I guess that most people mount the light head to the seat post with the supplied mount and then mount the battery to the frame.
I'm having problems for a few reasons, though, one being that I don't have much seatpost showing, maybe 4.5" which is enough to mount the light head or the lithium ion battery (in a saddle bag) to my seatpost, but not both. So I tried putting the battery in the saddle bag and mounting the light head to the tops of my chain stays. It would've been fine on an aluminum or steel bike but my bike is all carbon and the rubber band that mounts the light head actually left indentations in my seat stays! I knew that carbon doesn't tolerate clamping forces but I didn't think the rubber band concentrated that much pressure. Now I know
I would mount the battery to the top tube but my rear brake cable is mounted in the 7 o'clock position, occupying the space where the battery would be. That and my bike's black-tinted clear coat seems easily scratched so I would like to not mount anything on the frame.
Again, my bike is carbon so I don't have braze on's, a rack or anywhere to mount the light head or battery off the frame.
I guess I'll either have to get a frame bag or a bento box for the battery, though I really didn't want stuff bouncing around when I hop or jump a pavement defect.
Mounting this light is such a hassle that I'm starting to not want to even use it and I wonder if I even need a 140 lumen tail light at all. I don't do that much night riding along expressways or highways with 50mph traffic, which was where I originally assumed it would be beneficial. I've been using a Mars 3.0 since last summer with few close calls.
Do I even need this damn thing? Is it worth the hassle? Any thoughts are welcome.