03-01-2018 02:53 AM - edited 03-01-2018 02:54 AM
How strong does the attachment need to be, will there be much vibration, and how much room do you have for the mount?
The Pro Handlebar / Seatpost / Pole Mount will only fit a pipe 9mm or greater. The Jaws: Flex Clamp will securely hold 0.6 to 5cm (you can remove the Flex Goosneck and just use the Clamp). There are also Clip Mounts that you can find on Amazon. They have a pretty good grip but for such a small diameter pipe you'll probably have to hang it from the clip.
Other than that, I think you will just have to DIY a custom clamp.