Taking the time to talk again a little bit about the cheap little things one can find over ebay. Got this gizmo for 5$ with free shipping from China all the way to Europe.
It states to be a clamp for bike handlebar mounting of a photo digital camera but I'd think more at something like a lightweight GoPro, ContourROAM or these type of action camers. Anyway, my real interest for this thing was as a studio clamp for holding flashes or other accessories.
The jaws are padded with rubber for extra grip and can open wide enough to clamp even on my Giottos MT8350 center column. You have a screw with which you set your opening and then a lever that grips the jaws on the support. Once fixed into position you now have 2 axes of control for your "payload". One is for tilting done with a screw while the other is for rotation through a rather ingenious spring loaded teethed coupling between the actual clamp and the mounting plate. The spring is quite strong and great for impressive static loads but can't deal with any bumps and vibrations given by any bike riding on anything but ideal tracks. The mounting plate has a metal screw with a nut that helps to further lock the payload. The nut is also doubled with a rubber washer for extra grip.
As I've said, I've done some testing on my Giottos MT8350 as a support and a Canon 580EX II as a payload. It's doable without much effort even horizontally with the flash extended but it's obvious the mounting plate junction is under excessive effort for it's capability.
In the end, it's 5$ that weren't spent for nothing, I have a clamp that works if taken to appropriate use but it must not be mistaken with the whole different world of metal clamps like the ones from Manfrotto or even the way cheaper CoolLCD's Super Clamps.