Originally Posted by
fatbikeGM
Good find!
On the R&M site it only says "Hub dynamo Shutter Precision" so no idea but I would not expect ours to be better.
The way I read the graph in the cylclingabout article under "Results: Dynamo Hub Drag and Output Power Using Different Lights" ist that until 20 km/h is reached the SP has the least drag. That would be fine by me.
I am surprised by the total amount of drag though: Nearly 9 Watts (and half of that even with the light off) at 25 km/h is quite a lot. My average performance over an hour is about 250 Watts so that's 3,6 %. Cyclists have gone to great lengths to pursue smaller gains in efficiency.
Between this, the weight of my luggage and the excess weight on my hips atm I wonder how fast I could be without all that ...
Yes, interesting! I would expect ours to be
different because this seems to be a big wheel test and SP offers different dynamos for small wheels, optimised for higher rotation speeds. So
different, but not necessarily
better. Anyway, for the Birdy it is a moot point since the SP is
afaik the only disk brake dynamo hub that will fit the Birdy, because of the custom disk spacing it uses.
However I have another small wheel bike, and there the SON is an interesting option, because of the very low drag with lights off (which is most of the time). Their folding specific hub won't fit as it is 74 mm and has no space for disks, but they claim the SONdelux is "for road bikes and smaller rims" so it's optimised for high rotation speeds.
I would also like to see a test of the Shimano 1.5W hubs. They are small, lightweight and deliver half the power, but with higher rotation speeds of small wheels it might be enough. They would be a bad option for USB charging, though.