I would rather mount it on the handlebar so that it could be adjusted up and down. I have the same flashlight and use a cheap (but very effective) two fish u lock mount. (It's 2 for $12 vs 1 for $8 when you buy the flashlight specific model) https://www.amazon.com/Two-Fish-Lockblocks-U-Lock-Mount/dp/B001P9EWKE
where can you find those velcro straps for the Lock? I've been looking everywhere for a way to strap my Fahgettaboudit lock to the bike frame instead of in my pannier bags! Is it by chance these?
https://www.amazon.com/Two-Fish-Lockblocks-U-Lock-Mount/dp/B001P9EWKE
I end up using these attachments (designed for a bike lock, but work for flashlights fairly well) with my lights when biking.
In the bicycle world we like to promote buying local and buying from bicycle brands.
https://www.twofish.biz/bike.html
So here is the Twofish Unlimited Lockblock (same as the twofish unlimited flashlight holder)
https://www.amazon.com/TwoFish-1-Lockblocks-U-Lock-Mount/dp/B001P9EWKE
Based in Berkley, CA
I got these off of Amazon. They work pretty well.
Two Fish Lockblocks U-Lock Mount https://www.amazon.com/dp/B001P9EWKE/ref=cm_sw_r_cp_api_iUcBxb0P45DV9