There is no such thing as a free lunch for sure but I can't see the drag on a bike from one of these being detectable by anything other than lab equipment. A 5 watt rated LED bulb lights up my entire kitchen to a decent brightness so a couple of LEDs flashing every now and then isn't going to take much power at all. They are being marketed as safety DRLs so they don't have to produce large pools of light for showing the way at night and when you consider the thumping great output of the electric motors in our case it won't be noticeable at all.
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Dunno. My wife has a modern hybrid commuter with a shimano hub dynamo. You can actually perceive the drag when you switch the light on.
Maybe a brief pulse every now and then from this new system would work, however I'm still a bit skeptical. I nearly always use flashing lights when commuting in the daytime, but I think the lights I like best are around 80 lumens - and this is only achievable in flash mode. Anything dimmer is heading towards unsatisfactory (for me anyway), and somehow, I just can't see something like this product being able to provide anywhere near enough power for 80 lumens or so. In fact, I'm wondering if it would even be an order of magnitude from it, maybe even two!
And as for using it on ebikes, well....even more of a case as to why all should have a power outlet for driving lights directly from the main battery!
Its almost as bad as the question always asked "does the battery charge when you peddle"
