I've got a Sony HDR-AS200VB action cam that i've used a few times to record my bike rides. However, it's not ideally suited to helmet mounting as it's shaped like a mini camcorder so I've only ever used it mounted on my handlebar.

I could do with a helmet-mounted camera that isn't too 'in your face' - like the GoPro style cameras that are mounted on top of the helmet are.

Ideally I'd want a cylindrical-shaped camera that can be mounted to side of the helmet. The only ones I've seen that might fit the bill are Contour Roam cameras but I don't know whether these can be mounted to the side of the helmet.