All very well if you have a handlebar. Personally I made an attachment to mount a light to the bolts on the seat handle Post Your Current Projects Here - #40 by aracer - which positions it to have the least leg shadow effect (there’s still some, but a lot less than with a light mounted on the seatpost and it’s not that irritating). Though that was last winter when I’d only been riding a few months and hadn’t yet learned to use the handle when riding - I think it will get in the way of using the handle (or at the least my hand will block the light), so I’m going to have to build something with a bit of downwards extension to get it out of the way.