Stable contemporary, but really usable ...

... Probably only for the motorcyclist.
For mountain bikers (and other cyclists) this indeed very stable support is rather partial functionality.
Shocks such as mountain biking inevitable, and even small bumps in the road, that is on asphalt, be passed without mercy to the camera (Rollei S50), that is not nearly a "quiet" film image comes. The permanent shocks are passed undiminished to the microphone. The Tonergebnis is through the direct connection of the tripod holder to the bicycle frame (with me Alu, Carbon is worth a try) completely absurd (by comparison, they put their ears on the table and knocking and scratching at the table). Videos must therefore be "accompanied" with other audio signals such as music; should turn its own "movies" or the thing "Action Camera Films" has as hobby.

Well, for my review of this holder is not responsible, the one will probably have cheaper -whether or teurer- with any other holder. But compared with my helmet shots where surges through the human body can be smoothly absorbed shots with fixed mounts on mountain bike (handlebar) are not qualitatively comparable. Only the angle of view, from the perspective of a link / frame, the helmet camera might be preferable because it is sitting on the helmet by construction of the Top Mount uncommonly high (and also one can look like one of the Teletubbies).
But here criticism: despite the better image positioning on the bike itself, the rigid primary gaze has the handlebar (oa fixings on the bike) the individual perspective of a helmet attachment, beaten by panning and targeted head rotations, for my taste. At the helm all seems more dynamic and flexible and just much quieter, sliding.

Ultimately, I have therefore promised more action from this feeling / a handlebar mount.
The filmed and shot images are but hardly worth by constantly ongoing shocks.
So that part is probably only for motorized bikers the road choice.

But back to the holder itself:
The wing nut on the ball joint, with Cross Trail and downhill is not exactly brilliant. Only through the power of the fingers, although ergonomically shaped wing nut is not tightened firmly enough. One has a tool the wing nut 'ne half turn or fix more solid, so that the camera does not turn. The mother would have to be larger so that more leverage auswirkbar.
Also, I have a piece of leather around the underlaid the Bügelklemmung, for better / firmer fixation and (sound) absorb the shocks.

All in all an expensive -zwar but- an extremely stable power pins; which in turn is more than disturbing the Gewichtspuritaner of mountain biking.

Conclusion: Wiedermal no egg-laying Vollmilchsau and just only really useful for motorcycle (since but may possibly the diameter of the clamp is too small).