Prior to the Haibike FFS, I had already installed and run Schmidt SON28 dyno hubs on my Trek Soho DL and Specialized Fatboy. And long before those 2 bikes, I used to run a Classic Niterider with lead acid battery and a separate fixed/flashing rear battery powered tail light.
All for the idea that drives this thread; you never know when you are going to be caught out late at sundown & beyond for whatever reasons in and out of your control.
The added benefit of a Daytime running light, front and rear is that I really believe it helps alert oncoming drivers coming up on you to your presence.
The SON28 dyno hub is free juice. Nothing is taken from the main battery, it's all reserved for powering the motor. And as proven in this thread, you will never run out of power with a dynohub as long as the front wheel is spinning. Drag? Never has been an issue for me on all three bikes. Expensive, for sure. But anything worth putting on your bikes is always worth it in the short and long run.
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Mounted on the front rack, Schmidt Edelux II. Anodized aluminum housing, glass lens, not plastic.
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Those crazy Germans sure know how to design a reflector that focuses the light beam just like a modern HID lighted car, with a sharp cut off at the top. It also allows for tiny LED's to shine on that reflector and throw out 100 lux. Not a flame thrower like alot of other lights, but it does a nice job on the trail and roadways.
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Schmidt SON tail light. The front and rear lights provide light for about 5 minutes when stopped. Great for at lighted intersections or what have you. German traffic laws do not allow for a flashing red rear light as we see on most every US bike with a tail light. This is a fixed, bright red. I had a local bike shop relace the front rim to the new dyno hub, but I wired it up, putting the rear wire run to the tail light into the frame using the H-Bike entrance and exit pathways for the shift cable and rear brake hose. Dyno hub wiring and the specific terminals and connectors are smaller then what you will find at Autozone and they require care in crimping & applying shrink wrap, but it's very doable by any home bike mechanic.
Finally, that dyno hub has the capability to charge your cell phone or mp3 player or small battery cache, using the correct power control/voltage interfaces that are out there. I have the Busch & Muller E-Werk but have never had a chance to use it.