I have a Go-Pro that I use on the bike, I have mine set at 720 and 30 GPs, 1080p gets you very large files sizes. I tried my camera on the top of my bucket (helmet) but found at the faster speeds it tended to drag my head back, causing severe neck ache forcing head forwards all the time. The Go-Pro has a big front profile and catches the wind a lot, I tried it on the right hand side of my helmet but found that my helmet blocked some of the kerbside view and again it caught the wind and caused a lot of buffering and wind noise.
I now have a sturdy handlebar clamp and shot video through the screen of the bike, I also purchased a skeleton housing that allows better sound recording and the camera is protected from wind, rain and stone chip behind the screen. Another option is a chest harness that you wear, good for mountain biking and running as well.