Originally Posted by
wphamilton
There will always be drag, starting with the power output to the light and increased by the inefficiencies. Dynamo hubs can have 3 to 9 watts worth roughly speaking, which can be noticeable (moreso at lower speeds). I suspect that there is less drag with this technology than for dynamos with equivalent power outputs.
There will always be drag, but will it always be perceptible? Hub dynamos and bottles have cogging as the poles interact with the permanent magnets. This causes noticeable vibration that is mistaken for drag but really doesn't add to drag, since it is an energy storage effect. The Magnic (I assume) has no vibration, so the drag should feel smooth, like very gentle braking.
I don't really see why the efficiency in this system will be a lot better, if at all, than that of a recent SON or SP. Slowing down the rider is slowing down the rider, whether or not the rider can perceive it. If into the bargain it puts out half the light or half the illumination (this group still hasn't grasped which of these performance metrics is actually important), then it is not a step forward despite the novel technology. Not even when version 2 brings its functional spec close to the level where Germany could consider certifying it. The performance target is still to match a SON/Edelux 2, SON/Luxos, or a SON with one of the other top-level B&M lights. If we want to argue about price/performance, just substitute the Shutter Precision PV-8 for the SON, at $130 each versus $200+ each, with a Lyt or other mid price but high-end B&M. I still think "efficiency" is a case that must be proven: Lumens per mechanical watt or illuminance per mechanical watt.