The fit-and-forget nature of these lights is their real bonus – magnets on the spokes generate the electric current, so there are no batteries to change and you’re never without visibility.
Fitting is very simple, and because there’s no actual contact anywhere, there’s no resistance. On the downside, the SL500 model is a ﬂashing unit only, and it stops when you stop (at a junction, for example). A better option would be the SL520, which stores enough energy to keep the light ﬂashing for a few minutes.
The rear light mounting bracket is seatpost-only, but step up the range to the SL620 and a rack-mounted version is available – and that’s the one we’d go for.