slipping.
