In regards to "The Paperboys" comments about what camera to buy, I'd suggest the below -
Essentially as previously stated you're looking for a Camera that's "3CCD", which allows the camera to view Red, Green and Blue separately.
WTF does that mean though? Basically better and sharper picture quality.
You also want to look for something with the highest pixels, like you would with a stardard digital picture camera! Again, more pixels, better picture quality.
There's debate now about MiniDv (tape) and Hard drive/DVD camera's. personally I used MiniDv but destroyed a camera due to dust/weather and have converted to Hard Drive. personally I think less moving parts = less wear plus you don't lose quality/suffer breakups in conversion from tape to computer
Also worth considering is does the camera have the ability to connect and external mic as the internal ones are crap and subject to wind distortion. It may not mean that much in biking action shots as most movies have soundtracks, but think about things such as interviews with riders and that all important thudding and breaking noises after a crash!
Lastly, take into account things like start up time, as there's nothing more annoying than filming a race and missing a rider whilst waiting for your camera to go from standby to ready! Plus Battery time, as think about how long a race/ride takes. Most camera's only run about 60 minutes so can you get bigger/cheap extra batteries.
My background is amateur rally (car) videography. I've filmed/edited/produced and sold a video of my local states rally series.
On a parting note, for everyone (me included) that has dreams of running out and making their own DVD I say go for it. But don't be fooled into thinking you can film one session of your mates, edit it with something you down loaded over the net and have something like what you can buy.
It's doable but it takes 100's of hours of footage and patience!
Best way to learn it get out there and start shooting, get hours and hours of footage and play it back. You'll quickly learn about camera angle's, focus, framing etc and you're on your way.
For everyone else, there's youtube