I am going to have a go with this unit. All that is needed is a decent fast 2Gig chip and its good for 2hours of high res video. Plus it's waterproof. You get a helmet mount and also a bike mount but it is so light that you could velcro it or strap it to the fairing or ram scoop vents etc.
You can get them for about £80.00 if you hunt around. And that is cheap enough to experiment with without stuffing your precious £500 camcorder.
http://www.oregonscientific.co.uk/pr...raincamera.htm
Here is a site which is selling them at a good price but do a search around for better
http://www.aceselectronics.co.uk/pro...od=487&xSec=55
Also this site has some good stuff on action cams
http://www.3-cam.com/