Ashaman42 said:
By notchy do you mean that at low speeds the light doesn't stay on constant (ie flickers) or that you can feel a notchiness through the wheel?
And is a very low speed 1mph, or 3mph or...?
Sorry Ashaman, what I meant was that if you hold the wheel in your hand and spin it, you can feel it resist where the magnets are. You can (sort of) feel this when you're going real slow, but its only in the very last milliseconds before the stop, or if you're trundling backwards / pushing the bike without weight on it.
I use a SON20 on a 24" wheel, and can't keep the 'bent upright at speeds below full brightness. I'd estimate 3mph for full power to the cyo. It does flicker for the first second when you pull away from a standstill, but this is only between the standlight (half bright) and main beam (full). Strobe is just on the edge of detection really, and only visible if you're close tailing a silver car.