totally agree with barondla....
The gest biking photo gear is exactly that, an Optio W (series) P&s, plus a mini gorillapod. With any other non waterproof p&s, you'll still have to care when muddy, rainy, dusty, wet, etc... conditions, that make all the fun in mountain biking, and are not compatible with 99.9% of any camera gear.
Look at my setup. It's no nonsense, no worries, always ready.
Attachment 14289
You will be so pleased with this handy and worry free setup, plus it takes almost no space. In my case, I just wrap the gorillapod to bike's frame, and take camera in shirt pocket.
RB