Magnic Microlights & Wega work without contact, but not without energy consumption. With less than 1 watt per lamp/generator, however, the effort is extremely low, so that even at high speeds there are hardly any losses worth mentioning. As a rule of thumb, you can add about 1-2 seconds of additional effort per lamp over 10km.

Magnic Microlights and Wega lamps have already been used for some time trials/bike races and larger night tours: