When the suction cup mount is attached properly it is very strong, I have gone some pretty good speeds with no problems! I also have used it on my helmet and though it looks a little weird, I dont even feel it up there! In the pic I posted (right side) the GoPro is in the same place as you see it in the left pic., I just turned it inward a little so it would pick up part of my bike too.
Note that I have the non wide angle version so yours will pick up more!
In this vid. clip the GoPro is the left screen, as you can see it holds up pretty well at just over 60mph (LOL), the suction cup mount is being used.
.... video by GEN1FALCON - Photobucket