Functional bikes. Not Porn not Anti

I guess what I should really have asked is does the drag/friction increase when the lights are in as opposed to off.

I suspect the drag is always there so becomes less noticeable and you're as well leaving lights on all the time.

Update: Cycled to work on my other bike this morning and I think I noticed it being a lot free-er wheeling. I say "think" because I did have this thread in mind so it could have been psychosomatic but I think it was a least a bit less draggy.