Fly6 is designed to attach to the seat post only. There are a number of reasons however the most important of them is stability of footage. There is a unique but simple fixing method that ensures Fly6 sits tight against the seat post allowing the camera to deliver surprisingly smooth & steady footage.
Our research and tests show Fly6 will fit effectively on 95% of bikes no matter what style of seat post (circular, square and 'aero'). We can't cater for situations where the user sits low against the frame however a good bike fit should provide for enough space for Fly6 (some examples: http://on.fb.me/1eN7deU).
Attaching Fly6 to the back of jerseys, backpacks or saddle bags will result in very unstable and probably unusable footage defeating the point of having Fly6 there in the first place. Some people have asked about attaching it to their helmet - we don't believe this will capture incidents that occur behind you very well and have not designed Fly6 to be there!