Here is my latest bike tinkering little project. My Supernova E3 is the lefty mount version, which worked well for a handlebar hanger bracket. I recently considered the idea of a fork crown mount because I think lowering the light several inches gives a better beam on the road. The lefty mounting arm is not designed for fork crown mounting or any mounting with a hole that is in line with the light - the mounting arm is oriented perpendicular to the light. The even bigger issue is I have sidepull caliper brakes that occupy the hole to which most brackets would be attached.
My LBS suggested a B&M fork mounting bracket as a possible work around for the sidepull brake issue. The bracket is intended for use with Brompton folder bike. It is also designed to hold a light having a euro mounting tab, which the Supernova E3 lefty does not have (though there is a verision of the E3 light that is properly equipped). Despite these details , the bracket seemed adaptable and at $6 I thought I could afford experiment with it.
Miraculously, the light mounted without too much fuss after I found the right spacers. I'm happy to report that the bracket pairs solidly with the light. While the bracket is not intended for a light as substantial as the Supernova E3, the whole thing feels sturdy enough for me. At the theoretical risk of a cracking the bracket with the long term impact of low level vibrations, I am going to use it anyway.
There isn't a ton of extra room between the bracket and the headset crown race, but it's enough. The whole thing stays put without any disconcerting rattling or shaking. The on off switch is within reach. Most importantly, the light on the road from this new position is much better than the light available from a higher mounting position on the handlebars. There is a small wheel shadow right in front of the bike, but it hardly detracts from the performance of the light.
I am very happy with this setup, especially considering that it avoids the annoyance of mounting a front rack for the sole purpose of positioning a light. As you can see, the handlebars are also a bit less cluttered (please forgive the sloppy cabling), and the light is tucked neatly away ready when needed.