thanks a lot. I took the head of a mini tripod and bolted it to my helmet, after that I used hot glue to give it the everlasting touch. After that I took my Canon Power Shot A 470 and mounted it to the head, that's it.
It took a while to find the right position, I recorded such a nice track at fairly high speed but the camera was in the wrong angle. After that I had to delete it, but then I got water in the carb and the damn XR wouldn't speed up enough. It's all about finding the right level.