Originally Posted by
CEBEP
Found _this_test [URL removed so I may quote ...] comparing SON, SP and Shimano dyno hubs. Does it correspond to SP hub model used in R&M Birdy 3?
SP hub seems to be least efficient with highest drag.
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 ...