City bike, front light under rack: left side, right side or doesn't matter?
 

The title explains it - light is a B&M Cyo Premium.

If you are in US or “drive on the Right side of the Road” countries, then put the light on left side (NDS) of the bike. If you are in the UK, Japan, or “drive on the Left side of the Road” countries, put the light on the right side (drive train side) of the bike.

Technically, this is the ideal mounting method. In reality, mounting your light the width of your rack either way probably won't matter much. The important thing is to have a light.

If the light is low enough that the tire could cause a shadow on your right where the curb might be, that might be a consideration if you might want to see any curbing or edge of road on the right. In that case I would put it on the right. But if the light is high enough or forward enough that shadow from the tire is not a concern, I would use the left side for the reason noted by others.

You might want to pick a side and leave your wire somewhat loose and ride that way for a week, then decide and do your final wiring job then. The actual mounting of the light is easy to change, the wiring is where it can get complicated depending how hard you try to hide your wiring.

My light is up high enough that traffic from either side can see the light, but I do have some shadow on the left side from my tire, if you are curious there is more on my light system here:
https://www.bikeforums.net/electroni...b-charger.html

I've read one recommendation to put the light on the outside (right in the U.S.); the stated reasoning was to illuminate the fog line.

For my part, I don't trust the pavement where I ride enough to ride 1/8" inside the fog line. I do, though, want my light to be visible to oncoming traffic, most of which I worry about turning left in front of me. So I'll keep mine on the left so the tire doesn't block forward visibility of the light, and if I can't see to the right for three feet in front of my wheel, well, I'll ride far enough to the left so that won't matter.

I would put the light on the side closer to oncoming traffic. Putting on the opposite side from oncoming traffic could cause the light to be obscured from oncoming road users by the wheel. If the light is fully above the wheel then I don't think it matters to much.

I´ll try it on the left side for now - thanks all!

Do you have/use front panniers? If so, a center mount might be preferable.

Some B&M lights are not well sealed on the bottom or back side, keep that in mind when you install it to minimize tire spray in wet weather.