alt Hacker NewsThere are also dynamo powered LED lights which only provide light while riding the bike, and about a minute afterwards (I assume from an internal capacitor). They are not detachable but why would that be necessary? From what I can tell they also don't require regular replacement.
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A reliable dynamo hub setup can be very cool for the right situation, but the up front investment to rebuild your wheel around a dynamo hub is expensive. The power output is also on the low side compared to the light output you can get from the battery units.
Not having to charge anything or worry about batteries running out in the dark is a real benefit.
It's all on the very opposite end of the cost spectrum than the cheap bike light in this post though
These are fine for bike commuters, and I’ve had them before. But they are in general not fine for recreational bicyclists; these people would gladly pay a hundred dollars for a new tire to shave off three watts and are not about to add any unnecessary human-powered accessories.
After 15 years of dynamo hub, I’m about to switch to a power bank connected to usb light. Dynamo hubs are quite fragile and not easily maintained. Cheap front hubs are found everywhere and they less drag. I have a few Deore hubs that I found on the street on abandoned bicycles.