Mounting a 12v motorcycle light on bike seat rails? So now that I built a 12 volt (more like 11v) battery for my bike I would like to accessorize it with some 12v lights to get a unique look. I'm looking at motorcycle tail lights, but they all have two parallel bolts coming out the back 82mm apart. The rails on a bike seat seem to be about 50mm apart. Is there something I get at the hardware store to jerry-rig a solution? ![Source: Back of the bike seat: (two horizontal rails 50mm apart with an angle at the end). Maybe I could zip tie in a ubolt pipe clamp somehow? ![enter image description here](

I would just use a standard electrical mounting 4" crossbar:

![electrical box mounting 4" crossbar](

You can run the wire through the hole in the middle, and the slots on either side should accommodate both the posts from the light and whatever you use to attach it to the rails. (P clips, as Criggie suggested in a comment, would be the simplest approach for that.)

(You can buy them individually, but if you're like me you have a bin full of random electrical crap with a good dozen of them...)