Kingfish said:
Luke, I haven’t removed magnets from the hub periphery so I cannot confirm or deny the presence of a flux ring (back-iron).
On the black E-Bikekit 9C front hub that I have, the spoke flange and ring is indeed steel. Magnets stick to it so well that I just left one stuck on the flange to use for the CA speed sensor, and even at 34MPH no-load off-ground it doesn't budge, nor has it moved with all the road bumps and stuff, either.
But on the silver one from Icecube57 is aluminum, and a magnet won't stick to it at all, although I can feel the pull from the internal magnets and flux ring pretty strongly.
Both of them do have a separate flux ring within the spoke flange, presumably bonded to each other in some way, or interference-fit.
Regarding the triggering of lights, I have found that *some* of the sensors are sensitive enough to be affected by me sticking a couple of harddisk magnets on the lowest points of the frame (bottom of front forks and kickstand base) on my alloy-framed DayGlo Avenger. So far, neither the Fusin nor the 9C will change the light triggering behavior at these lights, but the magnets do, on a very few lights.
On the much bigger steel-framed CrazyBike2, which will occasionally trigger some of those same lights itself, the 9C does make some of them trigger more consistently. But again, the magnets (placed on the fork) make some difference at other lights that didn't trigger before.
The thing that makes the most difference is the speed and position at which I approach and cross the first threshold of the sensor; if I manage around 1/2 of the speed limit for that road and I stay on the centerline of the sensor, then I will usually trigger more lights than any other method I've tried.
FWIW, I have less trouble triggering them than several motorcycles I've seen, some of which cannot trigger them at all, apparently. Kinda P/Od one guy, when the light went green as I rode up in the lane next to him, when he'd been sitting there at least a couple of minutes (I could see him the whole time I was approaching, a mile or more away).