Originally Posted by
wphamilton
Because a bottle generator will have bearing friction, the magnets or coil spinning on an axis. It will also have some loss in the rolling surface interfacing with the tire. In this kickstarter generator it's the magnetic eddies that are moving, the flux lines cutting across fixed coils, so there is no mechanical friction. When I visualize this, all of the drag is directly related to the power generated, so I expect it to be more efficient in that sense than bottle generators. A hub generator, maybe not much difference but depending on the engineering.
We already know that the drag is greater than the ultimate power consumed by the light and we've got some pretty good data, here and there, on drag from various dynamos so that side doesn't really need any proving. The actual drag from this tech, yes I agree that we need some measurements to put the question to rest. That may be a little tricky for DIY tests though, since a coast-down doesn't get precise enough for that small amount of rolling drag and simply spinning the wheel unloaded doesn't actually translate to the drag on a loaded wheel. So we may have to wait for someone with more sophisticated equipment and a little time on their hands.
While bottle generators are another thing entirely, and have lots of drag due to friction, hub dynamos may or may not perform better than the Magnic. I don't really know myself yet. I don't have any capability to perform the measurements either. I will have both a Magnic light and a dynamo light available to me in April so I'll at least be able to do a test of perceived drag, if I can feel either.
As for weather sealing, the Magnic is completely sealed as there are no external moving parts or switches. Whether it is entirely waterproofed down to 50 feet is something else.
I have Canti's on my bike and it worked using their simple bracket that attaches to the brake pad holder. I think the bigger problem is disk brakes as there is nothing at the rim.
I agree that the position of the iight is a bit awkward. I mounted my taillight on the right side as you ride on the left on NYC's one-way streets. It is the accepted practice here even if it isn't a universal one. Buses are on the right. If you were close enough behind me on my left you may not see it, but by then its already too late!