Have you considered a dynamo lighting kit? There cheap and modern sets are much better than the old vintage ones from years ago. Drag is equivalent to a dry chain or the difference between slick pavement tires and off road tires on pavement. In other words after about 10 minutes you forget the drag is even there. With the dynamo locked in the off position there is no drag at all. The only downside are the type of bulbs used in them. Cheap sets come with bulbs made like flashlight bulbs. There bright but only last a few hours. Lights with halogen bulbs last a hundred or so hours and consequently cost considerably more. New dynamo LED lights last about 50,000 hours and will most likely still be functioning long after your not! They also cost considerably more unless you DIY your own. I've been running a dynamo lighting system for a couple of years now. Never needing to worry about batteries gives you a great sense of freedom!