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Join Date: Nov 2008
Location: Reno, NV
Bikes: Civia Hyland Rohloff, Swobo Dixon, Colnago, Univega
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Originally Posted by peliot
It seems to me that the standard 6W power output of the dynamo hubs I've seen is overkill for an LED light (not a super bright, just a "be seen" light). Are there any dynamo hubs out there specifically for LED lights that operate at lower power?
I imagine it would be cheaper and less resistance than the 6W ones, hence the question.
Nominal output of most dynamo hubs, and tire driven sidewall dynamos, is actually specified as 3 watts rather than 6. At higher speed they can put out more than 3w which allows them to handle some fairly powerful lights. SRAM also shows 2.4 watt hub dynamos too.
Originally output was intended to handle a 2.4 watt headlight incandescent bulb front lights and a .6w taillight bulb which were basically little more than "to be seen" safety lights. Such halogen bulb lights are still available.
Bright dynamo driven LED headlights are a quite recent phenomenon and only started appearing 4 to 5 years ago. I suspect that dynamo hub manufacturers have not chosen to decrease power output for two reasons. The most important is that in the European market minimum dynamo output is a government regulated requirement, at least in Germany. The second is that there would not be appreciable cost savings involved in manufacturing lower power hub dynamos.
If you want battery free "to be seen" bike lights take a look at the Reelight products. They work off of magnets attached to the wheel spokes.
Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
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